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Technical Faqs

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01 General Building

  1. Can Acraseal be used to seal sandstone and composite concrete tiles

    22nd February 2011

    Acraseal can be used to seal any porous stone or cement based tiles. We would always recommend trialling in a small inconspicuous area first to ensure compatability and that the deisred finish is attained. Once applied to a surface, Acraseal is very difficult to remove.

  2. Can Larsen Latex Self Leveling Compound be used as a floor covering between a ground bearing slab and suspended slab with a step of 25mm between each.

    14th October 2014

    Larsen Latex Levelling Compound can only be used up to depths of 6mm and so would not be suitable in this application. However, SLC1550 Fiberflex is a fibre reinforced self-leveller and is suitbale for use up to 50mm depth and should be suitable in this application.

    Neither Latex Levelling Compound or SLC1550 are suitable as a final wearing finish. If a final wearing finish is required SLC2000 Industrial should be used.

  3. Can you advise, after using Larsen Concentrated Algicide if the surface can be painted?

    10th September 2008

    After the Larsen Concentrated Algicide has been applied and has dried, the surface can then have subsequent coatings applied, i.e. paint, plaster, render etc. It is important to ensure the surface is sound, clean and free from other contamination before applying subsequent coatings.

  4. Can you recomend a water repellant for a old stone built house that has been plastered on the outside. We would like something that we could apply by brush to the plaster.

    2nd July 2014

    We have several products which could be used all of which must be applied to bare (not painted) render. Suitbale products include Water Repel, Repel N and Repel 38.

  5. Could i have sone information relating to health and safety for the use of mortar plastiser.

    2nd June 2009

    The Health and Safety information is provided in the safety datasheet on the product page - Mortar Plasticiser

  6. Couldyou recommend a waterproofing product suitable to use on an existing terrazzo floor for a new vinyl to be laid on.

    16th February 2010

    By waterproofing product I would assume you mean a damp proof membrane.

    If the moisture content of the existing terrazzo floor is too high to apply the vinyl directly, then Larsen DPM can be applied to the terrazzo. The floor should be mechanically prepared (e.g. enclosed shot blasting) to give a clean, lightly textured finsih free from contamination. Then apply Larsen DPM in two coats (constrasting colours are available for refernence).

    Depending on the adhesive used to stick the vinyl, a minimum of 3mm of levelling compound may be required (consult adhesive manufacturer for advice). If this is the case the wet second coat of DPM should be fully broadcast with a dry single size sand e.g 16/30 at a rate of 2kg per sq. m. when cured, excess sand should be removed to provide an adequate mechanical key for the levelling compound.

  7. Do you have a product that can be added to a plaster mix to help prevent cracks in smooth "rubbed up" render finish?

    22nd November 2008

    Generally, cracking in plaster is the result of shrinkage and there a few main causes and methods to reduce incidence of cracking.

    Cause: Shrinkage in blockwork. All masonry substrates are prone to shrinkage as they dry out if plastering is applied beofre the structure has 'settled' there is a greater risk of cracks developing at the corners of windows and doorways.

    Solution: Allow blockwork to dry out sufficieintly before plastering. Include suitable reinforcing (scrim cloth etc) at critical areas.

    Cause: Render is too strong.

    Solution: As a general rule of thumb, work on the principle hard centre, soft shell. As you work out from the wall subsequent coats should get weaker to reduce the risk of cracking. The stronger the mix the greater the risk of cracking.

    Cause: Normal drying shrinkage. Sunny or windy conditions especially can cause the render to dry out too quickly resulting in crazing of the surface.

    Solution: Try to work in the best weather conditions and allow adequate curing by covering with polythene etc or misting with water over the first 7 days.

    Additional measures can be taken to reduce the incidence of cracks in render e.g. by adding polypropylene fibres to mix or a polymer additive. However, the best solution is to employ the best working practice where possible.

  8. Do you have any epoxy resin with shear strength more than 20MPa?thanks

    7th July 2009

    Larsen Epoxy Bond has a slant/shear strength of >30MPa.

  9. Do you still have repel 38 or what other waterproofer product for outside brick & plaster surfaces to seal them

    27th July 2015

    Yes we still carry this product but have recently rebranded it as Stain Repel.

    Also in the range is Storm Repel (previously Repel N) which is a creamy one-coat water repellent whihc is deep penetrating and easier to apply on vertical surfaces by brush or roller.

  10. Hi, Does your Latex Levelling Compound 20kg come with an emissions mark such as the GEV-EMICODE® EC1PLUS that is marked on setcrete product sold by wickes.

    1st November 2016

    Our Latex Levelling Compound is not currently tested to the GEV-Emicode classification system

  11. How do I clean cement off brick (DARK RED) coloured pavers.

    20th May 2009

    Remove as much of the cement or mortar residue as possible by mechanical means (scraping or brushing). Wet the area fully, then apply Brick and Patio Cleaner as directed.

    As Brick and Patio Cleaner is an acid based cleaner great care should be taken in its application, also it is worth noting that it will attack all cement based materials so an inconspicuous trial area should always carried out first.

     

  12. I am laying granite 600 by 600 paving slab with 10 mm gap in the garden.is it OK to use stain resistant wide joint grout for external use.

    5th June 2014

    Yes, Stain Resitant Wide Joint Grout is suitable for external use. Alternatively, if these are thicker slabs we also manufacture Streetscape GPM which is a gunnable pointing mortar.

  13. i have a white slapdashed
    wall about 12 years old and a red colour has appeared. is there anything made to clean it?

    7th March 2011

    The red colour is probably as the result of an algae growth. Larsen Concetrated Algicide will be suitable to treat and clean the wall. The following is the product datasheet.

  14. I have concrete pavers which have previously been improperly sealed, leaving the dark pavers streaked and milky in color. What can I use to strip down these pavers to remove the old sealent and to restore them to their natural color?

    23rd February 2010

    This is dependent on the nature of sealer used, however a proprietary paint stripper would be worth trying.

  15. I have put sandstone on part of my house, however it seems to be letting water in. Do ye have a suitable sealer to stop this.

    4th November 2009

    Larsen Water Repel can be applied to most absorbent surfaces such brick, render or in this case sandstone and will provide a water repellent seal against driving rain.

    Water Repel must be applied to a dry surface in dry conditions.

    An alternative is Larpruf SWR which is a water based silicone type water repellent.

  16. i need a adhesive fo fix some brick slips to the exterior of my house, i beleve i used some larsen quick dry floor tile adhesive a few months ago and on the packet am sure it said i could use it for brick slips,if i am wrong what can you recomend thanks

    19th February 2010

    Our cement based tile adhesives are suitable for use externally and would be ideal for fixing brick slips. It is probably better to use a Flexible (S1) standard setting product e.g. Larsen Professional Flexible Standard Set. This will give a long working time and allow adjustment of the brick slips.

  17. I need to bond stainless steel plate 180sq (3mm thick) to concrete (precast unit). Which product do you recommend?

    29th April 2008

    We have a number of bonding agents which would be suitable. For light duty, non-structural bonding, then I would recommend Fast Grab Construction Adhesive or Bond & Seal. For heavy duty, structural bonding, I would recommend Larfix E.

  18. I need to know the rate at which I should dilute Acraseal. Have you got a system to dilute and what equiptment is advised to spray this product on. Should I put Algicide or Acraseal on first on concrete tiles and slate?

    30th June 2008

    Acraseal is supplied ready for use and should not be further diluted.

    Acraseal should be applied by roller, brush or suitable sprayer e.g. Larsen Galvanised Spray Unit. When spraying care should be taken to avoid the overspray contaminating surrounding areas as the selaer will be very difficult to remove. Acraseal is solvent based - ensure adequate ventilation exists and read safety datasheet before use.

    Where there is a build up of algae etc, apply Larsen Concentrated Algicide before sealing. Allow treated area to fully dry before applying any sealer. Where there is a very heavy build up of dirt, moss etc. it is often advisable to clean with a powerhose, then apply Algicide, allow to fully dry then seal as required.

  19. I want to use a Larsen Easy Foam as feeler to my roof wooden construction between placed the joists and Roof Insulation Board. \r\nI want to now something about Larsen Easy Foam structure.\r\nIs Larsen Easy foam has closed or opened cell structure?

    8th December 2014

    Larsen Easy Foam is closed cell when cured.

  20. I wanted to ask if Larfix E could be used to bond galvanised lateral restraint straps to precast units/blockwork rather than using bolts/anchors? The lateral restraints were not placed at the time of building and I am trying to fit them remedially, but do not want to use bolts/anchors.

    23rd September 2011

    Larfix E will bond the straps very stongly to the surface of concrete or blockwork, however I would recommend running it past an engineer for advice.

    Depending on what you are bonding to, will have an influence as you will be relying on the surface strength of the substrate to carry the load (pull-off or shear) rather than an anchor (pull-out).

  21. Is it ok to use Bitumen Paint internally on brickwork (intend covering with plaster when paint dry)

    10th January 2011

    The use of Black Bitumen Paint in this application will provide a surface which would be very difficult to apply plaster to.

    A better product to use would be Larsen Rubberproof which is a water based, rubberised, bitumen emulsion. This should be applied in two coats with the top coat fully broadcast with a clean dry 0.6-1.2mm sand to provide a key for the plaster.

     

  22. Is Larsen brick and patio cleaner harmful to plants?

    16th June 2008

    Larsen Brick and Patio Cleaner is a Hydrochloric Acid based cleaning product. While it is not classified as 'Corrosive' it would be expected to damage acid sensitive surfaces and this could include plants. It is also possible that spillages on soil would upset the pH of the soil temporarily in the localised area and this too could be damaging to plants.

  23. Is there a way I can treat old red bricks on my gable wall to prevent them from crumbling further?

    27th March 2015

    Unfortunatley we do not have any products which would repair crumbling bricks. However, crumbling bricks are usually a result of freeze thaw damage as a result of water ingress. Treating the bricks with a water repellent like Larsen Storm Repel will prevent further water ingress, while still allowing the bricks to dry out, this should reduce further damage as a result of freeze thaw.

  24. seeking advice on how to prevent cracking in a narrow band of external render applied to metal lath fixed to timber beam, dimensions 0.3m deep by 3.5m long? i'm thinking expansion joints, glass fibre mesh and polymer additive.

    20th October 2010

    Your idea is correct, add Larcem 25 SBRBond to the render mix (dilute 3:1 with clean water and use this as the gauging liquid). The inclusion of reinforcing mesh and a separation joint will further reduce the risk of cracking.

02 Concrete

  1. 1.the best way to apply your dustproofer?\r\n2.how long dustproofer takes to dry?

    13th August 2015

    Dustproofer can be applied by brush, spray or watering can. It is important to wash off any product remaining on the surface after the final coat has soaked in and usually within 2 hours. Dustproofer will typically dry within 4-6 hours and can be trafficked after 24 hours.

  2. Can patio and brick cleaner be used internally. I have a large area of limestone walls that have a build up of motar. Thank you.

    12th June 2014

    Brick and ptio cleaner can be used indoors with great care, but it is generally not recommended as the acidic fumes may corrode exposed metal. Further, acid based cleaners are generally not suitable for use on limestone or other carboniferous stone as they will attack and etch the stone

  3. Can you advise on the suitability of using Larsen Quickset in a high moisture area on a ships deck. We have concerns about the flexibility of the product in that it will not provide sufficient flexibility as the repair thickness on the ship is approximately 50mm thick and will be placed down on top of steel deck plates. Can you confirm whether this product has an IMO certification?

    19th December 2013

    Firstly Quickset does not have IMO certification.

    Secondly, Quickset is not a 'flexible' product but does have a high flexural strength of approx 9MPa, so is much stronger in flexure than a screed or concrete.

    If you require any further information, phone our office on 02890774000 and ask for Technical Sales.

  4. Concrete has popped in back yard can you advise me on what material there is available to lay a screed over the top and what material i would need to use to bond this to the exixiting concrete. many thanks

    17th April 2011

    It is important to adequately prepare the surface by water jetting or other mechanical means to ensure a solid substrate free of all loose or weak material. Once this is achieved, Larsen Professional SLC2050 External self-levelling compound can be applied to the surface without the need for primer.

  5. Do you have a surface sealer and curing membrane product for application to green concrete?

    21st October 2015

    Larsen Acrylic Concrete Sealer (previously Acraseal) is suitable for this application. 

  6. Hi could you recommend a super plasticiser for making wet cast paving \'copping stones

    22nd October 2014

    Chemcrete 100Plus is a very good all round superplasticiser and would be a good starting point

  7. Hi I am looking a polished concrete sealer that will leave a high sheen on the surface when dried its for worktops etc.

    29th January 2017

    With polished concrete it is often best to achieve the sheen/gloss through polishing alone. A gloss sealer will often wear and mark more quickly than the concrete. 

    Successive polishing up to 3000 grit will usually be sufficient to achieve a high gloss finish. This can be protected with an impregnating sealer such as Larsen Stain Repel which offers protection against oil and water based staining. Best results are achieved by applying before final polish or simply buffing the surface once sealer has dried. Stain Repel will not affect the appearance of the finished surface.

    A wax based polish can be used on the finished surface to improve gloss but it must be borne in mind that this will require maintenance throughout use and reapplication, probably every year.

    Personally I think the application of Stain Repel to protect the finished concrete is sufficient. As this will allow the concrete to build up its natural patina with use but still protect it from more severe staining.

  8. Hi there,- in the tech datasheet for larcem 25 SBR it is recomended that chemcrete 100+ be used as a super plasticiser when producing microconcrete. would there be any problem using chemecrete HP3 super plasticiser in its place?

    12th January 2012

    Chemcrete HP3 superpalsticiser is also suitable. Make sure the superplasticiser and the SBR are added separately to the mix.

  9. Hi, I am looking to purchase a product to slow down the curing process of concrete, usually 35 or 30 Newton. I am a concrete printing contractor and need extra time to colour and stamp the concrete. I would like an admixture which can be added to the lorry on site. Please can you advise on such a product that will not effect the final strength of the concrete.

    26th October 2014

    Normally the concrete producer will add admixtures to the concrete at plant. Any additions added on site pass the responsibilty of the concrete to the contractor.

    That said we have a suitable admixture whihc can be added to the lorry or at plant - Chemcrete R610. Retardation of the concrete is dosage sensitive, i.e. the more R610 added, the greater the retardation and trials should be carried out to establish the required dosage.

  10. Hi,rnWe are using a concrete mixture to cement a nichrome element into a refractory clay block. We are looking for a hydrophobic additive that is able to with stand temperatures op to 220 degrees C

    9th April 2014

    Unfortunately we do not sell anything which woudl be suitable. Most of our water repellent additives are based on fatty acid soaps with melting points around 150C.

  11. I am building a house in france this summer using ICF for all the walls and beam and block flors .we are making all the concrete ourselves but would like to know if you advise using a super plasticizer in the mix especially for the walls. if so which one?

    26th March 2012

    It would be usual for a project of this size to pruchase the concrete form the local ready mix supplier to ensure quality and consistency. However, with care sizeable projects can be achieved with site mixing. Chemcrete 100Plus at around 0.4-0.5% of the cement content, i.e.0.4L per 100kg cement.

  12. I am installing a 1700sq/ft freezer room that operates at a temperature of -25 oc (minus 25). I employed a contractor to power float the floor to give it a sealed finish, however the floor hardened too quickly. Apart from taking out the floor again (150mm fibre mesh, 40 newton concrete) is there a product available that will seal the floor, operate within a temp. of -25 and will withstand the combined weight of a forklift and pallet travelling on the floor on a regular basis. (combined weight is 2,500kg)??

    17th March 2008

    Larsen Impregnation is a high quality, 2-pack epoxy sealer for concrete. It is ideal for use in industrial situations to seal and protect the floor. Impregnation will be suitable for a service temperarure -30 to +60oC.

  13. I am producing glass fibre reinforced concrete products the basic ingredients are 1 to 1 white cement and limestone aggregate with some scc and polymer admixtures,\r\nBut the supplier of the cement has recently changed the source of the raw materials \r\nAnd I am no longer able to turn out the product in 12 to 14 hr as before ,it now takes from 20 to 24 hr have you a product that will allow me to speed up the setting time to allow me to reach the previous de moulding time of 12 to 14 hrs

    21st May 2014

    We have a number of accelerators for use in concrete or mortar mixes and should work equally well with white portland cements. Chemcrete CF200 is a chloride free accelerator and Frostproofer and Rapid Hardener is a Calcium Chloride based accelerator. Both products will reduce setting times and increase the early strength.

    For your specific mix it will probably take a bit of trial and error to find the optimum dosage.

  14. I am renovating an old red brick house that has some structural cracks. What grout do I use to repair the cracks with?
    Also an old I beam is rusting. What product can I apply to retard the rust?
    Thanks

    29th April 2009

    Structural cracks in a house should be fully investigated by a professional surveyor prior to carrying out any repairs. Depending on the cause, nature and size of cracks there a number of options as to which product/method to employ. At the simplest, the repair required may be only aesthetic and the most severe the wall may require 'stitching' or the wall needing underpinned. Until this is known a product cannot be recommended.

    Depending on the location of the I beam the simplest option may be to blast or wire brush back to bare metal and then painting the beam with something like Black Bitumen Paint.

  15. I have a wood block wooden floor in the kitchen which is lifting away from the concrete underneath due to damp. I want to remove this wooden floor and then apply Larcote DPM to seal the floor. Can a self leveling screed then be used on the resin so that a lino floor covering can be laid? If so which products would you recommend?

    27th October 2011

    Yes. The best method is to apply the DPM in two coats. The second coat is then fully broadcast while still wet with 0.6-1.2mm dry sand to excess (apporx. 2kg per sq. m.) This is then allowed to harden and the excess sand removed by brush or vacuum to leave a sandpaper-like finish which provides a mechanical key for subsequent coatings, i.e. levelling compounds.

    The levelling compound to use depends on the thickness to be made up - up to 6mm use Larsen Latex Levelling compound; up to 25mm use Larsen SLC1500.

  16. I have an issue within a church building. The issue is with the windows. the mullions are concrete and go from outside to in with no cavity. this is causing dampness on the inside walls. I am trying to find some sort of insulation to apply to the wall which can be allowed to have plaster then applied on top of it. At the very least we need an appropriate paint.

    4th November 2011

    There are two issues to be dealt with separately in this case. Firstly the prevention of damp soaking through the mullion - this can be prevented by applying a suitable water repellent impregnation treatment. I would recommend our product REPEL C for this application, which is a creamy silane water repellent which when applied to the external face of the mullion will leave it with a very low water absorption.

    Secondly, the cold bridge created by the mullion can be treated with careful detailing of a suitable insulation material and probably plasterboard to the internal face of the mullion.

    I would not recommend just applying a paint or insulation to the inside as the damp will still be travelling through the concrete and will likely surface elsewhere as a different problem. The application of REPEL C should stop the ingress of moisture through the concrete.

  17. I have concrete imprint on my driveway.The paint has lifted/flaked in areas and
    I want to re paint it.The colour is black.Where in Ashbourne,Co.Meath ,Ireland are the stockists of Larsen's paint/sealer?

    12th July 2010

    Normally, printed concrete driveways are not painted, rather the concrete is coloured and then the surface is sealed with a product such as Larseal Super or Larsen Acraseal. We do not sell coloured paints or coloured sealers for this application. For details of where Larseal Super or Acraseal can be purchased contact our Dublin Office on 018348255

  18. I HAVE INSTALLED A LARGE BIOMASS BURNER WHICH BURNS 500 KG BALES OF CARDBOARD,THE PROBLEM IS TOO MUCH ASH ACCUMULATES IN THE BOTTOM OF THE BURNING CHAMBER . I WANT TO MAKE OR BUY A SLOTTED CONCRETE SLAB 1.5M X 1.5M X 0.15M(DEEP) CAPABLE OF WITHSTANDING TEMPERATURES OF 1400 C

    18th May 2015

    Unfortunately we do not make any suitable products. I am not sure how available the cast slab would be, but there are castable refractory products on the market which could be cast into a mould. 

    For example - kilnlinings.co.uk appear to sell this sort of product.

     

  19. I recently applied Acraseal to a newly poured concrete driveway (5 days old). I did this based on the contractor's recommendations. Should I have any concerns regarding the concrete curing properly, sealer working etc.

    20th October 2010

    Acraseal can function as both a sealer and a curing membrane for fresh concrete. Ususally when used as a curing membrane it is applied as soon as the concrete can be walked on. There should be no problems with your application, however in order to achieve a good seal you may want to apply a second coat of Acraseal.

  20. I wish to seal new exposed aggregate concrete in a driveway. The sealant should be non glossy and tough and re-touchable. Please advise on best option

    17th September 2013

    Depending on the finish required we have a few options.

    Repel 38 - will not really change the appearance compared to untreated. This is an impregnating water and oil repellent which greatly reduces dirt pick-up or staining.

    Acraseal - is a solvent based hard wearing acrylic sealer. To some degree gloss and sheen can be controlled by the number of coats - the more coats the greater the film of sealer and the greater the gloss.

    For further information contact Jonathon Monney - 07710864634

  21. Is there any compatibility issues in using HP3 super plasticiser along with your SRA or the SC1? Is there there any compatibility issues with using all three together?

    22nd August 2011

    There should be no issue using these products together in a mix. While there shouldn't be any issue, it would be advisable to dose separately to the mix. Always carry out trial mixes before use.

  22. The builders had just left my house after laying a 25m2 concrete screed \r\nthen the dog escaped we now have a patio which is a mess . Covered in holes paw prints scrapes etc these range from 25mm deep prints to 3mm scratches. I would like a outside product that I could floot across the patio that would fill the holes and make everything in my world ok again\r\nmy biggest problem is the patio runs away towards a drain \r\nmany thanks\r\nSterling groves

    23rd September 2015

    There are a few of options.

    We have a patch repair product called Rapid Patch which could be used to skim over the paw prints etc. While this is close in colour to concrete the repairs may still be visible.

    Another option is SLC2500 which is a external levelling compound. With care this could be mixed slightly stiff to allow for the falls.

    Finally, a thin section (10-15mm) polymer modified screed could be applied incorporating Larsen SBR Bond. This would be trowel applied like a traditional semi-dry screed.

    If you would like to discuss further contact our Technical Sales on 07710864631. 

  23. We are currently designing some precast concrete elements. We are seeking an \"adhesive\" that will create a bond to shot blasted steelwork i.e. we want concrete to adhere to structural steelwork.\r\nDo Larsen offer such a product?

    7th December 2016

    We have Larsen Epoxy Bond, which is a 2 part epoxy bonding agent. When mixed it is painted onto existing concrete, steel etc before placing new concrete. New concrete muct be placed within 20 minutes of painting Epoxy Bond

  24. We are looking for a product to seal a painted concrete surface which would then allow us to lay ceramic tiles.

    23rd January 2011

    When tiling onto painted surrfaces it is very important to ensure the quality and bond of the paint is sufficient to support the tiling installation. Good quality gloss or epoxy paints may provide a suitable base for tiling, but cheaper floor paints and emulsion should generally be mechanically removed before tiling.

    If the paint is sound, I would recommend using Larprime EU. This is a two pack solvent free epoxy primer. After mixing apply to the floor with a roller and then while still wet apply a broadcast sand scatter of dry 16/30 sand at a rate of 2kg per sq. m. Leave overnight for the primer to harden and then brush or vacuum to remove excess sand. This will leave a sandpaper like finish to provide a mechanical key for tiling.

  25. We are looking for product that will allow render to be applied to fair face concrete precast panels. Can you assist.

    15th January 2009

    Larcem 55 is a styrene acrylic copoloymer emulsion bonding agent which is ideal for use in just such an application.

    Ensure the wall is clean and free from mould oil residue (power washing may be required) or other contamination. Mix Larcem 55 neat with cement until a slurry consistency is reached (normally about 3:1). This is then applied to the wall and either:

    1. Apply render wet on wet to the Larcem 55 slurry (within about 20min of appliying slurry).

    2. Apply slurry to wall and finish with a brush or textured roller to a stippled finish and allow to harden before rendering (this will provide a mechanical key).

  26. We concreted our back yard about 2 years ago this spring/summer. Recently the concrete has started to pop up in places, probably due to rainwater trapped, forming molecules, and now with the heavy frost these have started to open up all over the yard area. Is there anything that can be applied to combat this problem. I would be grateful for your advices. Many thanks

    6th February 2009

    You are probably correct in your assumption. The action of water trapped in the concrete surface freezing causes an increase of the volume of the water as it turns to ice and this can cuase pop outs. There are also other causes for example the presence of pyrites in the aggregate.

    The best way to prevent the pop outs resulting from frost damage is to include an air entrainment admixture (e.g. Chemcrete E110) in the concrete when it is mixed. This creates a controlled air void which provides space for the ice to expand into without causing damage.

    As this concrete is in place the only option would be to seal the surface with a suitable product to prevent moisture soaking into the top layer of the concrete and hence reduce the risk of pore ice formation. However, as this is external concrete and therefore unlikely to have a damp course beneath, there is still the risk of ground moisture migrating up through the concrete and in turn this could freeze during a a bad frost.

  27. We own a building where much of the internal concrete supports are exposed. Can you recommend the best quality Matt sealant for the concrete, one which is long lasting. The building is over 50 years old.

    4th December 2015

    We have a couple of solutions. As a sealer we have a solvent based Acrylic Concrete Sealer. While this is not matt, single coat application tends to soak in to the concrete leaving a low sheen. Site trials would be required to ensure the required aesthetic can be achieved.

    Alternatively we have Stain Repel which is a water, oil and stain repellent impregnating sealer which leaves the surface of the concrete almost unchanged.

  28. we want to use standard floor screed mix of sharp sand and cement with fibres for garage screed but understand that we should take added measure for strength and surface wear. whats recommended.

    25th March 2014

    Adding Larsen SBR Bond to the mix will improve the abrasion resistance of the screed. Alternatively applying a sealer or paint coating may be sufficient in a domestice garage.

  29. What product do I seal concrete with to allow me to tile after 3 days curing

    7th April 2010

    Current recommendations and best practice suggest concrete should be 6 weeks old before tiling. This allows the concrete to have gained a suitable level of strength and dryness and ensures that the majority of any early age shrinkage and associated cracking has taken place before tiling.

    The main risk from tiling too early is that drying shrinkage cracking may occur in the concrete leading to cracking or debonding in the tiling installation.

    If you are forced to tile onto concrete this early we would recommend using a decoupling matting system, such as our Seri-Dec. These systems help prevent stresses from the substrate being transmitted into the floor finish.

    For further information consult our new tiling brochure or phone for further technical advice.

  30. What superplasticizers will you advise ready mix concrete suppliers for long distance deliveries (180 minutes) under 33-36 degree celcius climate temperature

    27th December 2014

    I would recommend carrying out trials before attempting this using two admixtures - Chemcrete R610 (set retarder) and Chemcrete 100Plus (Superplasticer). Once suitable dosages are determined, a single component blend could be supplied for this job.

  31. What would you recommend for a concrete cast in situ garage roof! It would be good to remove a depressed (puddle) are to prevent pooling at the same time. Thanks.

    10th February 2014

    The easiest option would be to use a self-levelling compound to level the surface.

    If the levelling compound will be exposed to the elements, the product to use would be SLC2500 which is suitable for external use.

    If it will be protected from the elements and dampness then SLC1550 would be suitable.

  32. When applying a second coat of larsen concrete dustproofer to concrete floor, how long do you leave the first coat before applying the second?

    21st April 2009

    The second coat can be applied as soon as the first has absorbed into the concrete.

    After the application of the final coat has been applied, it is important to ensure there are no puddles of Dustproofer remaining on the surafce. Before teh final application has dried, the floor should be well rinsed with clean water.

03 Flooring

  1. 1.the best way to apply your dustproofer?\r\n2.how long dustproofer takes to dry?

    13th August 2015

    Dustproofer can be applied by brush, spray or watering can. It is important to wash off any product remaining on the surface after the final coat has soaked in and usually within 2 hours. Dustproofer will typically dry within 4-6 hours and can be trafficked after 24 hours.

  2. can any of your self levelling products be used externally ie to level the floor of a large dog pen?

    21st December 2009

    Unfortunately we do not have an external grade self-levelling compound at this stage.

  3. Can dye be added to Larsen slc 1500? Can I use concrete dye? Would like to add brown, black, maybe terracotta red. And what would be the best finish for that floor?

    28th July 2017

    Small amounts of pigment could be added to the product, however as SLC1500 is quite dark in colour it may prove difficult to produce anything other than shades of grey. However, you would need to carry out your own trials to ensure suitablility.

    I woudl also recommend using SLC2000 as SLC1500 does not provide a wearing finish.

     

  4. Can i use your professional slc 1550 flex over decorative epoxy floor covering? Or floor require preparation with specialiat primer?

    18th March 2015

    Normally we would recommend removing existing paint coatings by mechanical means (shot blasting or grinding). However, if the coating is definitely epoxy and is frimly bonded, then carry out the following preparation.

    1. Sand surface of existing coating.

    2. Vacuum.

    3. Apply one coat of Larpime EU (Universal Epoxy primer) and broadcast 0.6-1.2mm sand into the wet primer at a rate of apporx 2kg per sqm.

    4. Allow primer to cure (preferably overnight)

    5. Remove excess sand and ensure primed surface has a sandpaper finish with no bald spots. Apply SLC1550 as normal

  5. Can latex screed be laid on top of vinyl tiles containing asbestos (old Marley style tiles) before carpeting?

    22nd December 2016

    Latex Levelling Compound has not been tested as an encapsulation method of dealing with asbestos. If there is a risk of asbestos release from this flooring it is recommended to take specialist advice.

    In terms of the product adhering to vinyl tiles, there is normally no issue when the tiles are clean and free from dirt, polish etc. The bond can be further improved by priming the tiles with Larsen Primer Grip 360.

  6. Can you advise on a suitable product to provide a DPM to a floor where there is a break in the existing DPM and moist is rising into the property?

    11th June 2015

    Larsen DPM is a solvent free 2part epoxy coating which should be applied in two coats where a functioning DPM is not present. 

    Depending on the application the second coat should be sand scattered to give a mechanical key for subsequent levelling compounds or tile adhesive.

  7. Could you please recommend a product for raising a screed floor by 8-10mm. The screed has Underfloor heating and will be tiled.

    13th June 2008

    Larsen Professional SLC 1500 would be the best product to use. This is a single pack (water mix) self-levelling compound for application from 0-25mm depth. It is suitable for use over underfloor heating.

    For further information and datasheet, follow this link - SLC 1500

  8. Could you recommend a surface finish to apply to a new power floated concrete screed floor. The use is for a shop store area with foot traffic, trolleys and cages being moved about.

    17th September 2013

    We have a number of surface sealers which can be applied to concrete floors to reduce staining and help improve abrasion resistance. The best is a two part epoxy product - Larseal Impregnation

    If the concrete has not yet been placed, another option would be to use a dry shake surface hardener - Larsen Shaketop

    For further information, contant Jonathan Mooney 07710864634

  9. Couldyou recommend a waterproofing product suitable to use on an existing terrazzo floor for a new vinyl to be laid on.

    16th February 2010

    By waterproofing product I would assume you mean a damp proof membrane.

    If the moisture content of the existing terrazzo floor is too high to apply the vinyl directly, then Larsen DPM can be applied to the terrazzo. The floor should be mechanically prepared (e.g. enclosed shot blasting) to give a clean, lightly textured finsih free from contamination. Then apply Larsen DPM in two coats (constrasting colours are available for refernence).

    Depending on the adhesive used to stick the vinyl, a minimum of 3mm of levelling compound may be required (consult adhesive manufacturer for advice). If this is the case the wet second coat of DPM should be fully broadcast with a dry single size sand e.g 16/30 at a rate of 2kg per sq. m. when cured, excess sand should be removed to provide an adequate mechanical key for the levelling compound.

  10. do we need to use a special latex screed on top of a floor treated with the speedo accelerator

    29th September 2009

    No. Once hardened, Speedo screed can be treated as any other, so any common levelling compound may be used.

  11. Do you do a non- cementitious latex levelling compound?

    3rd June 2011

    No not currently. However if your application is to level a gypsum based screed, then a standard latex levelling compound could be used providing the screed is first sealed with two coats of suitable primer.

  12. Do you have a product to seal granite paving?

    5th July 2010

    We have a number of products which are suitable for sealing ganite paving, depending on the finish required. If you are happy for the appearance of the paving to remain relatively unchanged , iwould recommend the application of Larsen Streetscape Protector applied in two coats.

  13. Garage Floor repair:
    the top surface of the garage floor is breaking down and generally the floor is very dusty. What products should we use to repair and seal the floor?

    10th September 2009

    Remove as much loose material as possible and then treat the floor with either Larsen Injection Resin or Larsen Impregnation - both are low viscosity epoxy products which should penetrate the concrete and help to bind up and strengthen any loose or weak material

  14. Hello,\r\nDo you sell to the general public or is it trade only?\r\nI want to purchase your epoxy dpm to lay over old vinyl tiles which were laid in the 1970\'s.Is your product suitable for this and can I lay laminate flooring directly on top of it?\r\nThanks

    23rd March 2017

    We wouldn't recommend our DPM to be applied directly onto vinyl tiles.

    If you are laying laminate unbonded, then you may be able to use a 500gauge polythene sheet and then a laminate underlay board.

  15. Hi I am a contractor and I am currenty pricing a renovation job in a very old building complete with red stone tiled floor. I am wondering if any of your flooring products be suitable to use it level the floor. There are holes in sone of the stone aroud 20mm deep so I will need a product with workin depth of around 30mm the room is roughly 13ft x 13ft. Any advice and prices would be most helpful

    7th April 2014

    Larsen SLC1550Flex would be suitable for levelling this floor. Before starting work I would advise taking further advice. Old buildings were typically built without a damp course, but the older construction methods were such that ground moisture was free to evaporate and the buildings were much more breathable. Sealing the floor or the building can create problems with condensation or damp.

  16. Hi I am considering using your quick drying cement after an oil spill in my home to fill in my livingroom floor, my only concern would be that I have a foil covered kitchen beside this and was told this can damage the foil when drying? could this be a possibility?

    14th August 2012

    Our Dry4 Binder can be used to make a fast drying screed. However, even with fast drying screeds there is a lot of moisture present over a whole floor area. As this moisture dries out of the screed it will raise the relative humidity in the room. It is concievable that this moisture could affect some timber substrates if they are free to absorb moisture, however the issue will be the same no matter what sort of flooring is installed.

    You should probably talk to the supplier of your kitchen units and perhaps consider renting a dehumidifier to remove moisture from the air.

  17. Hi \r\nCould you please advise me on the most suitable self levelling compound to just cover 3mm under floor heating cables that are laid on a 12mm ply floor which is covering 18mm floor boards. This is then going to be covered with a porcelain tile so I require a compatible tile adhesive too.\r\n Thanks

    18th June 2014

    SLC1550 would be suitable, applying a minimum of 6mm (10mm would be preferred). The floor must be suitably prepared and free from excessive movement. The tiles can then be laid using any flexible tile adhesive.

  18. Hi, I am interested in your stain resistant flexible grout. I am about to lay mosaic floor tiles, each tile is 100mmx50mm and they are set in a brick pattern on web backing on a 300mm x 300mm sheet. As they are a rustic design, the gaps between the tiles varies from around 2mm and 7mm, with 4-5mm being the average. Hence do I use the narrow joint or wide joint grout? Will the wide joint grout be able to cope with the small gaps or will the narrow joint grout be able to cope with the wider ones?

    30th March 2010

    Our Stain Resistant Wide Joint Grout would be the most suitable for this application as it is suitable for use in joints of 2 -20mm. Regading colour samples etc if you call our Sales Manager Martin Colbey (07710864636), he should be able to locate your nearest stockist.

  19. hi,i got a lot of lardec woodstain and primer on the side of a mobile home,cladding sides,and is there a produck I can get to remove it? I have already tried thinners and turpentine,regards derek

    21st July 2017

    Unfrotunately there is no easy answer. Lardec is a solvent based alkyd woodstain, so generally I woudl expect paint stripper to remove staining form most surfaces, however this will be much more difficult on abosrbent surfaces where the pigments will have penetrated.

  20. I am tiling a bathroom floor.\r\nI have an 18mm marine plywood floor. I have attached underfloor heating to the surface with the primer supplied and to allow the adhesive tape to stick. I have 600 x 600 porcelain tiles. I have the following LARSENS materials. Pink acrylic primer. SLC 1550 and Wooden floor fast set.\r\nI am confused as to how to use the primer.\r\n1. Do I use it neat or 1:1 on the plywood before the SLC 1550 and do I apply one or two coats?\r\n2. After I have applied the SLC and allowed it to dry. Do I use the acrylic primer again before using the wooden floor rapid set tile adhesive? If so how do I apply this?\r\n3. I take it applying Wooden floor rapid set to SLC 1550 is ok?\r\nI obviously need a flat surface and to skim the UFH before applying the tiles.\r\n4. Also as the adhesive is very rapid from what I have read, is it ok to mix enough for a few tiles at a time then once these are straight mix some more etc? It also states about how you need to twist the tile. Theres not going to be much twisting with a 2-3mm grout line!

    10th June 2012

    Firstly it is important to ensure the plywood has been screwfixed and is stable and will be free form deflection and also to ensure the undertile heating system is suitable for use on a plywood substrate.

    \r\n

    Then mix and apply the SLC1550 over the heating elements, again check the heating supplier\'s recommendations, but usually a few mm over the wires is sufficient to protect them from the tiling trowel.

    \r\n

    Allow the levelling compund to harden (usually overnight is sufficient) and apply one coat of the Acrylic primer pre-diluted 1:1 with water.

    \r\n

    The tiles should be fitted with a solid bed of adhesive ensuring as close to 100% coverage as possible between adheisve and tile. For best results use a thick bed solid bed trowel and back butter the tiels with a thin skim of adhesive.Do not use dots and dabs. A minimum of 3mm grout joint is recommended.

    \r\n

    I would also recommend, as there is undertile heating, leaving a larger perimeter joint where the tiles meet the wall etc and fill it with a silicone sealant or similar.

    \r\n

    It is ok to mix part bags of adhesive just keep the water ratio the same, approx 2.5L water per 1/2 bag of adhesive (10kg).

  21. I bought some of your Larsen slc 2000 self levelling a while ago. It is now 6 months out of date.\r\nWhat will happen if I try to use it?

    18th February 2014

    The shelf life for most of our cement based products is 6 months in good storage conditions. We could not guarantee the performance of products outside this.

    The likely effects will be dependent on stoarge conditions but the product will likely be lumpy, very slow to set and may not gain anywhere near full strength.

  22. I have a black limestone patio that needs sealing. Is your impregnating sealer suitable for use outside?

    6th July 2015

    Yes our Impregnating sealer is suitable for external use. As with all applications of Impregnating Sealer it is important to ensure sealer is not left to dry on the surface. This is best achieved by allowing the sealer to soak into the tile for approx. 15 minutes and then wiping any excess off the surface with a clean lint free cloth.

  23. i have a customer whos tiles have lifted off the floor. after inspecting the floor it seems that she has put a layer of varnish on the finished floor to keep dust down which proably lead to the tiles lifting. she now wants to retile the floor. is there anything i can put over the varnish or would i be better to remove the varnish. would flexibilzing the floor and throuwing sand on it letting it set and brushing off the excess ans then laytexing the floor be ok before tileing it again or not. please advise

    12th March 2010

    The best method would be to mechanically prepare the floor e.g. grinding back to a good quality absorbent substrate. It is worth noting that the floor may be of poor quality if it was initially 'varnished' to keep the dust down. An alternative option would be to use a decoupling membrane such Larsen Ser-Dec and leave the'varnish' in-situ.

  24. I have a large kitchen floor total area30 sq. m which has been badly pock marked by the elements as the house was being constructed. Would it practical to use your self levelling compound to provide a flat surface. Half of the floor area will be carpeted and the other half tiled. Would it be necessary to cover the whole floor or would I get away with just filling the craters.

    26th April 2012

    The best reult would be to remove any loose or dusting material (if necessary grinding the surface) before applying a suitable levelling compound over the entire floor. If the \'pock marks\' are particularly deep, fill these the day before levelling the floor.

    SLC1500 or SLC1550 would probably be the best products to use.

  25. I have a wood block wooden floor in the kitchen which is lifting away from the concrete underneath due to damp. I want to remove this wooden floor and then apply Larcote DPM to seal the floor. Can a self leveling screed then be used on the resin so that a lino floor covering can be laid? If so which products would you recommend?

    27th October 2011

    Yes. The best method is to apply the DPM in two coats. The second coat is then fully broadcast while still wet with 0.6-1.2mm dry sand to excess (apporx. 2kg per sq. m.) This is then allowed to harden and the excess sand removed by brush or vacuum to leave a sandpaper-like finish which provides a mechanical key for subsequent coatings, i.e. levelling compounds.

    The levelling compound to use depends on the thickness to be made up - up to 6mm use Larsen Latex Levelling compound; up to 25mm use Larsen SLC1500.

  26. I have an old stone cottage with an old suspended wood floor in one room. I want to reduce the draft by putting vinyl down over the wood. I was advised to roll a layer of bitumen first to seal the floor as much possible. Is this safe/effective in terms of moisture collecting under the vinyl? Are there any problems (or other alternatives) I should consider?

    19th July 2011

    Ideally the best solution would be to access the under side of the floor and install suitable insulation - there are various metods by which this can be achieved.

    Draughts can be greatly reduced by sealing joints between floorboards (larger joints with timber slivers or cork) and below skirting with Multipurose silicone or Painter's Caulk.

    The most important thing to ensure when either sealing, covering or installing is that the timbers remain sufficiently ventilated to prevent moisture build-up and ensuing rot.

  27. I have had to take up an Amtico floor as it failed after 2 months. It was layed on top of ceramic tiles. The installers did not initially damp test the floor before putting it down. The ceramic tiles have now been removed and we have tried to remove the ceramic tile adhesive underneath but some of it won't budge. Using a kango machine is doing too much damage to the floor scredd underneath. The floor is now quite uneven and bumpy. On top of that there seems to be a problem with the damp proof membrane under the floor slab and we have high moisture readings and this is what contributed to the floor failing initially. How can the floor be damp proofed now, how can it be levelled and prepared for a new flooring and what is the best flooring solution in your opinion? Can Amtico be laid on it again? Do I have to go back to ceramic tiles? It is a kitchen.

    16th July 2010

    A surface applied damp proof membrane can then be applied to the floor to deal with the damp problem - Larsen DPM. It is best to apply DPM to a flat surface therefore the residue of adhesive can either be removed with the use of a floor grinder (rather than a Kango) or, as long as the majority of adhesive has been removed from the floor and any remaining adhesive is firmly bonded, a leveling compound can be laid over the floor. If this <6mm, I would recommend the use of our Latex Leveling compound.

    Depending on which adhesive is being used to bond the Amtico, a second application of leveling compound (min 3mm) maybe required over the DPM to provide an adsorbent base for the glue.

     

     

  28. I have just had anhydride screeded floor tiled with larsen flexible rapid set adhesive (screed sanded & primed with larsen acrylic primer). My query is how long should I leave the adhesive to cure before turning the (Wet)underfloor heating system back on. I understand that it should be turned on at low temp initially and ramp up gradually.

    11th February 2016

    With anhydrite or other calcium sulphate screeds it is imperative that moisture testing has been carried out and the screed is below 0.5% before tiling and that the underlfoor heating has been fully commisions as per BS EN 1264. 

    Typically we would then recommend that the tiling is left for 7days before heating is turned on and the temp intially increased by 5C per day.

  29. I have timber floor varnish that has a square foot of woodworm do I use a paint stripper to remove the varnish and then apply the preservative

    8th November 2016

    Woodworm Killer must penetrate into the timber to be effective and as such paints or varnishes should first be removed.

    Depending on the age of the timber and nature of the discovery of the woodworm, treatment may not be necessary. Woodworm typically burrow and eat through timber for 3-5 years before emerging from flight holes as the adult beetle. It is common for these old burrows to be exposed when old timbers are sanded prior to varnishing. It is therefore worth investigating for evidence of a live infestation, for example the presence of beetles, worms, and fresh dust at the exit holes.

    If the infestation is live, it is recommended to treat the surrounding areas and underlying joists etc and not just the immediate area of concern

  30. i need a adhesive fo fix some brick slips to the exterior of my house, i beleve i used some larsen quick dry floor tile adhesive a few months ago and on the packet am sure it said i could use it for brick slips,if i am wrong what can you recomend thanks

    19th February 2010

    Our cement based tile adhesives are suitable for use externally and would be ideal for fixing brick slips. It is probably better to use a Flexible (S1) standard setting product e.g. Larsen Professional Flexible Standard Set. This will give a long working time and allow adjustment of the brick slips.

  31. I need to raise a floor 10mm before putting down ceramic/stone type tiles. The floor surface is concrete screed. The area will be 10 meters square approx and will only be the product you suggest (no underfloor heating). I am concerned about it not cracking as its 10mm thick and if possible something that will dry in a day as its in my hallway and I will have no access once it is laid. The only other consideration is cost as its a large area.
    Thank you for your help.

    23rd September 2010

    Larsen Professional SLC1500 is a self-levelling compound for use up to 25mm and it would be suitable for this application. For 10m x 10mm you would require approx 8 bags.

  32. I need to screed an existing garage concrete floor to level (2-3mm) & apply decorative finish(can be resin based but needs to be coloured). Can you recommend a product?

    25th August 2009

    While a standard levelling compound may be suitable, I would recommend the use of Larsen Professional SLC 1500 as the levelling compound. This high quality leveling screed can be applied from next to nothing up to 25mm and will provide a very good finish for the application of decorative finishes.

    In terms of finish we have two suitable products -

    Polyfloor - a medium duty single pack floor paint

    WDC - a two pack epoxy coating offering superior wear resistance

    Both are avaialbel in red, light grey and dark grey as standard.

  33. I want to remove a stain caused by Copper Sulphate spill on concrete floor will hydrochloric acid based cleaner work ?

    3rd March 2015

    Acid based cleaners may help to remove copper staining, however, most copper salts are coloured and there may be a risk of spreading the stain further.

    Also, care must be taken using acid based cleaning products of cementitious surfaces as they may etch the surface.

    The best product we have to try is Extra Strength Remover in our tile maintenance range. This product is based on a blend of acids and special surfactants. 

    Always read the directions and carry out a small trial area first.

  34. I'm carrying out remedial works to a suspended timber floor (steel joists, 18mm ply, + 6mm ply cross boarded glued and screwed). I need to spot fill the screws heads and, fill the joints in the plywood with a suitable filler. All in middle of live A&E dept - so smell, fumes are an issue. Can you recommend a product? Regards,
    Dennis Brownlee
    07764313244
    (Belfast)

    4th October 2010

    We have a cement based filler which only needs mixed with water - Feather Edge. This is a fast setting, fine filler ideal for your application.

    For prices and further information contact Andrew Duffy a.duffy@larsenbuildingproducts.com

     

     

  35. I've been suppled with Larsen Flexible Floor Tile Adhesive by a tile supplier. Screed has gone down today. The screeder advised we'd need a specialised adhesive if we wanted to tile quickly, otherwise we'd have to wait 1 day /mm of screed until it was fully set, especially as we have underfloor heating installed. at 100mm od screed, we'd have over 3 months to wait. Is the adhesive supplied by the tile company suitible? If not, do you supply an adhesive that is suitible for tiling on screen after only a few days?

    12th August 2011

    When tiling onto a cement based screed there is no specific requirement that the screed is dry. The Code of Practice recommends that the screed be at least 6 weeks old. The reason for this is too ensure that most of the shrinkage of the screed has occurred and that the screed is of sufficient strength to withstand any further shrinkage stress withuot cracking (and therefore damaging the tile installation).

    There are 'green screed' tile adhesives available on the market claiming to allow tiling onto screeds at an early age. We do not produce such an adhesive as we feel it is important to tile onto a screed with of an age where the strength and quality of the screed and workmanship can be fairly assessed.

    Where Fast-Track projects require early tiling, we recommend the use of our Dry4 Binder or Dry4 Screed to produce a rapid hardening, low shrink screed.

  36. Our builder used screed to cover wet underfloor heating in our new kitchen extension 24 square metres. However,the floor level ended up too low. He has then suggested to use latex self leveling compound to elevate the floor before tiles are laid. Is this something you would recommend? I don\'t want to keep spending more money if this will fail.

    20th October 2014

    It is common to apply a levelling compound to a floor to adjust levels, flatness or smoothness before applying the floor finish.

    Our Latex Levelling Compound is suitble for use over underfloor heating systems.

    If the screed used is calcium sulphate based (which are common with wet underfloor heating systems) it must be dry (<0.5%), suitably prepared and primed prior to applying the levelling compound.

    If the level is to be increased by more than 6mm a different product should be used, perhaps SLC1550 Flex.

    If you require any further information call our Technical Dept on 02890774000

  37. There is currently a builders floor left on house hallway and this needs to rise 25mm. Can u advise what to put on the existing concrete floor to raise the level by 25mm prior to tiling

    15th May 2008

    The floor level can be raised by 25mm by the application of Professional SLC1500. This a single part self levelling underlayment which can be applied up to 25mm in one layer. Consult the product datasheet for application information.

    TDS - Professional SLC 1500

  38. we are carrying out fast track office fit-out and need to infill floor void at first floor level where stair has been removed. we are installing t-beams with insulation over and 75mm concrete screed to take carpet finish. we need floor dry as quickly as possible. what product would you recommend to reduce drying time.

    18th November 2009

    Instead of 75mm concrete screed, use Larsen dry4 screed, this is a proprietary hydraulic, rapid drying screed. It can be covered after 1 week.

    Alternatively, after placement concrete apply Larcote DPM (2-part epoxy dpm) onto concrete and SLC 1500 @ approx. 5mm.

     

  39. We are doing a tiling project and have to install over your SLC 1550 flex, can you confirm what we need to do to prepare it to receive the stone & porcelain tiles?

    4th January 2017

    When mixed and applied correctly SLC1550Flex does not require any further treatment before tiling.

    If the surface of the SLC1550Flex is buff coloured and/or dusty (usually as a result of excess water added during mixing) it would need to be mechanically buffed and primed.

  40. We are looking for a product to seal a painted concrete surface which would then allow us to lay ceramic tiles.

    23rd January 2011

    When tiling onto painted surrfaces it is very important to ensure the quality and bond of the paint is sufficient to support the tiling installation. Good quality gloss or epoxy paints may provide a suitable base for tiling, but cheaper floor paints and emulsion should generally be mechanically removed before tiling.

    If the paint is sound, I would recommend using Larprime EU. This is a two pack solvent free epoxy primer. After mixing apply to the floor with a roller and then while still wet apply a broadcast sand scatter of dry 16/30 sand at a rate of 2kg per sq. m. Leave overnight for the primer to harden and then brush or vacuum to remove excess sand. This will leave a sandpaper like finish to provide a mechanical key for tiling.

  41. We are proposing to use "Shake Top" hardner unto a new concrete floor that is been used to store scrap lead. It is possible that potential light acids might be present in the scrap lead, & leach unto the floor. Please advise if the hardner is suitable for said application?Will light acids cause a problem?
    Will the lead react with the hardner?

    2nd November 2010

    Shake-top provides a very hard wearing abrasive resistant floor. As it is cement based, the floor would need to be sealed to prevent damage from the acids. Suitable sealers include Acraseal or Larseal Impregnation

  42. We are renovating a domestic floor that has an existing pitch-epoxy surface DPM. Could you please comment on the suitability of Larcote PE pitch-epoxy for re-coating damaged and repaired areas, and then probably overcoating the whole floor with a final new surface DPM, before applying floor covering.
    Many thanks.

    20th September 2011

    Due to apparent state of the the existing coating I would recommend removing it by mechanical means, e.g. enclosed shot blasting or grinding, to expose the original substrate.

    I would not recommend applying our DPM over an existing pitch-epoxy coating.

  43. We have been asked to look at a solution to coat an existing internal concrete flagged floor with a product that will give slip-resistant properties to the flooring. Can you advise if you would recommend anything in particular and what problems may occur, if any, due to the fact that the base surface are flags, and therefore may be susceptible to a degree of movement

    7th December 2009

    With the floor being a concrete surface (albeit flags) the most straightforward option may be to simply mechanically roughen the surface either by grinding or enclosed shot blasting. This will give a profile to the floor which will improve slip resistance.

    In terms of a coating, either Larsen WDC or PE epoxy coatings can be applied with a sand scatter which again will provide a profile to improve slip resistance. In this case with the possibilty of movement in the flags it would be prudent to coat each flag indivually rather than the floor as a whole.

    For further information ring our technical sales on 02890535427.

  44. We have removed the existing Marmoleum Floor Covering over six flights of concrete stairs - the thread surface remaining has adhesive that is very difficult to remove without further damaging the concrete surface. We are proposing to lay a carpet on the stairs. Would you recommend the Larsen Latex Self-levelling compound as an overlay on the old glue/concrete surface as a preparation for the carpet?We note that some of your products can be laid on old adhesive.

    4th August 2015

    Normally we would recommend that 75% of adhesive residues are removed and anyhting remaining must be firm, stable and not water softenable.

  45. We have used the repel 38 product to seal floor surfaces. The client has now asked what product is best suited to be used to clean the floors without effecting the repel 38 sealer.

    30th May 2013

    The Repel 38 is an impregnating sealer and so lines the pores of the treated surface rather than forming a film on the surface. It improves both the hydrphobic properties (water resistance) and oleophobic properties (oil resistance) of the treated surface.

    Once the Repel 38 has cured then standard floor detergents, water etc can be used as normal. 

  46. What is the best way to repair a 0/3mm crack x 750 long in an under floorheating 90mm thick slab prior to tiling. The slab has been laid 10 months.

    27th November 2009

    Cracks in floors can be repaired with a number of products depending on the width of the crack. In all cases it is important to be sure that the crack is static otherwise it may reappear after the repair is complete. The options are as follows:

    Hairline cracks and crazing - Larsen Injection resin squeegeed into the cracks.

    Fine cracks up to ~5mm - Largrout EP

    Wide Cracks >5mm - Larfix E or Larsen Rapid Patch

  47. When using 1550 SLC in layers (for areas of deep fill), is it best to let each layer set fully, and then prime, or can additional layers be added during the setting period? Thanks

    5th September 2017

    SLC1550 can be applied in layers up to 50mm, with care or in small areas this depth can be increased. 

    Alternatively to fill deep holes, a clean 6mm aggregate can be added at the rate of 2 bags of SLC1550 to one bag of aggregate.

    Otherwise SLC1550 can be laid in layers allowing each layer to set fully then priming with 1 coat Acrylic primer diluted 1:1 followed by one coat neat Acrylic primer.

04 Tiling

  1. About 18 months ago our kennels concrete floor had a coat of latex followed by coat of garage paint, the paint is now coming off in patches....we would like to tile these areas with porcelain tiles - what will be the best way to prepare the floor and products to use for laying the tiles. The kennels although mostly covered are exposed to the elements.

    24th October 2014

    The best method would be to grind off the paint to fully expose the latex or screed. Then to tile using a Flexible (S1) adhesive, for best results to protect form urine etc, an epoxy tile grout should be used. 

    As an alternative Larsen Ultimate Flexible Rapid Set (S2) adhesive could be used if all loose paint was removed and Larsen Colourfast Tile Grout as the best of our non-epoxy tile grouts.

    For further information our Sales Manager in your area is Martin Colbey (07710864636).

     

  2. Are Larsen Standard and Fast setting tile adhesives suitable for direct application to aluminium heat spreader plates on underfoor heating systems?

    27th June 2011

    No, generally aluminium spreader plate underfloor heating systems are designed to be overlaid with timber floors. It may be possible to oversheet the heating sytem with a tile backer board which could then be tiled onto, but it would be better to discuss the options with the supplier of the heating system to get their recommendations.

  3. can i use brown floor grout on wall tiles

    16th November 2009

    Yes, but the joint must at least 4mm. As our floor grout contains sand great care must be taken when used with glazed ceramic tiles to prevent scratching.

  4. Can i use standard set flex to apply stone cladding its a kind of z clad to ply wood which has had a coat of paint applied?

    28th April 2015

    Unfortunately no.

    Neither the plywood nor the paint would be strong enough to support this type of installation. 

    Even if the paint was removed I would recommend using at least a tile backerboard of suitable thickness and checking with the board manufacturer.

  5. Can I use your flexible floor tile adhesive to tile a new floor over existing tiles?

    10th September 2008

    Yes, Flexible Floor Tile Adhesive is suitable for tile on tile applications.

    It is important to ensurte the existing tiles are firmly bonded and clean. It is advisable to thooroughly degrease the surface particularly if the floor is in a kitchen etc.

    Prior to tiling apply one coat of Larsen Acrylic Primer neat and allow to dry tacky before tiling.

  6. Can i use your Impregnating Sealer for marble and travertine tiles ?

    1st July 2011

    Impregnating sealer is suitable for any porous stone, concrete or tile. For Marble, Travertine etc we can also supply Larsen Professional Marble Protector

    Always carry out a trial area in an inconspicuous are or test the product on a spare tile before applying to entire floor to ensure the finish, appearance etc is accpetable.

  7. Can larsen flexible fast set tile adhesive be applied when the pva sealant on concrete floor is still tacky.

    21st December 2011

    We don't recommend the use of PVA as a primer for cement based tile adhesives. We would always recommend the use of Larsen Acrylic Primer when required with cement based tile adhesives.

    When applying the tile adhesive to the primer it is best to wait until the primer has dried clear but remains tacky, this is usually within 1-2 hours.

  8. Can you advise on a suitable product to remove fast set flex adhesive from limestone patio slabs laid indoors ? Thank you

    16th September 2017

    Unofrtunately this is going to be very difficult.

    The 2 things we would normally recommend are mechanical cleaning or an acid based cleaning chemical. Both of these run the risk of damaging the surface of limestone.

    All I can suggest is scraping and scrubbing with great care and perhaps trying a very mild, dilute solution of an acid based cleaner. However, this must be carried out with great care as acid will etch the surface of limestone. I would recommend to first carry out a trial in an inconspicuous area or on a spare tile first to ensure the tiles won't be damaged.

  9. Can you tell me if CTA Tanking Pack is suitable for use with underfloor heating (concrete screed)

    23rd November 2009

    Yes CTA Tanking Pack is suitable or use with underfloor heating. However, it is important to ensure the screed is fully dry and that the underfloor heating has been tested for a least seven days before applying the membrane. An alternative and better solution would be to use our new Seri-Dec Matting which will both tank the floor and prevent vapour pressure from building up in the floor.

    Gypsum based screeds must have a moisture content of less than 0.5% before covering.

  10. Can you tile direct onto WBP plywood or do you need to use a sealer ? I will be using the Larsen flexible tile adhesive.

    21st April 2009

    Yes. However due to the supply of inferior grades of plywood to the market recently, we recommend that the surface of the plywood is lightly sanded and then primed with one coat of Larsen Acrylic Primer.

    When tiling onto timber it is improtant to ensure that the floor is well supported and free form deflection. Plywood sheets should be ~18mm and screwfixed at 300mm centres ensuring there is sufficient support joist adn noggins and that all board edges are supported.

  11. Can your Impregnating Sealer be used to seal grout?

    18th August 2011

    Yes, Impregnating Sealer is ideal for sealing grout joints. If the tile is absorbent then I would recommend sealing the entire surface. If it is non-porous (e.g. ceramic) then wipe of any excess sealer from the tile before it dries.

  12. Could i use your stain resistant narrow joint grout on my glass mosaic kitchen wall tiles

    12th March 2012

    Yes Stain Resistant Narrow Joint Grout is suitable as long as the joint width is 4mm or less. Alternatively, for joint widths of 2-20mm, Stain Resistant Wide Joint Grout would be suitable.

  13. Difference between a CT2TS1 and a C2TSE1

    21st May 2012

    EN12004 Adhesives Classifications

    Type

    C    -               Cementitious

    D    -               Dispersion

    R    -               Reaction Resin

    Class

    1     -               Normal

    2     -               Improved with additional characteristics

    F    -               Fast Setting

    T    -               Non-Slip

    E    -               Extended Open Time

    S1  -               Deformable

    S2  -               Highly Deformable

  14. Do you have a product that can be injected to fill gaps under hollow floor tiles?

    9th October 2014

    Larsen Injection Resin is a fluid 2-part epoxy which would be suitable, however this will not necessarily correct any underlying fault.

  15. Do you have a product that is gypsum base for tiling onto a screed/ UF Heating floor

    30th July 2015

    We do not currently supply a gypsum based tile adhesive.

  16. Good Afternoon,\r\nI have just grouted an Indian limestone floor with grey GPM. The first day or so it looked grey. It has now effloresced so badly it looks like a pavement on a frosty morning. It is an extremely hard deposit and does not readily brush off. Solutions please, my client is not best pleased!Being limestone it is not feasible to use standard brick cleaner.

    23rd October 2014

    Unfortunately there are only two options to remove the efflorescence - mechanical cleaning or acid washing.

    As you say with the stone being limestone it is obviously prone to etching with an acid based cleaner. It is possible that if the limestone is sealed, a mild (or very dilute) acid based cleaner based on Phosphoric acid may work, but this would need to be done with great care so as to not damge the stone. I would recommend carrying out a number of trials with a spare slab to see the effect of the cleaner on the stone before starting on the floor.

    The other option which may be safer would be to use a more vigorous method of mechanical cleaning on they joints. 

     

  17. Having just had a Flotherm liquid screed laid 50mm for underfloor heating is there any further prep work required before laying floor tiles,it has been mentioned we now need to sand the surface as the adhesive may not stick to the smooth surface causing tiles to lift later?

    8th April 2014

    The follwoing lin is for our recommendations for tiling on gypsum screeds in general - Tiling on gypsum screeds

  18. Hello, I have recently grouted my bathroom floor tiles with your Colourfast 360 product. Do I need to apply any type of sealer to the dried grout?\r\nThanks.

    6th July 2015

    While Colourfast 360 is a premium quality grout, it can still benefit from the application of a suitable sealer like our Impregnating Sealer. This long lasting protection will further improve water repellency and reduce dirt pick up and risk of mould growth.

  19. Hello, please let me know if you Flexible Standard Set Adhesive is suitable for use with underfloor heating covered with concrete screed please?

    25th November 2011

    Yes, our Flexible Standard Set tile adhesive is suitable for use over underfloor heating.

    When using a standard setting product on floors please ensure sufficient time is allowed for the adhesive to harden before grouting or trafficking.

  20. Hi is the fast set flex adhesive ( in the orange bag) suitable for wetroom floors and walls \r\nThanks.

    6th December 2016

    Yes, this product is suitabel for use in wetrooms. As it is a fast set, care needs to be taken when used on walls to ensure tiles are placed within the open time of the adhesive.

  21. Hi there, what type of adhesive would we use for tile cladding which will be directly behind a wood burning stove?

    24th November 2014

    All of our cement based tile adhesives are tested after high temperature storage (70C) and so should be suitable. I would recommend using a flexible adhesive to cope with the thermal movement and take care to use a sufficient expansion joint on perimeters also.

  22. Hi \r\nCould you please advise me on the most suitable self levelling compound to just cover 3mm under floor heating cables that are laid on a 12mm ply floor which is covering 18mm floor boards. This is then going to be covered with a porcelain tile so I require a compatible tile adhesive too.\r\n Thanks

    18th June 2014

    SLC1550 would be suitable, applying a minimum of 6mm (10mm would be preferred). The floor must be suitably prepared and free from excessive movement. The tiles can then be laid using any flexible tile adhesive.

  23. How can I remove adhesive from the back of tiles so I can reuse them

    20th February 2010

    Tile adheisves are designed to exhibit a strong bond to most types of tile and as such cured adhesive can be very difficult to remove. In small areas, mechanical scraping or grinding may be successful.

  24. How long after tiling can underfloor heating ( wet ) be turned on? And in what increments of temperature?

    12th December 2016

    It is recommended to leave new tiling for 7-14days before turning on underfloor heating and this should be done gradually, typically increasing the water temperature by 5C per day.

  25. How much Larsen Flexible Standard Set Adhesive do I need for a 12 square metre kitchen floor?

    23rd October 2011

    3 x 20kg bags should be sufficient allowing for wastage.

    Take care as Larsen Flexible Standard Set will take 16-24 hours to harden before the floor can be trafficked and grouted.

  26. I am doing a tiling job in a train station onto a 12mm ply floor laid over 18mm t&g.What adhesive would you reccomend for a porcelian tile

    30th July 2008

    Our Professional Flexible Fast Set would be suitable for this application. It is imperative that the plywood is adequately screw fixed at 300mm centres and along edges. Ensure sufficient joists and noggins exist to prevent deflection and the underside of the floor is adequatley ventilated. The resulting floor must be free from excessive deflection prior to tiling. Consult the product datasheet and our Tiling Specication Guide before use.

  27. I am laying granite 600 by 600 paving slab with 10 mm gap in the garden.is it OK to use stain resistant wide joint grout for external use.

    5th June 2014

    Yes, Stain Resitant Wide Joint Grout is suitable for external use. Alternatively, if these are thicker slabs we also manufacture Streetscape GPM which is a gunnable pointing mortar.

  28. i am laying limestone tiles on plywood floor with under floor heating, do I need to turn off heating and if so ,why?

    23rd January 2010

    It is always recommended to turn off underfloor or undertile heating before tiling. If the heating system is left on during tiling the adhesive will set more rapidly which in itself may not be a problem, however there is a greater risk that the adhesive will have skinned over before the tiles are placed. This results in a reduced bond between adhesive and tiles and in the worst cases it can result in a total lack of bond.

  29. I am specifying a job and need your advice. It is a honed and filled travertine tile 60x40cm (very rough back) going down on sand/cement screed with underfloor heating. Grout width will be 4mm, colour ivory. What adhesive, grout and sealer is best?

    26th November 2009

    Adhesive - Larsen Professional Flexible Fast Set - White

    Grout - Larsen Professional Stain Resistant Wide Joint Grout -Ivory

    Sealer - Larsen Professional Marble Protector

    If the screed is very porous it would be worth priming with Larsen Acrylic Primer

  30. I am specifying a job and need your advice. It is an opaque 10mm thick polished marble tile 30x30cm going onto a wall around a shower, domestic use. The wall is sand/cement plaster on 100mm block. Grout width will be 1mm, colour grey. What adhesive, grout and sealer is best?

    26th November 2009

    Adhesive - Larsen Professional Flexible Standard Set

    Grout - Larsen Professional Stain Resistant Narrow Joint Light Grey

    Sealer - Larsen Professional Marble Protector

    It would also be worth considering using Larsen CTA Tanking Kit

  31. I am tiling a bathroom floor.\r\nI have an 18mm marine plywood floor. I have attached underfloor heating to the surface with the primer supplied and to allow the adhesive tape to stick. I have 600 x 600 porcelain tiles. I have the following LARSENS materials. Pink acrylic primer. SLC 1550 and Wooden floor fast set.\r\nI am confused as to how to use the primer.\r\n1. Do I use it neat or 1:1 on the plywood before the SLC 1550 and do I apply one or two coats?\r\n2. After I have applied the SLC and allowed it to dry. Do I use the acrylic primer again before using the wooden floor rapid set tile adhesive? If so how do I apply this?\r\n3. I take it applying Wooden floor rapid set to SLC 1550 is ok?\r\nI obviously need a flat surface and to skim the UFH before applying the tiles.\r\n4. Also as the adhesive is very rapid from what I have read, is it ok to mix enough for a few tiles at a time then once these are straight mix some more etc? It also states about how you need to twist the tile. Theres not going to be much twisting with a 2-3mm grout line!

    10th June 2012

    Firstly it is important to ensure the plywood has been screwfixed and is stable and will be free form deflection and also to ensure the undertile heating system is suitable for use on a plywood substrate.

    \r\n

    Then mix and apply the SLC1550 over the heating elements, again check the heating supplier\'s recommendations, but usually a few mm over the wires is sufficient to protect them from the tiling trowel.

    \r\n

    Allow the levelling compund to harden (usually overnight is sufficient) and apply one coat of the Acrylic primer pre-diluted 1:1 with water.

    \r\n

    The tiles should be fitted with a solid bed of adhesive ensuring as close to 100% coverage as possible between adheisve and tile. For best results use a thick bed solid bed trowel and back butter the tiels with a thin skim of adhesive.Do not use dots and dabs. A minimum of 3mm grout joint is recommended.

    \r\n

    I would also recommend, as there is undertile heating, leaving a larger perimeter joint where the tiles meet the wall etc and fill it with a silicone sealant or similar.

    \r\n

    It is ok to mix part bags of adhesive just keep the water ratio the same, approx 2.5L water per 1/2 bag of adhesive (10kg).

  32. I am using the flexible standard set adhesive and preping the wall first. I am also using the pink ready made acrylic primer. do i dilute it? or put on straight?

    23rd April 2009

    Larsen Acrylic Primer can be used as supplied without diluting.

    However, when using a cement based tile adhesive on a gypsum plastered wall it is neccesary to fully seal the wall to prevent a chemical reaction between the gypsum and the tile adhesive. This is best achieved by applying one coat of the primer diluted 1 to 1 with clean water. Allow this to dry and then apply one coat of the primer neat. Allow this second coat to dry before tiling.

  33. I am using your larsen flexible floor grout black and I run into a problem. My white ceramic tiles are smudged with black stripes after the grout is applied. What product(s) do you suggest I should use to clean them?

    11th September 2009

    Often it is simply a matter of cleaning the tiles with a mild acidic cleaner such as Larsen Professional Cement Remover with a plastic, non-scratch scouring pad.

    Always trial a small area first and protect yourself and sensitive surfaces when using cleaning products.

  34. I have a black limestone patio that needs sealing. Is your impregnating sealer suitable for use outside?

    6th July 2015

    Yes our Impregnating sealer is suitable for external use. As with all applications of Impregnating Sealer it is important to ensure sealer is not left to dry on the surface. This is best achieved by allowing the sealer to soak into the tile for approx. 15 minutes and then wiping any excess off the surface with a clean lint free cloth.

  35. i have a customer whos tiles have lifted off the floor. after inspecting the floor it seems that she has put a layer of varnish on the finished floor to keep dust down which proably lead to the tiles lifting. she now wants to retile the floor. is there anything i can put over the varnish or would i be better to remove the varnish. would flexibilzing the floor and throuwing sand on it letting it set and brushing off the excess ans then laytexing the floor be ok before tileing it again or not. please advise

    12th March 2010

    The best method would be to mechanically prepare the floor e.g. grinding back to a good quality absorbent substrate. It is worth noting that the floor may be of poor quality if it was initially 'varnished' to keep the dust down. An alternative option would be to use a decoupling membrane such Larsen Ser-Dec and leave the'varnish' in-situ.

  36. I have bought your NARROW grouting for my tumbled travertine tiles but find that the joints are nearer 7 mm. Can you suggest how I can still use this grouting? and what will be the problems, if I do?

    18th September 2010

    Our Stain Resistant Narrow Joint Grout is suitabel for use up to 4mm joint widths. Above this joint width there is an incresed risk of cracking of the grout and also it will be more difficult to attain a well filled grout joint.

    If you are forced to use the Narrow Joint grout at widths >7mm, the only thing which you could try would be to make the grout up stiffer than normal by mixing with less water. While this may help, there will still be a greater risk of cracking.

  37. I have had a bathrooms walls lined with Fermacell board preparatory to tiling. The tile fitter will be using your Showerproof adhesive, tiles are 152x152 British Ceramic, does the board need priming prior to application?\r\n\r\nMany Thanks

    5th February 2015

    The information provided by Fermacell suggests that priming is generally not required when tiling and the same is also true when using our Showerproof tile adhesive.

    We have not carried out specific tests on Fermacell boards but I do not believe priming to be necessary in this case. I would suggest your tiler carries out a few trials intiially removing a few tiles after placing to ensure there is adequate contact and coverage between tile and adhesive to enusre the adhesive has not prematurally skinned over due to the any absorbency of the board.

  38. I have had applied porcelain tiles around a bath tub tub with Larsen tile adhesive and grouted with another copmpanies grout, result stains on tiles. Help!

    29th October 2009

    While porcelain tiles are of very low absorptivity then often have microscopic pores in the surface. When grouted with a fine cement based grout these pores can become filled with cement film and pigments. This is particularly noticeable when the grout is of a contrasting colour to the tile.

    Often it is simply a matter of cleaning the tiles with a mild acidic cleaner such as Larsen Professional Cement Remover with a plastic, non-scratch scouring pad.

    Always trial a small area first and protect yourself and sensitive surfaces when using cleaning products.

  39. I have had two bathrooms and a cloakroom refitted. The fitter used Larsens professional tile adhesive and grout to fix the tiles. Unfortunately he used the 'Dot and Dab' method to fix the wall tiles. I note from your product advice this is not a recommended method. Can you tell me the problems that could occur from using the ‘Dot and Dab’ method of fixing tiles to the wall.

    28th November 2010

    Dot and Dab is not recommended as it generally results in the adhesive being applied thicker than the recommended application depth and in there being a relatively low coverage of adhesive on the tile. If the tiles are well bonded, there may be no real problem. Problems generally occur when dot and dab is used on floor tiling or in wet areas, where the recommendation is for 100% adhesive coverage to the the tiles

  40. I have installed yellow/beige coloured granite paving and want to use streetscape to grout.. can I get it in a sandstone/beige colour or can I use a cement colouring to get the desired shade ? Any suggestions welcome. Thanks

    27th October 2014

    Hi, we do produce our Streetscape FJM in Buff and as an alternative we also produce a gun pointing mortar Streetscape GPM in Buff and Yorkstone.

  41. I have just had anhydride screeded floor tiled with larsen flexible rapid set adhesive (screed sanded & primed with larsen acrylic primer). My query is how long should I leave the adhesive to cure before turning the (Wet)underfloor heating system back on. I understand that it should be turned on at low temp initially and ramp up gradually.

    11th February 2016

    With anhydrite or other calcium sulphate screeds it is imperative that moisture testing has been carried out and the screed is below 0.5% before tiling and that the underlfoor heating has been fully commisions as per BS EN 1264. 

    Typically we would then recommend that the tiling is left for 7days before heating is turned on and the temp intially increased by 5C per day.

  42. I have over applied your 'Tile,Slate&Floor Sealer' to ceramic tiles. Is there a product to strip same and do over? I'd really be very obliged for your assistance.

    10th July 2009

    Tile, Slate & Floor Sealer would be quite difficult to remove once dried as it is designed to protect the underlying floor from damage. Proprietary paint stripping products may be suitable to remove it, however always trial an incospicuous area first for compatability with the substrate.

    It is also worth noting that glazed ceramic tiles do not generally require the application of a sealer and indeed most sealers require a degree of porosity in the substrate.

  43. I have recently had a porcelain tile floor layed in our kitchen.How do we remove the residue of grout and adhesive and bring the surface to a high clean finish

    1st September 2009

    We supply a range of Tile Maintenance products to care for your tiling installations. Cement Remover and Extra Strength Remover are acid based cleaners in the range which will remove grout and adhesive residues. The floor can then be cleaned and maintained with Clean & Shine.

  44. I have regrouted a shower with Ivory Larson professional narrow joint grout. When the grout gets wet it changes to a darker colour. Is this to be expected? Does it need sealing?

    11th November 2015

    Tile grouts are designed to resist water ingress by having a low rate of water absorption. Generally there will still be a small amount of water absorption which will typically darken the grout while it is wet. This is more noticable on certain colours, particularly ivory and beige. 

    This can sometimes be worse if the grout has been mixed with too much water or had excessive water used during cleaning.

    The application of Larsen Stone and Grout Protector or Larsen Impregnating Sealer will further reduce the amount of water absorbed and hence the degree of darkening.

  45. I have removed vinyl tiles from a concrete floor and there is "cutback" adhesive left on the concrete. Do you have any ceramic tile adhesive that is suitable for use over "cutback" without having to remove the cutback from the concrete?

    23rd July 2010

    Cutback is an old type of adhesive which is based on bitumen. While cement based tile adhesives (particularly flexible grades) will probably bond well to the old adhesive, as it is bitumen based and inherenetly 'soft' we typically find that failure will occur within the old adhesive. All cement based materials will shrink to a degree on setting and this can create enough force to shear the old bitutmen based adhesive.

    Our recommendation would be to remove the old bitumen based adhesive until there is at least 75% of the original, uncontaminated concrete showing, before attempting to fix ceramic tiles.

  46. I Have started to tile a shower area with ceramic glazed tiles and have noticed that while cutting them with a wet diamond cutter the water soaks into the red clay backing and is visible through the glazing. I know that I can seal the grout joint but my worry is that because the glaze only lipps the edge by about 1mm any water ingress however small will be visible once the job is completed. My Question is can you seal the edges of the tile before grouting without it staining through? Then seal once again after grouting.\r\nWhat product would you recommend for this purpose? \r\n\r\nThanks.

    7th September 2015

    Our Impregnating sealer is a solvent based water repellent and should be suitabel for this application. Usually a similar approach is used when grouting some natural stone tiles to reduce the incedence of picture framing. 

    I would recommend carrying out a trial area first to ensure suitability.

  47. I have tiled a shower cubicle with Travertine tiles. Can I use Larson Marble Protector to seal the tiles and repel water.\r\n\r\nThank you for any advice.

    31st December 2012

    Larsen Stone & Grout Protector (previously marketed as Marble Protector) would be suitbale for use in this application and will greatly reduce water penetration into the tiles and grout. This product does not replace the need for a suitable secondary tanking system in wet areas.

  48. i need a adhesive fo fix some brick slips to the exterior of my house, i beleve i used some larsen quick dry floor tile adhesive a few months ago and on the packet am sure it said i could use it for brick slips,if i am wrong what can you recomend thanks

    19th February 2010

    Our cement based tile adhesives are suitable for use externally and would be ideal for fixing brick slips. It is probably better to use a Flexible (S1) standard setting product e.g. Larsen Professional Flexible Standard Set. This will give a long working time and allow adjustment of the brick slips.

  49. I over applicated larsen impregnating sealent on slate floor. Is there anyway to remove the black blotches. Acetone for example

    9th April 2009

    Unofrtunately there is no easy way of removing Impregnating Sealer.

    It is worth mentioning however, that it is unlikely that the Impregnating Sealer has caused the blothces (unless a very large over application). It is more likely that the sealer has merely highlighted some of the natural variations in the slate.

  50. I will be tiling a concrete floor(600m) that had previously been carpeted. We have removed the carpet and underlay but there are patches of glue resin still on the floor. Will primer and flexable ahesive work. (What kind?)

    13th July 2016

    Unfortunatley not. It would be recommeded to remove all existing glue from the floor before tiling.

    Carpet adhesives are quite soft and while the tile adhesive will likely bond to the glue, the stresses undergone by a tiling installation are generally suffiicent to cause a failure in the glue.

    If the majority of the floor is clear of glue residues and those reamaining are hard, sound and not water softenable, then a Latex Levelling Compound could be applied over the floor prior to tiling.

  51. I've been asked by a client to tile a large exterior balcony area which was finished with roof grade asphalt. Do you have a product (eg. a decoupling membrane)which would gaurantee that the tiles would not lift due to the expansion and contraction in the asphalt.

    14th August 2011

    It is impotant to ensure that a balcony finished with roofing grade asphalt is structurally strong enough to be used as an outdoor living space.

    Unfortunately, we do not have a decoupling membrane available at the moment, I suggest you contact Schluter systems.

  52. Is it neccesary to seal matt porcelian tiles,if so do you seal before or after grouting.what product do you recommend .

    30th March 2012

    Normally it is not necessary to seal porcelain tiles before grouting due to their very low water absorption characteristics. Occasionally the porcelain contains micro-pores on the surface and these can become filled with cement and pigment during grouting. It is usually only obvious on light coloured poished porcelain with dark coloured grouts.

    To help prevent this from occuring seal the surface of the tile with Impregnating Sealer before grouting. Apply a very thin layer uniformly with a cloth, brush or sponge and allow to penetrate for approximately 15 minutes. Then remove all excess product from the surface by polishing with a clean lint-free cloth.

  53. Is Larsen Professional Stain Resistant Narrow Joint grey grout suitable for grouting porcelain laid on plywood?

    25th May 2010

    Larsen Stain Resistant Narrow Joint Grout is flexible and therefore suitable for grouting tiles suitably laid on correctly prepared timber substrates.

  54. Is Larsens flexible standard set used for grouting and setting tiles

    5th February 2010

    No, Larsen Flexible Standard Set is a tile adhesive and is only suitable for fixing tiles, it is not suitable for grouting. We have a full range of tile grouts specifically designed for grouting applications.

  55. Is there a solent that would help remove GPM grout from the surface of a Slate tile\r\nthank you

    26th April 2017

    A mild acid based cleaner is normally sufficient with a little scrubbing. We have CemClean which can be diluted for use. Alternatively, tile shops will retail extra strength removers or grout remover and these may also be suitable.

    I would always recommend trialling a small area first to ensure the natrual stone is not damaged by the celaning product.

  56. My customer has bought a cement based tile adhesive made by yourselves. He has a gyvlon flow screed floor. Do you supply a epoxy primer to be used inbetween the two ?

    1st December 2009

    When tiling over an anhydrite floor screed, we recommend the following:

    1. The floor should be dry - less than 0.5%. Underfloor heating if present should be tested for 7 days prior to tiling (this will also help to ensure the screed is dry).

    2. Any laitence (scum) should be removed from the surface by brushing or sanding.

    3. The surface should be primed with one coat of Larsen Acrylic primer diluted 1:1 with water followed by one coat of Acrlyic primer applied neat.

    The following is a link to our specification

    Tiling onto gypsum screed

  57. On the front bag of the stain resistant wide joint grout it states is for joints from 2 to 20mm. On the reverse of the bag it says use in joints from 3 to 20mm. For joints less than 3mm use narrow joint grout. Could you tell me which is correct. Thanks

    10th June 2014

    Stain Resistant Wide Joint is suitable for use in joints from 2 to 20mm in width. 

    Stain Resistant Narrow Joint is suitable for use in joints up to 4mm in width.

  58. Please can you advise a suitable preperation for plaster skim on walls before tiling in a shower area, I will be using larsen cement based adhesive and professional wide joint grout on travertine tiles.

    19th July 2011

    The first thing to check is the weight per square metre of the tiles. Plaster skim is only suitable to support around 20kg per square metre of tile and adhesive. If your tile and adhesive is going to be more than this then we would recommend either using a different tile or mechanically fixing a suitable tile backer board to the wall.

    Assuming the weights are ok then it is best to use our Tanking system in the shower area prior to tiling. This is a paint on membrane and tape system which is suitable to receive tiling with a flexible cement based adhesive after 24 hours.

     

     

  59. Please can you email me a specification for laying stone tiles directly on top of the Larsen DPM Universal product. We assume the floor is an existing concrete slab but can verify if there is a DPM. Many thanks

    24th October 2014

    Normally, a levelling compound is applied over the DPM prior to floor finishes being applied and this can be tiled normally.

    If levels etc restrict the installation of the levelling compound, the DPM can be laid as a two coat system with the second coat fully broadcast with a dry sand, this leaves a sandpaper like finish with good mechnaical key which can accept direct application of the tile adhesive.

    Apply first coat of DPM (red) at up to 20m2/5kg pack and allow to cure for 8-24 hours.

    Apply second coat of DPM (yellow) at up to 25m2/5kg pack and fully broadcast with dry 16/30 sand at a rate of 1.5 -2kg/m2. Allow to cure overnight and then remove excess sand by vacuum. The surface should have a sand paper texture and is now ready to receive tiling.

  60. Please can you let me know what adhesive and grout I need for pebble
    tiles in swim pool?

    18th November 2010

    Either Larsen Professional Flexible Fast Set or Flexible Standard Set adhesives would be suitable. For the grout, I would recomend Larsen Epoxy Tile grout.

  61. Should I prime a plasterboard wall before tiling with travertine tiles (305mm x 305mm) and using your fast set white adhesive. The plasterboard is the green stuff used for bathrooms.

    24th June 2011

    Generally plasterboard (which has not been skimmed) does not require priming.

    It would be advisable to check the weight per square metre of the tiles as plasterboard is only recommended for use with tiling up to 32kg per square metre (including the weight of adhesive - approx 4kg per square metre).

  62. The grout that I have purchased states on the packaging that it is for joints of 3 to 20mm however I have elected to tile at 2mm joint spacing. I note that your latest product indicates that it can be used for 2mm joints. Can you please advise if the grout I have will be suitable for 2mm joints or will I need to purchase more? The tiled areas include floor, walls and shower cubicle.
    Mant thanks.

    12th March 2010

    We are currently updating the packaging on our Stain resistant grouts. Larsen Professional Stain Resistant Wide Joint Grout is suitable for use in joints of 2-20mm.

  63. We are doing a tiling project and have to install over your SLC 1550 flex, can you confirm what we need to do to prepare it to receive the stone & porcelain tiles?

    4th January 2017

    When mixed and applied correctly SLC1550Flex does not require any further treatment before tiling.

    If the surface of the SLC1550Flex is buff coloured and/or dusty (usually as a result of excess water added during mixing) it would need to be mechanically buffed and primed.

  64. We are looking for a product to seal a painted concrete surface which would then allow us to lay ceramic tiles.

    23rd January 2011

    When tiling onto painted surrfaces it is very important to ensure the quality and bond of the paint is sufficient to support the tiling installation. Good quality gloss or epoxy paints may provide a suitable base for tiling, but cheaper floor paints and emulsion should generally be mechanically removed before tiling.

    If the paint is sound, I would recommend using Larprime EU. This is a two pack solvent free epoxy primer. After mixing apply to the floor with a roller and then while still wet apply a broadcast sand scatter of dry 16/30 sand at a rate of 2kg per sq. m. Leave overnight for the primer to harden and then brush or vacuum to remove excess sand. This will leave a sandpaper like finish to provide a mechanical key for tiling.

  65. We are proposing to use the Larsen Flexible Rapid set + on a concrete screed. The concrete has been poured 4 weeks. Is this sufficient curing time or is there a more accurate way of checking this in terms of the moisture content required.

    26th October 2016

    The crrent British standards do not offer recommendations in terms of moisture content but do recommend that new concrete is a minimum of 6 weeks old before tiling.

  66. We have used your Stain Resistant Narrow Joint Grout between the 25mm mosaic tiles lining a swimming pool. We note that you recommend leaving the grout for 3 weeks before filling the pool. Unfortunately, because of the high water table, it is not practical to leave the pool empty for that long. Can you say what the effect will be if we fill the pool after a few days please.

    12th February 2011

    It is necessary to leave the grout for a minimum of 3 weeks before filling the pool to allow the grout to achieve sufficient strength to resisit wash out from the joints and resist stresses in the structure which may occur on filling.

  67. What is the minium size grout joint with porcelain 45x45cm rectafied floor tile?

    9th September 2011

    Typically tiles of this type would be fitted with a very narrow grout joint of maybe 2mm. For this application we would recommend using our Professional Stain Resistant Narrow Joint Grout.

    It is recommended to give greater consideration to movement joints, even in domestic situations when instally large format tiles with narrow joints.

  68. Where in Wakefield, west yorkshire stocks larsen grout ?

    2nd July 2011

    If you call our Sales Manager Martin Colbey (07710864636), he should be able to locate your nearest stockist.

05 Repair

  1. A screed in a plantroom has broken up due to the vibration of pumps. The pumps are being replaced and put on anti-vib mountings, but what product is best suited for repair to the screed.

    22nd June 2009

    Hevy duty floor repairs in areas subject to vibration are best carried out with an epoxy product. For small area repairs use Larsen Epoxy Concrete Repair Kit. For larger areas or reinstatment of the screed as a whole use Larfloor HDS epsoxy screed.

  2. Advised that sandblasting too harsh to remove paint off sandstone around church windows, can you suggest another way?

    9th February 2010

    I would suggest a chemical paint remover. Unfortunately, this is outside our product range

  3. Can I use plaster weld or weld Crete on damaged wood to build plaster or structolite on it?

    19th October 2016

    I think you have come to the wrong 'Larsen' website. I think you need to visit  www.larsenproducts.com

  4. Can you advise how to repair a section of an insitu reinforced concrete bay window lintel which has spalled of concrete to the exterior vertical face and soffit exposing the reinforcement bar for approx 1.2m along its length. The height of spall is approximately 150mm and 60mm deep. Note the reinforcement is badly corroded so a treatment to prevent a re-occurrance would be required.

    25th March 2009

    Mechanically remove all loose and friable concrete and wire brush or similar the rebar to remove corrosion. Ensure the surface is free from dust and other forms of contamination. Ensure the rebar and concrete is of sufficient structural integrity to fulfil duty.

    Mix and apply Larcem RP to the exposed rebar and allow to harden. Mix and apply Larcem PA to the entire exposed surface and while still tacky (within approx 15min) apply Larcem 1450 Lightweight Repair Mortar.

    When the 1450 has sufficiently hardened, Larcem Fairing Coat can be applied to give a smooth uniform, durable finish.

  5. Can you advise on the suitability of using Larsen Quickset in a high moisture area on a ships deck. We have concerns about the flexibility of the product in that it will not provide sufficient flexibility as the repair thickness on the ship is approximately 50mm thick and will be placed down on top of steel deck plates. Can you confirm whether this product has an IMO certification?

    19th December 2013

    Firstly Quickset does not have IMO certification.

    Secondly, Quickset is not a 'flexible' product but does have a high flexural strength of approx 9MPa, so is much stronger in flexure than a screed or concrete.

    If you require any further information, phone our office on 02890774000 and ask for Technical Sales.

  6. Can you recomend a water repellant for a old stone built house that has been plastered on the outside. We would like something that we could apply by brush to the plaster.

    2nd July 2014

    We have several products which could be used all of which must be applied to bare (not painted) render. Suitbale products include Water Repel, Repel N and Repel 38.

  7. could you tell me your best product to repair concrete that the frost or grit has taken the top off some parts are maybe 8to 10 inches long and 1/2 in deep some are 2 or 3 ins by1/4 if you could tell me your best product i would be most grateful.

    15th March 2011

    Firstly it is important to remove all loose or friable material until a solid surface is reached. Then Larsen Professional SLC2050 External self-levelling compound can be applied.

  8. Hi there,- in the tech datasheet for larcem 25 SBR it is recomended that chemcrete 100+ be used as a super plasticiser when producing microconcrete. would there be any problem using chemecrete HP3 super plasticiser in its place?

    12th January 2012

    Chemcrete HP3 superpalsticiser is also suitable. Make sure the superplasticiser and the SBR are added separately to the mix.

  9. Hi, I'm looking for a product that will seal running water through a small gap in a concrete block wall. The water is running from the water table into the outlet side of a septic tank. Would you stock a suitable product?

    4th November 2008

    Larsen Leakplug is a ultra quick setting (~60 sec), waterproofing compound for repairing water leaks. When mixed with water a paste is produced which can be used to seal water leaks in concrete, rock, blockwork, brickwork, manhole rings etc. It is ieal for use to stem the flow of leaks before tanking takes place with Larpruf CG, Larsen 3:1 Tanking Mix or a Larsen Integral Waterproofer render.

  10. I am looking for a product to seal a 15 mm gap between a first floor patio and a external wall

    29th January 2010

    A flexible sealant should be used either Polyurethane LM 15 or MS-Polymer (Bond & Seal)

  11. I am renovating an old red brick house that has some structural cracks. What grout do I use to repair the cracks with?
    Also an old I beam is rusting. What product can I apply to retard the rust?
    Thanks

    29th April 2009

    Structural cracks in a house should be fully investigated by a professional surveyor prior to carrying out any repairs. Depending on the cause, nature and size of cracks there a number of options as to which product/method to employ. At the simplest, the repair required may be only aesthetic and the most severe the wall may require 'stitching' or the wall needing underpinned. Until this is known a product cannot be recommended.

    Depending on the location of the I beam the simplest option may be to blast or wire brush back to bare metal and then painting the beam with something like Black Bitumen Paint.

  12. I currently have external ceramic tiles which are beginning to lift. Have you any adhesive and grout which is suitable for external ceramic tiles which are on a concrete base?

    30th March 2010

    All our cement based tile adhesive are suitable for external use, however due to the risk of thermal expansion we would always recommend using a flexible tile adhesive exteranlly, e.g. Larsen Professional Flexible Fast Set.

  13. I have concrete imprint on my driveway.The paint has lifted/flaked in areas and
    I want to re paint it.The colour is black.Where in Ashbourne,Co.Meath ,Ireland are the stockists of Larsen's paint/sealer?

    12th July 2010

    Normally, printed concrete driveways are not painted, rather the concrete is coloured and then the surface is sealed with a product such as Larseal Super or Larsen Acraseal. We do not sell coloured paints or coloured sealers for this application. For details of where Larseal Super or Acraseal can be purchased contact our Dublin Office on 018348255

  14. I have rising damp in the corner of a bedroom in my house. I have read that if I drill 12mm holes @ 100mm centres below the floorboards and fill with a liquid/mastic type DPC this will stop the damp rising. Do you have a product such as this?

    16th April 2012

    Where rising damp is suspected it is best to seek the advice of a surveyor or other suitable professional as it is important that the source of the problem is being treated.

    We can supply a liquid DPC for injection, but agian this procedure is best carried out by a professional

  15. Is there a way I can treat old red bricks on my gable wall to prevent them from crumbling further?

    27th March 2015

    Unfortunatley we do not have any products which would repair crumbling bricks. However, crumbling bricks are usually a result of freeze thaw damage as a result of water ingress. Treating the bricks with a water repellent like Larsen Storm Repel will prevent further water ingress, while still allowing the bricks to dry out, this should reduce further damage as a result of freeze thaw.

  16. Loose pointing in joints of patio . Can I use a gun grade mixture to re fill joints ?

    31st March 2015

    Yes, Larsen GPM is an ideal product for repointing paving joints. It is worth considering why the original joints are loose before repointing.

    If the paving is laid in a flexible construction, e.g. unbonded on a bed of compacted sand, then the use of a rigid joint material like GPM would not be recommended. In this type of construction the paving can move over time and this can lead to the cracking of a rigid joint material.

     

  17. My garage window lintels are badly worn and water is penetrating. How do you recommend repairing or sealing?

    15th August 2011

    The lintel could be repaired / refaced with or Feather Edge or Rapid Patch repair mortars. Or sealed with Larsen Water Repel or if dusty and friable Larsen Impregnation epoxy sealer.

  18. Our property brickwork needs pointing. \r\nIt is most likely Victorian built, wish to match existing mortar and do DIY.\r\nWould like to match colour and mix proportions. \r\nAre you able to advise.

    6th July 2016

    With a period property it is generally advisable to replace like with like. In the case of repointing, the orginal mortar in a Victorian building would typically have been a lime mortar which is more tolerant of movement and more breathable than a modern cement mortar. 

    Generally in this case sourcing a sand similar to the original is sufficient to get close to the original colour, but this can be tweaked with the addition of small amounts of pigment.

    Unfortunately, we do not supply lime mortars, however, you may be able to get more advice from www.lime-green.co.uk 

     

  19. Repairing plaster around old windows. Is SBR Bond (Larcem 25) suitable?

    26th November 2011

    SBR Bond (Larcem 25) can be used both in the render and as a priming slurry to greatly improve the adhesion and durability of any repair.

  20. The builders had just left my house after laying a 25m2 concrete screed \r\nthen the dog escaped we now have a patio which is a mess . Covered in holes paw prints scrapes etc these range from 25mm deep prints to 3mm scratches. I would like a outside product that I could floot across the patio that would fill the holes and make everything in my world ok again\r\nmy biggest problem is the patio runs away towards a drain \r\nmany thanks\r\nSterling groves

    23rd September 2015

    There are a few of options.

    We have a patch repair product called Rapid Patch which could be used to skim over the paw prints etc. While this is close in colour to concrete the repairs may still be visible.

    Another option is SLC2500 which is a external levelling compound. With care this could be mixed slightly stiff to allow for the falls.

    Finally, a thin section (10-15mm) polymer modified screed could be applied incorporating Larsen SBR Bond. This would be trowel applied like a traditional semi-dry screed.

    If you would like to discuss further contact our Technical Sales on 07710864631. 

  21. the entrance into our transport yard is approx 7 meters wide with an automated gate which runs on a recessed channel. This area is subject to heavy traffic and subsequent vibration. Could you recommend possible solutions to what type of screed would be suitable for this application.

    5th January 2015

    I think the best option would be to use our Highways RRC15 which is a fast set, high early strength rapid reinstatement concrete which can be trafficked after 3 hours.

  22. We have a project where damp is penetrating a period home 225mm solid brick wall construction. We are lining walls internalls, but do you have a spray on invisible product to apply to the bricks externally to waterproof them?

    16th May 2011

    Larsen Water Repel is a solvent based metallic stearate solution designed for wateroofing brick, block and natural stone.

  23. What is the best way to repair a 0/3mm crack x 750 long in an under floorheating 90mm thick slab prior to tiling. The slab has been laid 10 months.

    27th November 2009

    Cracks in floors can be repaired with a number of products depending on the width of the crack. In all cases it is important to be sure that the crack is static otherwise it may reappear after the repair is complete. The options are as follows:

    Hairline cracks and crazing - Larsen Injection resin squeegeed into the cracks.

    Fine cracks up to ~5mm - Largrout EP

    Wide Cracks >5mm - Larfix E or Larsen Rapid Patch

  24. What is the best way to repair a concrete silo floor, we can only have a total thickness of new material of 50mm,on top of the existing reinforced concrete,which is worn, and has a lot of 20mm exposed aggregate

    4th March 2010

    A pumpable self levelling compound could be used (Professional SLC 1900) or alternatively a cheaper option would be to use a polymer modified screed bonded to the existing concrete. This can be achieved with Larcem 25 (SBR Bond).

  25. What would I use to stop paint flaking off a plastered dwelling house wall?

    16th March 2015

    There are a number of reasons why paint may flake off a plastered wall - if the wall was damp when painted, has subsequently got a damp issue, if the surface is dusty or alternatively if the surface was highly polished.

    It is important to remove all loose paint and then assess the surface to determine the underlying issue. Depending on the assement a specialist primer may be required which is compatible with the paint.

  26. What would you recommend for a concrete cast in situ garage roof! It would be good to remove a depressed (puddle) are to prevent pooling at the same time. Thanks.

    10th February 2014

    The easiest option would be to use a self-levelling compound to level the surface.

    If the levelling compound will be exposed to the elements, the product to use would be SLC2500 which is suitable for external use.

    If it will be protected from the elements and dampness then SLC1550 would be suitable.

  27. which product sholud i use to repair smooth faced contrete lintols

    10th May 2012

    Rapid Patch, Feather Edge and PRM would all be suitable.

06 Screeding

  1. A section of a concrete floor requires a self levelling screed which is allow for a depth of 12mm in places?

    10th August 2011

    Larsen Professional SLC1500 is suitable for use from feather edge to 25mmm and should be suitable for you application.

  2. After mixing SLC 1550 Flex, how long can it stay in the bucket for before it needs pouring onto the floor? Some suppliers say 30 minutes, others say 60 minutes. I need to apply 53 bags, so I need an accurate figure. Is there any way of extending the time?\r\n\r\nWhat is the recommended RPM for mixing SLC 1550 flex?\r\n\r\nFor SLC 1550 flex, your instructions state mixing for 1 to 2 minutes. Does that time start from when the powder first hits the water, or does the time start after the last of the powder is poured into the water? Worried about overmixing here. Can it be overmixed?\r\n\r\nFinally, I am self levelling a concrete subfloor that slopes down to 30mm. I want to do this in 2 layers, with the deepest section being the first layer. This will mean that the leading edge will not be 3mm thick (as required for SLC 1550) on the first layer, but will be covered with another layer once it is dry. Is this a problem?\r\n\r\nMany Thanks

    11th September 2017

    SLC1550Flex will remain workabble in the bicket for around 30min depedning on site temperature. We do not recommend adding anyhting to prolong this time.

    Normal paddle mixers or mixer pumps are suitable for mixing. Time of mixing is not ciritical as to some degree it is dependent on the type of mixer. It is improtant that it is fully mixed to  a lump free fluid consistency. This generally takes 1-2 mins with a paddle mixer, but quicker with a mixer pump.

    The minimum thickness of SLC1550 is due to the coarseness of the sand in the product. 3mm is the minimum recommended thickness.

    When applying in layers it is recommend to prime the first layer to reduce air release and bubbling of the second layer.

     

     

     

  3. Can Larsen 1500 SLC be laid onto WBP plywood to make up floor levels so the actual depth of fill is less than 25mm?

    25th June 2010

    Larsen Professional SLC1500 is only recommended for use on solid substrates such as concrete or screed. For application onto suitable fixed and prepared plywood we would recommend the use of Larsen Professional SLC1550 which is a fibre reinforced leveling compound. To further strengthen the floor a reinforcing mesh can be laid into the product.

  4. Can Larsen Latex Self Leveling Compound be used as a floor covering between a ground bearing slab and suspended slab with a step of 25mm between each.

    14th October 2014

    Larsen Latex Levelling Compound can only be used up to depths of 6mm and so would not be suitable in this application. However, SLC1550 Fiberflex is a fibre reinforced self-leveller and is suitbale for use up to 50mm depth and should be suitable in this application.

    Neither Latex Levelling Compound or SLC1550 are suitable as a final wearing finish. If a final wearing finish is required SLC2000 Industrial should be used.

  5. Can latex screed be laid on top of vinyl tiles containing asbestos (old Marley style tiles) before carpeting?

    22nd December 2016

    Latex Levelling Compound has not been tested as an encapsulation method of dealing with asbestos. If there is a risk of asbestos release from this flooring it is recommended to take specialist advice.

    In terms of the product adhering to vinyl tiles, there is normally no issue when the tiles are clean and free from dirt, polish etc. The bond can be further improved by priming the tiles with Larsen Primer Grip 360.

  6. Can you please tell me if your latex self levelling screed can be used on a floor which has a \"powdery\" existing screed approximately 1mm thick over a concrete base. I intend laying vinyl tiling over the top.

    4th February 2014

    Unfortunately, it will be the same answer from all suppliers - the latex levelling compound will only stick to the powdery surface and this will not be sufficently strong. 

    It is therefore necessary to mechanically prepare the floor (grinding or shot-blasting) then vacuuming to remove the powdery layer and create a sufficiently strong substrate for the levelling compound.

  7. Can you recommend a liquid DPM in place of the visqueen loose laid sheet DPM we had previously specified.

    17th August 2015

    Larsen DPM is a two part epoxy DPM. When applied in two coats it can be used where a structural DPM is not present.

    For further information contact Andrew Duffy, Technical Sales a.duffy@larsenbuildingproducts.com 

  8. Can you tell me if any of your self levellers can be used outdoors.

    26th March 2012

    Generally our self-levelling compounds are not suitable ofr use externally. In some instances it may be possible if the leveller will only experience intermittant water contact. We do have one self levelling compound SLC2500 which is designed for use externally. For further information, contact Technical Sales on 02890535446.

  9. Could you please let me know if it is possible to use Professional SLC 1550 Flex to level out an uneven OSB flooring?rnAs the OSB is bonded together with wax and synthetic resin adhesives, I was wondering if it could cause problems later.

    24th February 2015

    As you say, OSB can cause issues both due to the possibilities of wax etc interefering with the bond of any subsequent materials and the risk of swelling or delamination as a result of changes in moisture.

    For these reasons we normally recommend oversheeting OSB with either WBP (or marine grade) plywood or a cement backer board.

    In small, non-critical areas the surface of OSB can be sanded to remove any surface wax or resin and primed with our NP Keycoat, but you must satisfy yourself that the bond is sufficient and there are no barriers to adhesion.

    As with all timber substrates, the floor must be free from deflection and all edges (long and short) of boards must be supported along their length by joists or noggins. The underside of boards should also be sealed to reduce moisture effects.

     

     

     

     

  10. Could you please provide advice on laying SLC1550 at depths greater than 30mm. We have taken some walls down and the height difference between rooms requires levelling. The existing concrete screeds vary in height from 5mm to 38mm in some areas.

    1st November 2016

    Usually the best approach is to first fill in deep sections to within 5-10mm from the level you are trying to attain. Allow product to set and harden overnight. Then apply a 5-10mm layer over the entire area (priming etc as required).

     

     

  11. do we need to use a special latex screed on top of a floor treated with the speedo accelerator

    29th September 2009

    No. Once hardened, Speedo screed can be treated as any other, so any common levelling compound may be used.

  12. Do you have a floor screed product that canbe laid 40 thick on board insulation?

    9th July 2009

    Depending on the application there are a few options. If it is a domestic situation, typically with underfloor heating and a flowing screed is possible, I would recommend Larsen floTherm Liquid Screed.

    Alternatively, for a fast drying semi dry screed, Larsen dry4 Binder (with the inclusion of Larsen Fibrescreed) can be mixed on site and laid like a traditional screed.

  13. Having just had a Flotherm liquid screed laid 50mm for underfloor heating is there any further prep work required before laying floor tiles,it has been mentioned we now need to sand the surface as the adhesive may not stick to the smooth surface causing tiles to lift later?

    8th April 2014

    The follwoing lin is for our recommendations for tiling on gypsum screeds in general - Tiling on gypsum screeds

  14. Hi. potentially we are required to level a floor with an indentation of circa 30mm. Can you please advise on the maximum a self levelling screed can be laid in any one operation and appropriate drying times? Thank you

    19th October 2016

    SLC1550 may be applied up to 50mm deep.

  15. how do i mix the Flotherm liquid floor screed.

    10th October 2011

    Flotherm liquid floor screed can be purchased readymixed from numerous concrete suppliers throughout the island of Ireland.

    For site mixing use a good, clean screeding sand free from lignite and with a low organic content and mix.


    A typical starting point mix design is:
    600kg Flotherm Binder
    1200kg sand (dry weight)
    330L water (total water)

    The flow should be checked before pumping commences and should be in the region of 230-250mm.

    Mixing can be carried out with a suitable pump mixer.

    For more information contact our Technical Department

     

  16. I am looking to specify a levelling screed over a mixture of old glazed floor tiles and uneven tile adhesive. All loose tile adhesive has been removed - whats the best product and how soon could I lay a solid floating wood floor on it after it is laid ?

    4th August 2014

    SLC1550 is probably the most suitable levelling compound and can be laid up to 50mm in depth. Depending on site conditions and depth of levelling compound a wooden floor can typically be applied within 7 days, however it is always prudent to carry out moisture checks before laying any wooden floor.

  17. I am tiling a bathroom floor.\r\nI have an 18mm marine plywood floor. I have attached underfloor heating to the surface with the primer supplied and to allow the adhesive tape to stick. I have 600 x 600 porcelain tiles. I have the following LARSENS materials. Pink acrylic primer. SLC 1550 and Wooden floor fast set.\r\nI am confused as to how to use the primer.\r\n1. Do I use it neat or 1:1 on the plywood before the SLC 1550 and do I apply one or two coats?\r\n2. After I have applied the SLC and allowed it to dry. Do I use the acrylic primer again before using the wooden floor rapid set tile adhesive? If so how do I apply this?\r\n3. I take it applying Wooden floor rapid set to SLC 1550 is ok?\r\nI obviously need a flat surface and to skim the UFH before applying the tiles.\r\n4. Also as the adhesive is very rapid from what I have read, is it ok to mix enough for a few tiles at a time then once these are straight mix some more etc? It also states about how you need to twist the tile. Theres not going to be much twisting with a 2-3mm grout line!

    10th June 2012

    Firstly it is important to ensure the plywood has been screwfixed and is stable and will be free form deflection and also to ensure the undertile heating system is suitable for use on a plywood substrate.

    \r\n

    Then mix and apply the SLC1550 over the heating elements, again check the heating supplier\'s recommendations, but usually a few mm over the wires is sufficient to protect them from the tiling trowel.

    \r\n

    Allow the levelling compund to harden (usually overnight is sufficient) and apply one coat of the Acrylic primer pre-diluted 1:1 with water.

    \r\n

    The tiles should be fitted with a solid bed of adhesive ensuring as close to 100% coverage as possible between adheisve and tile. For best results use a thick bed solid bed trowel and back butter the tiels with a thin skim of adhesive.Do not use dots and dabs. A minimum of 3mm grout joint is recommended.

    \r\n

    I would also recommend, as there is undertile heating, leaving a larger perimeter joint where the tiles meet the wall etc and fill it with a silicone sealant or similar.

    \r\n

    It is ok to mix part bags of adhesive just keep the water ratio the same, approx 2.5L water per 1/2 bag of adhesive (10kg).

  18. I need to apply a lightweight screed to a fiberglass deck thickeness 5 upto 12 mm

    28th May 2010

    Unfortunately we do not manufacture lightweight screeds at this time.

  19. I need to screed an existing garage concrete floor to level (2-3mm) & apply decorative finish(can be resin based but needs to be coloured). Can you recommend a product?

    25th August 2009

    While a standard levelling compound may be suitable, I would recommend the use of Larsen Professional SLC 1500 as the levelling compound. This high quality leveling screed can be applied from next to nothing up to 25mm and will provide a very good finish for the application of decorative finishes.

    In terms of finish we have two suitable products -

    Polyfloor - a medium duty single pack floor paint

    WDC - a two pack epoxy coating offering superior wear resistance

    Both are avaialbel in red, light grey and dark grey as standard.

  20. I want to use SLC 1550 Flex to self level a concrete sub floor approx 65m2, divided into 4 rooms. The maximum depth to be filled is 35mm, with the average depth being around 15mm. I have removed all of the skirting boards and the bottom of the plaster from the walls. As I will be self levelling to the very edge of all walls, should I leave an expansion gap?\r\n\r\nDoes SLC 1550 Flex accept nails (from carpet tacks and wooden flooring)?

    11th September 2017

    Yes we would normally recommend leaving a 5-10mm expansion gap around the perimeter of the room, particularly if the floor has underfloor heating. This can be achieved with an expanded foam joint tape.

    Yes, SLC1550 should be sufficiently strong within a few days to receive carpet tacks etc.

  21. i would like to know if i can mix the flo screed myself by using a water drum & mixer which we use for mixing plaster

    4th January 2012

    In theory yes it could be site mixed in this way. However, in practice it much better to use a pump mixer to ensure a continuous supply of material as the floor is poured. If you would like to talk to someone regarding our Flotherm, call Jonathan Mooney on 07710864634.

  22. I'm being given conflicting advice from tradesmen as to whether self levelling screed is strong enough to be used to smooth out an exposed concrete floor prior to painting. Floors are all internal (ie foot traffic and furniture only). Any advice as to the best type of screed / paint to use would also be appreciated. Thanks

    16th February 2011

    In order to provide a wearing finish a suitable self levelling screed must be used. Our Professional SLC2000 Industrial is suitable for providing a wearing finish without further coating, however the application of a sealer is recommended to reduce the risk of staining. Professional SLC1500 is suitable to receive a suitable floor coating preferably a 2 pack epoxy or equivalent.

  23. Is it possible to use shake top with a 50mm sand/cement screed?

    29th July 2014

    In theory it would be possible, but in practice it may prove very difficult. Shaketop relys on absorbing sufficient moisture from the concrete it is applied to in order to hydrate correctly and also to allow the correct workability to finish and close in the surface. Screed typically contains much less free water than concrete making the whole process more difficult.

    I would advise carrying out a small scale trial to see if it would be practical on a larger scale.

  24. My customer has bought a cement based tile adhesive made by yourselves. He has a gyvlon flow screed floor. Do you supply a epoxy primer to be used inbetween the two ?

    1st December 2009

    When tiling over an anhydrite floor screed, we recommend the following:

    1. The floor should be dry - less than 0.5%. Underfloor heating if present should be tested for 7 days prior to tiling (this will also help to ensure the screed is dry).

    2. Any laitence (scum) should be removed from the surface by brushing or sanding.

    3. The surface should be primed with one coat of Larsen Acrylic primer diluted 1:1 with water followed by one coat of Acrlyic primer applied neat.

    The following is a link to our specification

    Tiling onto gypsum screed

  25. My garage floor was painted some years ago, the paint has lifted in some area and there are patches of white powder showing, I would like to repaint the floor but believe this powder is some sort of efflorescence and the floor will need sealing or coating with a liquid dpm, do you have product that I can apply over the existing floor paint?

    11th August 2014

    By your description it would indeed sound like efflorescence as a result of moisture moving through the floor slab and bringing salts with it. In order to apply a liquid DPM the entire floor would need to be mechanically prepared, removing the existing coating. This can normally be achieved by enclosed shot blasting or grinding the floor. A liquid DPM could then be applied followed by a suitable floor coating.

    Alternatively as a 'quick fix' the paint could be removed in the areas where it has blistered. The exposed concrte could be thoroughly brushed to remove the salts on the surface and washed with dilute acid and the floor repainted. This would not be a permanent solution as the issue with rising salts would be likely to re-occur.

    We do not have a product which could be painted ove the existing painted floor to remedy the problem.

  26. Our builder used screed to cover wet underfloor heating in our new kitchen extension 24 square metres. However,the floor level ended up too low. He has then suggested to use latex self leveling compound to elevate the floor before tiles are laid. Is this something you would recommend? I don\'t want to keep spending more money if this will fail.

    20th October 2014

    It is common to apply a levelling compound to a floor to adjust levels, flatness or smoothness before applying the floor finish.

    Our Latex Levelling Compound is suitble for use over underfloor heating systems.

    If the screed used is calcium sulphate based (which are common with wet underfloor heating systems) it must be dry (<0.5%), suitably prepared and primed prior to applying the levelling compound.

    If the level is to be increased by more than 6mm a different product should be used, perhaps SLC1550 Flex.

    If you require any further information call our Technical Dept on 02890774000

  27. product SLC2500 does it really have to be laid in 5-15 minutes before it sets.\r\nI have an area of 4 sq m to cover it does not seem sufficient time.

    19th April 2015

    The working time of 5-15minutes is more related to after the product has been poured onto the floor. When mixed the product remains usable for around 40 minutes. After pouring on the floor, any moving or spike rolling etc should be completed within 15 minutes to ensure the best finish.

    Hopefully this helps.

  28. The builders had just left my house after laying a 25m2 concrete screed \r\nthen the dog escaped we now have a patio which is a mess . Covered in holes paw prints scrapes etc these range from 25mm deep prints to 3mm scratches. I would like a outside product that I could floot across the patio that would fill the holes and make everything in my world ok again\r\nmy biggest problem is the patio runs away towards a drain \r\nmany thanks\r\nSterling groves

    23rd September 2015

    There are a few of options.

    We have a patch repair product called Rapid Patch which could be used to skim over the paw prints etc. While this is close in colour to concrete the repairs may still be visible.

    Another option is SLC2500 which is a external levelling compound. With care this could be mixed slightly stiff to allow for the falls.

    Finally, a thin section (10-15mm) polymer modified screed could be applied incorporating Larsen SBR Bond. This would be trowel applied like a traditional semi-dry screed.

    If you would like to discuss further contact our Technical Sales on 07710864631. 

  29. we are carrying out fast track office fit-out and need to infill floor void at first floor level where stair has been removed. we are installing t-beams with insulation over and 75mm concrete screed to take carpet finish. we need floor dry as quickly as possible. what product would you recommend to reduce drying time.

    18th November 2009

    Instead of 75mm concrete screed, use Larsen dry4 screed, this is a proprietary hydraulic, rapid drying screed. It can be covered after 1 week.

    Alternatively, after placement concrete apply Larcote DPM (2-part epoxy dpm) onto concrete and SLC 1500 @ approx. 5mm.

     

  30. we have poured a calcium sulphate screed 15mm to low is there a poduct which we can over pour to a depth of 15-20mm

    10th November 2015

    There are calcium sulphate based levellers available on the market but we do not supply them. 

    It is possible to level a calcium sulphate screed at 15-20mm using Larsen SLC1500 or Larsen SLC1550.

    The following preparation must be carried out:

    1. The heating system (if present) must have been tested up to full running temperature.
    2. The surface of the screed must have been mechanically prepared, for example by grinding and vacuuming.
    3. The screed must be dry, i.e. below 0.5%CM as tested with a Carbide (Speedy) moisture meter with the sample chiselled out to 40% of the overall screed depth.
    4. The surface must be primed with 1 coat of Larsen Acrylic primer diluted 1:1 with clean water, followed by 1 coat applied neat. The primer must be allowed to dry.

  31. We have removed the existing Marmoleum Floor Covering over six flights of concrete stairs - the thread surface remaining has adhesive that is very difficult to remove without further damaging the concrete surface. We are proposing to lay a carpet on the stairs. Would you recommend the Larsen Latex Self-levelling compound as an overlay on the old glue/concrete surface as a preparation for the carpet?We note that some of your products can be laid on old adhesive.

    4th August 2015

    Normally we would recommend that 75% of adhesive residues are removed and anyhting remaining must be firm, stable and not water softenable.

  32. we want to use standard floor screed mix of sharp sand and cement with fibres for garage screed but understand that we should take added measure for strength and surface wear. whats recommended.

    25th March 2014

    Adding Larsen SBR Bond to the mix will improve the abrasion resistance of the screed. Alternatively applying a sealer or paint coating may be sufficient in a domestice garage.

  33. What product do I seal concrete with to allow me to tile after 3 days curing

    7th April 2010

    Current recommendations and best practice suggest concrete should be 6 weeks old before tiling. This allows the concrete to have gained a suitable level of strength and dryness and ensures that the majority of any early age shrinkage and associated cracking has taken place before tiling.

    The main risk from tiling too early is that drying shrinkage cracking may occur in the concrete leading to cracking or debonding in the tiling installation.

    If you are forced to tile onto concrete this early we would recommend using a decoupling matting system, such as our Seri-Dec. These systems help prevent stresses from the substrate being transmitted into the floor finish.

    For further information consult our new tiling brochure or phone for further technical advice.

  34. Your "Dry 4 Screed" has been specified to construct a 6m x 6m x 100mm base on an existing concrete floor. Can you tell me what quantity of your product I need to order. Also what proportion of water to SBR Bond (Larcem 25) you recommend. Should I use a Mix of Larcem 25 and cement as a bonding agent to the existing floor and new base

    9th November 2009

    This would require approximately 275 x 25kg bags of Dry 4 Screed.

    Larcem 25 is usually diluted 1 part with 3 parts water to be used as a gauging liquid or mixed 1:1 with cement when used as a bonding agent for bonded screeds.

07 Renders and Plastering

  1. best method of applying render to concrete lintels above widows and best mix

    12th September 2009

    Ensure the concrete is free from dust, mould oil or any other contaminants. Apply a bonding grout of Larcem 25 mixed 1:1 with cement and then immediatley plaster with Mix A as described on the Larcem 25 datasheet.

  2. Can 25 SBR bond priming slurry be applied with a textured roller and allowed to harden before rendering like Larcem 55

    17th October 2014

    Yes an SBR Bond bonding slurry can be applied in this way.

  3. Can I apply new rendering directly on top of an existing small pebble dash which is in good condition or must I remove it first?

    2nd May 2011

    It is always best practice to remove old renders, especially when they are pebble dashed. Otherwise there is a risk that the original render will not be sufficiently strong to support the weight of the additional layer of new render.

  4. Can I use Diamond (Structo-Lite) for verticle brick stamping?

    10th October 2017

    Diamond (Structo-Lite) is not one of our products. I suggest you contact Usg - www.usg.com directly.

  5. Do you have a product that will allow me to render directly onto a concrete blockwork retaining wall. The retaining wall is external... my concern is potential spalling of the render in the future

    11th March 2011

    Larcem 25 SBR Bond can be mixed with cement to provide a priming slurry. This should be applied immediately before the scratch coat with the scratch coat applied wet on wet. This will ensure a very strong bond of the scratch coat to the substrate. Further, Larcem 25 SBR Bond can be mixed with the render to improve bond, flexibility and ultimately crack resistance.

  6. Do you have a solution for waterproofing a painted roughcast dash render on a solid house external wall.

    12th February 2010

    Unfortunately no. Larsen Water Repel and Larpuf SWR are both surface applied masonry water repllents, however both products must be applied to a porous surface in order to function.

    This leaves you with two options, either remove the paint and apply a masonry water repellent or alternatively simply repaint the wall with a suitable water repllent masonry paint.

  7. Do you market/recommend a suitable sealer product which would prevent a soot staining problem penetrating through a plaster skim finish on an interior wall of Church Building

    12th May 2009

    Unofrtunately, I do not think our sealer would be suitable for this application. However there are specialist paints on the market which can prevent damp and staining showing through the top coat paint.

  8. House, 14 years old with red algea staining on external wet dash roughcast render. Do you have a product that can remove this without seriously damaging the render

    23rd June 2009

    Larsen Concentrated Algicide will deal with most algae staining. Simply dilute the product as directed and spray onto the affected area and allow to dry.

    In heavily contaminated areas the area should be powerhosed to remove heavy deposits and then sprayed with the diluted algicide as above.

  9. I have moved into a new build which is externally finished I krend, the south facing wall suffers from penetrating damp in wind driven rain. have you a product that can be applied to k-rend ft, which is supposed to contain silicon to repel water,in order to help prevent water penetrating from the outside.

    6th December 2015

    We have a product (Storm Repel) which is deeply penetrating wate repellent cream applied by roller in one coat.

    This should achieve the deisred result.

  10. I have to plaster an old block wall that is 20 years old and is covered in red algae on both sides.Is there a product that will guarentee to get rid of the algae and the plaster not to blow off.

    17th July 2010

    Larsen Concentrated Algicide can be used to treat algal growth prior to plastering. For best results remove as much groth as possible by power washing etc, then apply Larsen Concentrated Algicide as directed.

    Larsen Concetrated Algicide will have no effect on subsequent plaster or paint coatings.

  11. I need to render a Victorian brick tank to make it water proof. The current render needs replacing. Can you reccommend an additive or a render and if neccessary a surface treatment.

    The water stored is rain water and is there any way to do this for the water to be safe for human consumption?

    16th March 2010

    Unfortuantely if this is for drinking water we do not have a suitable product. The render or additive in this case would need WRAS approval.

    If the water is not for consumption then there are a number of tanking options available including Larsen Integral Waterproofer, Larpruf CG and Larecm 25 SBR Bond. Contact our Technical Sales (a.duffy@larsenbuildingproducts.com) for further advice.

  12. looking for a product to clean red algae off white dashed wall

    28th April 2014

    Larsen Concentrated Algicide is suitable for the removal of red algae.

    Technical Datasheet

  13. seeking advice on how to prevent cracking in a narrow band of external render applied to metal lath fixed to timber beam, dimensions 0.3m deep by 3.5m long? i'm thinking expansion joints, glass fibre mesh and polymer additive.

    20th October 2010

    Your idea is correct, add Larcem 25 SBRBond to the render mix (dilute 3:1 with clean water and use this as the gauging liquid). The inclusion of reinforcing mesh and a separation joint will further reduce the risk of cracking.

  14. the soft stone surrounding a bay window in a 1900 house has cracked in places and the surface come away, I need to rebuild the original profile with render and then paint. do you have a product to apply before commencing the rendering or to mix with it/ the surface of the stone is very soft.

    21st March 2010

    If the stone is very soft, the best option would be to remove it and replace with a similar material this would probably also mean bedding in with a Hydraulic Lime Mortar.

    If the damage to the stone is not siginificant the profile could be raised with the application of Larsen Rapid Patch fast setting repair mortar.

  15. What is the best product to apply to a dry dash render after it has been applied to prevent water ingress and maintain it colour?\r\nRegards,

    8th June 2014

    We have a few products which can be surface applied to cement based renders, including dry dash, which will greatly reduce the water permeability and therefore water ingress as a result of driving rain. These include Water Repel, Repel 38 and Repel N. 

    For further information contact our Trade Counter on 02890535446.

08 Others

  1. A contractor has used Larsen Wood Preservative to treat timbers in a house and has splashed and smeared it on the plastered walls of the rooms (green colour). Can you recommend a product to block the stains and stop them coming through freshly applied paint?

    4th May 2011

    The first thing to do is to ensure the Wood Preservative has dried, as it is solvent based, any residual solvent could affect the bond of the paint. Once it has dried any commercially available stain blocking paint (such as products available to block nicotine stains) should be sufficient to block the colour. The dyes used are solvent soluble not water soluble and so should not migrate through a water based paint.

  2. Can I use feather edge to repair a floor with underfloorheating

    4th February 2010

    Yes, Larsen Featheredge is suitable for use on a cement based floor (concrete or screed) with underfloor heating. It is not suitable for repairing gypsum screeds.

    Ensure the heating is turned off 48 hours before application and allow 24-48hours before switching the heating on.

  3. Can the Polyfloor Garage Floor Paint be used on a gypsum based (calcium suplphate) floor screed? If so, are there any special precautions that need to be taken? e.g. when tiling where the floor had to be double primed?

    22nd September 2011

    Polyfloor would probably be okay for use on a gypsum screed, but it would be better to use a water-based epoxy coating like our Larcote WDC. Water based epoxy coating tend to exhibit a better bond to gypsum screeds than solvent based coatings.

    Normal paint preparation methods are all that is required, if the surface has laitence, then it would be recommended to grind/buff the surface and vacuum before coating. The first coat of WDC can be diluted with up to 10%water for use as a priming coat. The screed shoud be dry prior to coating.

  4. Can you provide a product sealer to apply on to a bradstone masonary block wall to form a seal againest water ingress

    5th November 2009

    Larsen Water Repel can be applied to most absorbent surfaces such brick, render or in this case Bradstone block and will provide a water repellent seal against driving rain.

    Water Repel must be applied to a dry surface in dry conditions.

    An alternative is Larpruf SWR which is a water based silicone type water repellent.

  5. Do you have a product which would safely remove Bitumen from soft red brick please?

    1st December 2009

    Remove as much as possible by scraping or other mechanical means. the remainder can then be softened or dissolved by the application of white spirits or simiar solvents and blot off with clean cloth.

    It will be difficult to remove the bitumen completely from the brick and there is a risk that the solvent may carry the stain deeper into the brick so carry out a small trial first.

  6. Do you have a suitable product to repair damaged wood such as thixopropic 2-pack epoxy

    1st February 2012

    While we don't have a specific wood filler, we have a couple of products which might do the job - Larcrete PM Polyester Mortar and Larfix E Epoxy Adhesive and Filler.

  7. Do you have a surface sealer and curing membrane product for application to green concrete?

    21st October 2015

    Larsen Acrylic Concrete Sealer (previously Acraseal) is suitable for this application. 

  8. Do you produce an accelerant for gypsum based products, we particularly need to accelerate board adhesive and bonding coats?

    8th September 2015

    Unfortunately we do not. Further adding an external additive to a preformualted product could leave you open should anything go wrong. I woudl suggest the best option is to talk to the manufacturer of the gypsum products. 

  9. Do you still have repel 38 or what other waterproofer product for outside brick & plaster surfaces to seal them

    27th July 2015

    Yes we still carry this product but have recently rebranded it as Stain Repel.

    Also in the range is Storm Repel (previously Repel N) which is a creamy one-coat water repellent whihc is deep penetrating and easier to apply on vertical surfaces by brush or roller.

  10. Fire cement. I understand that this product comprises of sodium silicate but is it a silicone based product? Is sodium silicate a form of silicone? Thank you

    21st October 2014

    No our Fire Cement Sealant is not a silicone based product.

    It is as you say based on sodium silicate which dries and hardens to a glassy type material rather than a rubbery material like silicone.

  11. Have sprayed joists, u-sides boards of a bedroom floor 4mx5m using your clear wood preservative. How get rid of smell?

    22nd March 2016

    Unfortunately our Wood Preservative is solvent based and when used internally the odour can linger.

    The only thing which can be done is to increase the ventialtion to the treated timber.

    The directions on the tin clearly state that internal use should only be carried out with care as the solvent odours have a tendency to linger.

  12. Hello at Larsen\r\nWe have a \"temporary\" situation which could last a couple of years. The house floors have the screed finish only on them. We have to install a log burner stove for temporary heating. I would like to just seal the area around the stove so it could act as a hearth and not get stained with ash and black deposits from the stove. I would like to be able to clean the sealed area with damp cloth, and not let the stove dirt penetrate the screed. Can you recommend a product for this job please?

    24th March 2014

    We have a number of sealers which would be suitable. In this instance the key will be to apply a sufficient number of coats to create a fully sealed surface. this will depend on how porous the screed is, but typically 2-3 coats should be sufficient.

    Larsen Acraseal or Path and Patio Sealer would be recomnmended.

  13. Hi I am looking a polished concrete sealer that will leave a high sheen on the surface when dried its for worktops etc.

    29th January 2017

    With polished concrete it is often best to achieve the sheen/gloss through polishing alone. A gloss sealer will often wear and mark more quickly than the concrete. 

    Successive polishing up to 3000 grit will usually be sufficient to achieve a high gloss finish. This can be protected with an impregnating sealer such as Larsen Stain Repel which offers protection against oil and water based staining. Best results are achieved by applying before final polish or simply buffing the surface once sealer has dried. Stain Repel will not affect the appearance of the finished surface.

    A wax based polish can be used on the finished surface to improve gloss but it must be borne in mind that this will require maintenance throughout use and reapplication, probably every year.

    Personally I think the application of Stain Repel to protect the finished concrete is sufficient. As this will allow the concrete to build up its natural patina with use but still protect it from more severe staining.

  14. Hi I\'ve used your impregnator sealer on my slate tile patio and didn\'t realise you had to make sure you get the excess of. It has now left the slate with white blotches all over it what can I do to rectify it please?

    12th August 2014

    Cleaing the affected area with white spirits or similar is sometimes suffeicent.

    If that does not work hot water pressure washing is usually successful.

  15. Hi, I have a query about Larsens Wood Preservative and The petrol like fumes it gives off. If there is a room that the fumes seem to collect in regardless of ventilation, what would your advice be? Can those fumes cause any kind of irritation or harm? And is it ok to sleep through the night in a room where the fumes are concentrated? What would the advice be if it were a child\'s bedroom?

    16th September 2015

    The solvent used in Larsen Wood Preservative is similar to home heating oil.

    It is recommeded to use internally with care as the solvent odour can linger.

    Usually in a well ventilated area the odours will dissipate within a few days.

    I would recommend to continue to ventilate the area until the odour has gone, in cases of widespread use or spillages it may be necessary to use mechanical ventilation before re-occupying the room.

  16. Hi, I'm about to build a timberframe house with a basement area within shuttered retaining walls, the specification includes a membrane on the inside of the walls (Newton 500) but nothing on the outside. Some of the formwork contracters I have spoken to say there should be a coating or membrane applied, one has suggested a paint on black bitumous coating which they use on bridges, I have looked at your website and find a simple bitumen paint but also Larcote PE. Even if not required I would like to ake a belt and braces approach and apply something to the outside before the backfill - what do you suggest/recommend ?

    8th June 2010

    Generally, when a membrane/drainage system is specified, there is no requirement for another waterproofing system. It may be worth talking to the membrane manufacturer at www.newton-membranes.co.uk.

    Larsen Black Bitumen Paint will offer a degree of protection from water ingress, but like any paint coating it may get damaged during backfilling. Another option would be to apply Larpruf CG to the external wall. This is a cement based waterproofing slurry which would greatly reduce the passage of water throught the wall.

    The most important factor would be to ensure that the walls are constructed using best concrete prcatice and that great care is taken over details and to eliminate the risk of cracking.

  17. how long between coats on lardec wood stain

    11th October 2013

    The second coat can be applied after the first coat has soaked in and the surface is touch dry which is usually within 2 hours.

  18. I am linking an old concrete foundation to a new one with rebars by drilling the old and inserting the bars. Would any of your epoxy products be suitable for fillings the holes to satisfactorly anchor the rebars in the old foundation?

    23rd March 2009

    Our product Larfix E Epoxy Adhesive is routinely used for similar applications. After drilling the holes, they should be blown out with an airline to ensure they are dust free. The hole should then be partially filled with Larfix E mixed as directed and the rebar pushed in with a twisting action to ensure full contact and absence of voids. REmove the excess Larfix E from the mouth of the whole before set.

  19. I have a couple of patches of either fire cement or high tempararture mastic on a riven slate hearth. Can you please advise the best way or product to remove this without damaging the slate.

    31st July 2014

    Unfortunately cured fire cement are quite 'glassy' in nature and as a reuslt are very resistant to both chemicals and temperature. It is likely that mechnical means are the only way to remove these residues.

  20. I have a fence which has been treated annually for the past 5 years with larsen wood preservative. Would it be suitable to prime this with lardec with out treating again?

    30th May 2012

    There is no issue applying Lardec to timber which has previously been treated with our wood preservatives so long as the solvent form the wood preservative has fully dried out. Always carry out a trial in an inconspicuous area first to ensure you are happy with the results.

  21. I have a large timber barn which is in good condition. The site is reasonably exposed, particularly the southwest side where the prevailing winds come from.......I need to decide which product to use i.e. Lardec, Lardec 24 or Creocoat. Can you advise the difference between Lardec and Lardec 24? How many coats would you recommend? Do you recommend an annual maintenance coat?

    13th November 2009

    Depending on the type of timber and exposure conditions it may be advisable to first treat the timber with 2 coats of Larsen Clear Wood Preservative.

    Once this has dried the wood can then be stained as required. Lardec 24 has higher resin solids than Lardec (and is therefore more durable) and this would normally be applied in two coats in exposed conditions. Maintenance coats can then be applied as required and this will greatly depend on the exposure conditions but would typically be every two years.

  22. I have an old blacksmiths in France that i am restoring. It has stone walls inside with lime based mortar. I want to keep the masonry exposed and just want to clear coat it to stop it gritting and making dust when you rub against it. Do you have a suitable product which is also breathable.

    23rd May 2012

    We have a few sealers which will bind the surface and will keep the dust down, in particular Acraseal and Path & Patio sealer. They will also darken the surface slightly which can help the aesthetics, however, we cannot guarantee the \'breathability\' of these products. In theory a single thin application should remain breathable, however, more coats or thicker applications will correspondingly reduce breathability.

  23. I have just applied 1 coat pva bond 1 to 5 mix on to my garage floor, which was done and painted 3 years ago but was lifting in high traffic areas do i put more coats on and do i paint it when tackey

    24th August 2012

    PVA Bond is usually only used as a primer for painting emulsion over gloss paint. Garage floor paints were traditionally solvent based and in this case PVA Bond would not be a suitable primer.

    I suggest contacting the paint supplier you propose to use and getting their advice.

    If they suggest removal of the PVA, this should be easy to do by scrubbing with warm water.

  24. I have used your sealer to seal my slate floor outside.\r\nThe supplier gave me 4 tins to cover 44sq mts. If I do 2 coats, how long should I leave the first coat.

    28th May 2012

    Depending on the product as soon as the first coat has dried or absorbed into the surface.

    With Impregnating sealers this can normally be carried out after around 30min.

    With surface sealers such as Acraseal it may take 1-2 hours.

    Drying times are dependent on site conditions and the porosity of the substrate.

  25. I have window cills, 35 years old, which have been pained over the years with santex, oil based paint and latterly with exterior masonary paint. Those exposed to the sun all day flake over time. Exterior paint gathers soot spots and is difficult to keep clean. I am currently cleaning them down to concrete which still has a smooth sutface and only one of 13 has some slight spalling. can you recomment a total treatment which will be durable in sunlight, smooth for cleaning and white. Someone suggested floor paint. Would this do?

    24th August 2011

    I would recommend you talk to a paint manufacturer for advice on the choice of paint. I do not think floor paint would be suitable.

    As with most things the key is in the preparation. It would be advisable to ensure that they are stripped back to bare concrete, if using a chemical paint stripper, ensure they are also well washed to remove any residues. Remove any loose or friable material and dust.

    Using a suitable repair mortar (e.g. our Feather Edge) re-face the surface to leave it uniformly level and smooth.

    Depending on the paint used a water repellent primer or priming coat of paint would be recommended.

  26. I purchased 5L containers of algicide last in October 2013. It has been stored in warm, dry, dark area. If used to spray render in April/May 2015 will it still be effective or does it degrade?

    8th February 2015

    Unfortunately, as the material is outside our recommended shelf-life we cannot guarantee performance.

    That being said, if the storage conditions are good and the material is in unopened manufacturer's container and there are no obvious signs of deterioration then there is a good chance the material is still usable. I would recommend carrying out a small trial area in an incospicuous area to test the product.

  27. I want to use a Larsen Easy Foam as feeler to my roof wooden construction between placed the joists and Roof Insulation Board. \r\nI want to now something about Larsen Easy Foam structure.\r\nIs Larsen Easy foam has closed or opened cell structure?

    8th December 2014

    Larsen Easy Foam is closed cell when cured.

  28. I wish to use your woodworm treatment solution. I want to know what type of respirator to use as i will be applying by spraying - I have a full face respirator I just want to know what the correct type of filter to use with your product as I will be applying in an enclosed area.

    20th August 2011

    An organic vapour filter should be suitable. It would be advisable to inform the supplier of the filter of the product details to ensure the correct grade is supplied.

    We would always recommend trying to ensure there is also sufficient local ventilation / extraction when working in enclosed areas. If this is not possible an air fed respirator would be advisable and also to always carry out a risk assessment.

  29. i'm looking for a jointing sand stabilizer in your product range?

    24th October 2008

    We have a specific product for this application - Larsen JointSave. This is a water-based polymer latex which will soak into the jointing sand and bind it together.

    Alternatively application of Larsen Polyseal will bind the jointing sand and seal the paving to enhance and protect.

  30. I'm looking to purchase a fire retardent expanding foam to seal openings in walls where cables and pipework have been installed. I need a fire retardent foam but I want to make sure we purchase a suitable product. This is for use throughout the site but also in a boilerhouse and electrical switchgear room. Can you recommend a suitable product that meets any applicable Building or Fire Regs. Thanks.

    21st July 2010

    Larsen Fire Retardant Expanding foam is a one component polyurethane foam which is designed to make a fire retardant seal between ‘stony’ construction parts.

    It is used to produce a high quality rigid polyurethane foam which bonds, seals and insulates most construction materials offering a fire rating of up to 80 minutes. The cured foam is resistant to most chemicals.

  31. Larsen Water repel has been recommended for one of the external walls on my mothers house. There is Virginia Creeper on most of the wall. The installer is going to remove the creeper before applying Water Repel. Will the product be effected by the creeper growing back over the wall in time?

    17th June 2010

    Larsen Water Repel once dry should not damage the Virginia Creeper. However, it will render the facade water repellent and as such the wall may be less suitable to sustain the growth of the plant.

  32. Larsen Water Repel has been used on my house to prevent ingress on rain water into the brick work. The application was done in windy weather and there is still some water coming through.
    Should Larsen Water Repel be used for this type of application?
    Can Larsen Water Repel be applied by brush rather than spray?
    Can Larsen Water Repel be cleaned from glass windows and also self cleaning glass?

    14th December 2009

    Larsen Water Repel is a surface applied masonry water repellent designed to reduce the penentration of driving rain through brick, block, render or stonework. Depending on the porosity of the masonry, 2 or more applications may be required to ensure adequate protection.

    Larsen Water Repel can be applied by spray or brush to dry surfaces. When applying, best practice should always be followed and this would mean not applying by spray during windy conditions due to the risk of overspray.

    Overspray etc of Larsen Water Repel is difficult to remove from glass and other surfaces and this should always be avoided.

  33. My parents used Larsen Wood Preservative to treat attic woodworm 2 weeks ago. The smell is still really strong, and tends to move around the house depending on time day and heat etc in a bungalow. They have practically left all the windows open for 2 weeks now, but the smell still is quite strong at times, and not there at other times. Any advice appreciated.

    6th May 2012

    Our Wood Preservative is a solvent based product and so must be used internally with care. It is important that adequate ventilation of the area exists during application and until the solvent odours dissipate. The smell of the solvent can linger for a considerable time if significant amounts of wood preservative are used and in these cases forced, mechanical ventilation methods may be required.

    It is also possible that the \'smell\' is resulting from a very low level of residual solvent and is just \'clinging\' to furniture etc, much in the way a small spillage of heating oil can linger.

    In order to be safe I would recommend trying to ensure an adequate airflow through the property and in particular, through the attic.

  34. Plaese advise on how to remove residue from cured easy foam (expanding filler and sealer) on foil coated pvc windows.

    6th March 2011

    Cured expanding foam should be mechanically removed, i.e. carefully scraped off. Small amounts of residue may be softened and srubbed off with alcohol or similar. Always check to ensure the solvent used (alcohol) doesn't damage the substrate (the frame).

  35. Please confirm the maximum bed thickness of Streetscape FBC for laying 65mm yorkstone paving is 75mm/ as per technical data sheet\r\nThank you\r\nGrant Jackson

    7th April 2017

    FBC can be laid up to 75mm in a single pass.

    Thicker beds are also possible.

    For thicker depths I would recommend laying in layers of 50mm wet on wet compacting each layer in turn. The final layer can then be compacted with the bedding of the stone.

  36. Ref control of dry rot\r\nCan Larsen protim be applied through a non thermal fogger to apply forenstance under a stairs to make contact with hard to reach areas.\r\nThank you

    26th September 2017

    Larsen Protim 265 wood preservative is only authrosed for application by brush, spray or immersion. It cannot therefore be used with a fogger.

    For best results in hard to reach areas, application by spray (talking the necessary safety precautions) would be recommended.

  37. We are re-developing a site at Amersham (Buckinghamshire) and the existing 55mm sacrificial concrete floor screed has been lifted to expose the structural concrete floor deck.\r\n\r\nIt is intended to replace the old concrete floor deck with a ‘wet’ underfloor heating system consisting of insulation mat, pipework and T&G OSB flooring like for like depth at approximately 55mm\r\n\r\nThe concrete floor deck is uneven and to establish a uniform level finish we have variations of between 2mm and 12mm to fill as a continuous screed.\r\n\r\nThere is approximately 1467M2 of area to cover so our preferred method would be to pump and self-level for speed\r\n\r\nYour assistance to select the most fit for purpose product would be most appreciated

    24th June 2016

    Larsen Professional SLC1500 would be the best product for this application. The concrete slab should be cleaned and free from dust or other contamination before applying Larsen Acrylic Primer - first coat diluted 1:1 with water, second coat neat and allowed to dry clear. SLC1500 can then be applied from feather edge up to 25mm and can be pump applied. 

  38. We have a contractor who has used Larsen Wood Preservative to treat existing roof timbers. He has only applied one coat and your instructions asks for two coats. He has applied a very liberal coating and by our calculations he has achieved the same loading. Is this okay?

    21st December 2010

    The important point is to ensure a suitable concentration of active ingredient is achieved within the timber. This can be achieved by painting, spraying or dipping. The application methods for our product are based on recommendations for this type of product as detailed by the HSE.

  39. We use alot of timber to manufacture various crates/crating systems. We are looking into a sealant/preserver in case customers leave timber (or ply) crates outside in all conditions. Would you have any ideas?

    26th June 2008

    Larsen Wood Preservative (Clear) can be used 'industrially' for the preservation of timber. The easiest method would be to spray (2 coats) or ideally dip the timber (~1 hour) to be treated. The timber to be treated should be as dry as possible to allow penetration of the preservative. Always test a trial area first. Please be aware that this product is solvent based and so adequate health and safety precautions should be taken as required. I would advise carrying out extensive trials with any plywood as the solvent may affect the glue binding the layers of ply.

  40. What product can be applied to rendered external walls disfigured by rain water running off concrete coping stones

    5th November 2011

    This is normally a result of dirt carried in the water penetrating the surface of the render during rain. Often the best way to prevent the problem is to ensure all drip grooves and related detailing is such to prevent water running off the coping or sill directly onto the render.

    Where this cannot be prevented or where the problem still exists, the application of a stain resistant impregnation treatment such as Larsen REPEL 38, can greatly reduce re-occurance. Furhter, after the application of REPEL 38 to a surface both water and oil based staining will be much easier to remove as well as being less prevalent in the first place.

  41. What superplasticizers will you advise ready mix concrete suppliers for long distance deliveries (180 minutes) under 33-36 degree celcius climate temperature

    27th December 2014

    I would recommend carrying out trials before attempting this using two admixtures - Chemcrete R610 (set retarder) and Chemcrete 100Plus (Superplasticer). Once suitable dosages are determined, a single component blend could be supplied for this job.

  42. WHAT TYPE OF RESPIRATORY PROTECTIVE MASK DO I NEED WHEN SPRAYING ON LARSEN WOOD PRESERVATIVE IN A CONFINED SPACE

    4th March 2013

    You should take advice from the mask supplier. It is likely that a mask suitable for spraying solvent borne paints will be suitable.

    It is also important to note that great care must be taken when using our wood preservative indoors or in confined spaces as the solvents contained are slow to dry and are likely to linger in areas with restricted ventilation.

  43. What typer of sealer would you recommend for sealing concrete roof tiles, some type of sealer that i can spray on

    20th April 2009

    We do not have a specific product for application onto in situ roof tiles. There are products available on the market which provide a full weather proof, rubberised coating of tiles and slates in situ and companies which carry out the supply and fit.

    If you only require to seal the surface to reduce moss growth etc, then the application of Larsen Path and Patio Sealer should be sufficient.

  44. when is the best time to spray algicide onto tarmac

    21st March 2017

    Ideally, it should be sprayed on a dry day with no rain forecast for the next 24 hours or so.

  45. While installing cables in refurbish house I notice some wood worm. Is it ok to spray your product as cables and pipes are installed. I have already used some .

    8th November 2015

    Larsen Woodworm Killer is solvent based and the solvent may damage plastics. It is also flammable, so care must be taken that there is no risk of sparks etc. When used internally the solvent odour may remain for some time.

  46. within the last 3 weeks i have painted creocoat on both sides of builders planks and then made them into seed boxes which i have filled with soil. will the crecoat affect the tree seeds from growing, kill the seeds or will they be ok ?

    21st May 2012

    I would not recommend using Creocoat to stain timbers used to make seed boxes or the like as there is a risk that some of the lower volatility oils in the Creocaot may leach out over time and damage the plants.