Traditional screeds. If under the screed this is normally a polythene dpm so the screed is then an unbonded screed, whereas if the dpm is on top of the screed an epoxy-type dpm is used. British Standard (8204:1) says minimum 65mm for domestic floating. Don't use a bitumen at all, you are correct eventually your screed will fail. 10 Sep 2021. Consideration should be given to applying the DPM to the top of the slab, as the installation and moisture sensitive internal finishes are then protected from any residual moisture in the concrete. . When applied on top of screed, it needs to have a further coating to protect it from damage such as laminate, tiles, vinyl, wood and carpets. Liquid DPM for Walls. It is essential that this. CSC screeding was very efficient that they screeded our floor in under 4 hours (around 91sqm) with the help of the Mixamate. The subfloor in my house is a concrete slab with no DPM. O and the Answer to Mapei and Uzin is no. Under Floor Heating; Screed Care; Testing; Tips; Blog; Contact; A Practical Guide to Screed Testing: What Do the Experts Say? Download. My question is thoughts on floor layout. We have our own in-house delivery fleet of FORS Gold vehicles with Moffett mechanical off-loads delivering nationwide. Consideration should be given to applying the DPM to the top of the slab, as the installation and moisture sensitive internal finishes are then protected from any residual moisture in the concrete. 67. indd 2 08/08/2016 16:50:21DPM underneath and a plastic sheet on top to stop the screed getting between the insulation panels. +44 (0) 333 202 6800. We have a few options: 1. Use a thick bed adhesive unless your competent to use screed, it takes skill and practice to create a flat floor. Hello, hoping someone can help. 28. Mark El-Kadhi New Member. The liquid membrane forms a strong seal and makes a permeable layer to enable moisture to evaporate off. DPM over a new underfloor heated screed, the heating system must be turned off 48 hours before application. hallbeck New Member. Location. I. ARDEX DPM 1 C may be used if; 1. This allows for the full 5kg or just half to be mixed at once depending on the area to be covered. Unfortunately soon after it was laid it started crumbling and holes were appearing in places, as electricians and plasters came in to do their work and walked all over it, they did put black sns plastic sheeting down to protect it though. Top. 6 March 2017 at 8:04PM edited 6 March 2017 at 8:59PM. Vac up any loose sand once it's set and then tile. 29 per m², £42. He also saw hairline cracks in the top layer of screed in places. JB Flooring Well-Known Member. Customer asked me how did they stop rising damp before the Dpm sheet was used and it made me think ( that hurt ) . This was due to a neighbour redirecting the water from his gutters. No this is designed to be used under floor screeds, tiles, render or plaster. VCLs prevent excess moisture entering a wall’s cavity, behind the insulation. If its not right. hot bitumen, or cold bitumen in solution. Screed & Insulation. The DPM should: have sealed laps of at least 300mm wide link with wall DPCs to form an impervious barrier to. Through DPM of course so a bit of silicone down the screw hole to seal the hole. £14 per m2. Brian shows how to correctly fit a Damp Proof Membrain - DPM in a new build houseLink to the T-Rex tape Website Http://bodgeitwithbri. will come down and meet the insulation under the screed so the screed is totally floating. 5sqm has blown. The builder wants to apply a DPM to the top of the slab before it is dry. DPM’s can be applied to either a suitable blinding layer under the slab or internally to the top of the slab. The DPM we use does not cancel all moisture out as this will end up. Modified anhydrite screeds for use with UFH can now be installed as little as 35 mm deep with a 15 mm pipe in a domestic application. The tiler can then latex or screed over the DPM. 0113 2455450 sales@rawlinspaints. 5kg multi chamber bags. Fig. Alan Jackson - Commercial Manager UK and Ireland - Gypsol. Thanks for the reply. 27 Dec 2020. £12 - £16 per m2. Looking for best method to both level and damp proof the concrete, to then be covered with a thin layer of celotex, then engineered wood or laminate. Visqueen 2000 gauge Polythene - 12. Care must be taken to a) ensure there are no holes or tears in the sheet that could allow. framing joints secured with not less than 2 nails per joint. No need for double DPM. Mark El-Kadhi New Member. 21m2 1. Tramex reading at the time of vinyl removal was 3-4+. Hi, I have an area of approx 6m by 3m on a ground floor extension which is block and beam construction, that I now need to insulate and screed to finished floor height. 4 Screed. As a rough guide, laying a conventional sand/cement screed costs around £15/m2, increasing by around £5/m2 when delivered ready-mixed. Prime and reapply , then screed to level and tile. In terms of where the insulation should be placed, it can either be placed under the slab or between the. The tiler can then latex or screed over the DPM. Will prim t be okay as primer on top of turbo? Thanks PeteUnless designed otherwise, the minimum specification for all partitions should be: sill and head plates 63mm x 38mm. The purpose of DPM. Greater thickness of screed may lead to a colder floor. I recently had a new boiler installed and new radiators fitted, and the plumber has cut the old copper. The screed manufacturer agrees that their screed can receive an epoxy DPM. 3k. Fibreglass 1. As you would expect, you need as much heat as possible to flow upwards and into the room. Maximum depths are around 10-15mm, however with the addition of bulking aggregates (normally kiln. The bitumen is about 20 mm thick and, I believe, serves as moisture barrier as well as an 'appearance' finish. Had a look at the pics and IMO no dpm under the subfloor. . Insulation must be provided under their entire area to ensure compliance with the Building Regulations is achieved. enquiries@visqueen. Preparation is key with these coatings and the substrate must be sufficiently clean and dry. Screeds are covered by BS 8204, Screeds, bases and in-situ floorings, (2004). Use 1000 gauge or thicker – ideal for this is the polyethylene use for the DPM under your concrete subfloor. We are in the process of having an extension built. Norfolk. 65mm Screed. A Damp Proof Membrane or DPM is a waterproof barrier that’s introduced between your sub floor and your wood floor. F. If there is an operational DPM beneath the concrete you don't need one on top. A poorly compacted, damaged or weak screed should be completely removed by mechanical means and reinstalled correctly. screed (with UFH) 75mm. . #5. Then a DPM on top to avoid them floating in the screed. Screed above dpm. Country. They can therefore be laid under the DPM (the DPM is still necessary to prevent. – the UK’s leading manufacturer of flooring adhesives and floor preparation products for the contract flooring industry. Try it free. Answered 22nd Aug 2016. hot bitumen, or cold bitumen in solution. However the chance that the floor tiles or adhesive can release fibres and become respirable when disturbed is very low. jonathanc Guest. weberfloor DPM is a two-component epoxy based chemical damp proof membrane that is capable of being applied in one coat, dependent upon the condition of the substrate and quality of workmanship to ensure full coverage is achieved at the required thickness. P. Complete range, complete solution. Made from recycled materials. studs 63mm x 38mm at maximum 600mm centres. The rest of the floor will be as follows (top down); flooring. Alternatively, a mechanical key for the subsequent application of levelling materials such as a screed can be created by sprinkling fine washed sharp sand or kiln dried graded quartzFintan has travelled to Baden Württemberg in Germany to study passive housing and sustainable energy technology, gaining significant knowledge regarding the use of natural insulations in timber frame and solid wall constructions. I think underfloor heating would work if you layed DPM, insulation (as much as poss) woodchip flooring and don't use a screed. below this liquid screed I am adding 50mm EPS100 to build up the depth (which reduces the thickness of the screed) and also to fix the UFH pipes to. The insulation should not be stepped as this can act as an anchor point and cause cracking in bridging or on the screed under movement and cause weak spots in a void underneath. What the DPM is attached to can fail. 5kg multi chamber bags. Yes run the dpm up the wall to connect wall dpc with floor dpm. We used the Ultra Floor system, Ultra DPM-it,. Is this okay? Or does this present a real risk of corrosion of the frame in the future?that's rising damp mate, need to dig up subfloor new concrete base, dpm leave 30 days then screed and surface membrane that should help fix the problem. 4 Apr 2017. DPM’s can be applied to either a suitable blinding layer under the slab or internally to the top of the slab. I've read that you shouldn't install DPM under SPC flooring as it can affect how it clicks together 3. TiT. 100 hardcore, 50mm builder's sand to blind, 1200 gauge DPM, 70mm insulation (Celotex, Kingspan, etc. 17 May 2010. LAY DAMP PROOF MEMBRANE. Types of Liquid DPM. Hence we always say DONT apply a surface dpm to a subfloor subject to rising damp. Non-structural floor screeds shall be adequate for the location and intended use, and provide a suitable background for floor finishes. In any case, it’s best to use a specialist to avoid damaging the floorboards themselves. The excellent adhesive qualities and quick drying time of Drybase Liquid-Applied DPM make it extremely versatile. If I did my external one at the same height then the outside floor height would sit very low so presumably I can put the external one at the same level as. There is a membrane underneath the concrete slab which has been poured and it comes up and meets the dpc. 5m x 100m, 2m x 100m, and 2m x 50m. 3. Gaz, you need to change your message setting as I can't reply. Vac up any loose sand once it's set and then tile. A floor screed is usually a cementitious material made from a 1:3 or 1:4. With a laser. Laying new floor - needs DPM? dunroving Posts: 1,881 Forumite. In terms of where the insulation should be placed, it can either be placed under the slab or between the slab and the floor screed. Once set, you can then apply your screed flooring to the DPM. Changed mate!constructed as a separate concrete (Figure 2) or concrete masonry (Figure 3) perimeter foundation wall with the slab laid later. e. It's a small garden room with a 2 course brink plinth, DPC, and then timber sole plate. (DPM) between the concrete and screed. You also mentioned that there are vinyl tiles over the floor. Hi All come across this forum and would really appreciate some assistance. Ltd. The Epoxy DPM 5kg is supplied in two 2. A traditional sand and cement screed is normally a 1:4 or a 1:3. Why is a. pipes or cables for under floor heating should always be installed on top of the tanking membrane, not beneath it. What you don't want to do, with a DPM under the screed, is create a moisture trap - which a second DPM would do. TF. Non-structural floor screeds shall be adequate for the location and intended use, and provide a suitable background for floor finishes. This can only normally be guaranteed if its an new build or extension and most houses have been sold, inherited etc. DPM is usually below the concrete, then the insulation, then a polythene sheet. The company keeps abreast of market developments by. 19 Mar 2011. Our expert team are ready to offer you the very best solution for waterproofing. Damp Proof Membranes. #1. Magnesite must be completely removed. For a self-levelling screed a system such as Flowcrete UK’s Hydraseal would be used. take account of possible differential movement. "Your insurance company should be able to instruct property drying. above the slab I am having a screed to cover the UFH pipes. 500g Single Wound Polythene-2. heating installations with cementious screeds provided a temperature of 27°C is not exceeded. A laminate wll be glued onto that. I am happy to employ gs guy to do pipe and install boiler but don't want to be calling the guy several times months appart, hence the attempt to make. Self levelling compound was laid straight on top of the concrete floor (with no primer). co. In both cases the surface on which the dpm is laid needs to be as smooth as possible. You could asphalt but it will eventually fail one day and you'll need to do it again although it is the cheaper immediate option. We are one of the leading manufacturers of advanced barrier technologies and design-based solutions for specifiers, contractors and builders merchants throughout the UK and Europe, you can count on Visqueen for product quality. e. now what i know of screeding is very little but i can do a good job i have used in the past chicken wire under floor insulation, slurry coats on concrete etc but the guy who wants the job doing is going on about a barrier around. 75mm pir but we have decided on 100. This essentially means that the screed has been laid in direct contact against the bottom of the aluminium door frame. Using pin m/m's on a concrete or s&c screed floor needs experience - more important is what is the composition of the slab or the in-situ screed and if there is an actual DPM below the floor. Effectively, a damp proof membrane (DPM) is used to create a barrier between a concrete (or screed) subfloor and a wood floor. With the power of hindsight I would have made the slab the same size as the structure so the bricks were flush with the edge then left enough DPM to run. A hydronic setup is connected to your central heating system, powered by a boiler or some form of renewable tech (eg a heat pump). Water is added to ensure a thorough mix and to aid workability. #2. I would say the screed was. For reference, screed is a thin layer of concrete poured over a floor base. Where a concrete slab or a screed is to be poured on top, the VCL will also protect the foil face of the board from alkalis within the concrete, and stop poured concrete opening board joints and causing a thermal break. Ask yourself where the gallons and gallons of water in the slab are going to go - apart from potentially lifting the DPM it will come through any defects in the DPM and cause problems. It is a thermally effective solution that is equally efficient in concrete floors, beam and block floors, and suspended timber floors. Visqueen EcoMembrane DPM. Will prim t be okay as primer on top of turbo? Thanks Pete Unless designed otherwise, the minimum specification for all partitions should be: sill and head plates 63mm x 38mm. water will be likely to collect between the DPM and the old floor. The insulation level and fabric of the building should always be factored into an underfloor. 50mm C&S (1:4) screed towelled smooth. The option of 50mm insulation between battens is appealing. 67. Curing under polythene 12 hrs 12 hrs Drying time to receive finishes - from removal of curing polythene sheet 50mm thickness and 50% RH. Sealing a patch of DPM around its edge to the old is easy, just use silicone goo. I really need to get the living room useable for my family and am hoping that a dpm under the engineered wood is possible. 9% screeds been down since February. Posted July 28, 2021. A suitable gauge damp proof membrane (DPM) and thermal insulation must be provided. Issues to be taken into account include: installation. I thought common practice was to tuck the DPM under the DPC, but mine is the other way around: I'm about to start taping the insulation around the studwork and then I'm going. 300 dries very hard Bitumen is soft so not compatible. Renovation property: £60 to £85 per square metre. DPM, Celotex, 1000 gauge poly, 100-150mm concrete with or without reinforcement, 50-80mm screed. floating construction then a second "slip". Now we realise this cannot be done and are trying to get out of a fix. Insulation will then go on top and the screed layer would go over the whole lot. In order to prevent damp rising through the concrete floor and causing issues, a DPM should be used under all final floor types including wood flooring, laminate, vinyl and floor tiles. It should accommodate 0mm to 5mm (or thereabouts) It will cover an area of 26m2 (4m x 6. The problem is by the time we insulate, screed and lay the flooring we will be above the dpc& membrane level by 4 inches. In this scenario, a rigid foam insulation is usual, and as you’d want the same U value in the roof, we need the same thickness of insulation. VAT £ 0. Effectively a thick plastic sheet, a damp proof membrane (DPM) is used to create a barrier between a concrete (or screed) subfloor and a wood floor. Reaction score. Staffordshire. Acknowledgement : The Concrete Society. 5m height allowed under permitted development as possible. Sunny Hampshire. 11. This DPM is a ‘thick’ plastic sheet mostly 1000 – 1200 gauge polythene material. The mat will get glued down to the screeded UFH, and then the. Information ARDEX DPM 1 C. Lay the dp membrane over the concrete slab and lapped over the brickwork. If applying a screed to Drybase® Liquid-Applied DPM, the second coat can be used as a primer if the screed is applied while the second coat is still tacky. Needs a dpm under it and i normally put one on top too - stops you accidentally sticking the boards to the insulation. 0m is a low density polythene membrane for use under floor screeds which are not subject to hydrostatic pressure, to protect buildings against moisture from the ground. How to Damp proof a floor and walls using synthaproof as a damp proof membrane is shown in this tutorial. Hi guys. • GG500 – 500kPa. The following week, I got high moisture readings (90% plus) in several places on the concrete flooring, from a hygrohood I borrowed from a local flooring company. 2. We've just had our garage converted and our builders have laid a screed floor. However, when I hammer-fix the battens to the concrete I'm going to punch holes in my DPM. 17 May 2010. Let the slab dry first. Curing Under Polythene 12 hrs 12 hrs Drying Time To Receive Finishes - from removal of curing polythene sheet 50mm thickness and 50% RH. Use polyethylene sheeting to create a waterproof membrane to ensure that there is no leakage of the screed when it is pumped in wet. Pro-Screed Gold is suitable for application over most underfloor heating systems. Small domestic areas that are going to have carpet, wood or synthetic floors as the final surface are ideal to use in conjunction with. It originally had Marley tiles stuck down with bitumen 'glue', but many of them are missing and I will remove the rest. As for the rest of the bungalow, I noted that there is DPM under most the sole plates of the original stud walls around the bathroom, but it's. weberfloor DPM can be applied on to concrete or cement based screed surfaces with a. Can anyone help me with the DPM under a stud partition? What's the usual way of putting it down when you're dividing a room. Refer to manufacturer’s guidelines. An expansion gap may be necessary around the edge of the floor finish in screed or. Temporary protection should. Then use the correct screed. C. sandwiched under the screed, were also common and usually in liquid form, e. The floor make up is compaced hard core, 125mm concrete, dpm, 100mm insulation, 75mm concrete screed ( polished and heated). The polyethene slip membrane installed over the insulation must be overlapped and sealed to prevent loss of screed. This barrier is intended to stop moisture passing from one to the other. The specific liquid DPM system will depend on the type of substrate or screed. Since that period I've take out the bitumen screed/dpm and been on the concrete slab since about mid February/March. Therfore putting foil faced boards under screed is a waste of time and is the principle reason kingspan make tissue faced boards. you need to dig up the old concrete then lay a couple inches of sharp sand. It's a small garden room with a 2 course brink plinth, DPC, and then timber sole. Two coats will provide protection up to a maximum hygrometer reading of 95% RH. If the property is 200 years old it won't have a DPM under the concrete slab so its sitting direct on. The DPM (Damp Proof Membrane) is laid under the insulation on top of a soft blinding to ensure it is not punctured. They are happy for the 25mm board to be laid on the screed, pipes clipped in then 9mm ply on top finally topped off with ceramics. You need a flooring professional to use an epoxy liquid DPM and screed suitable for this area and is not a job you should think to attempt 1 pinhole is a failed floor. Manchester • Member since 5 Jun 2015 • 64 jobs, 95% positive feedback. Most damp-proof floor coatings are applied directly to the concrete floor surface using a brush or roller. You also should have removed the vinyl tiles before priming and screeding. 28 Sandiwch damp-proof membrane. This allows for the full 5kg or just half to be mixed at once depending on the area to be covered. A full sheet DPM is 250 microns (1000 gauge) thickness or above. When applied on top of screed, it needs to have a further coating to protect it from damage such as laminate, tiles, vinyl, wood and carpets. 90 per pack | Buy now from UK Flooring Direct. Tape is a non starter. To add to this, when we bought the house about 6 months ago the existing felt roof (on the extension) had a gaping hole that was letting rain water. That about sums it up, but if your DPM is also serving as a radon barrier (even in a low risk area) the DPM should lap across the cavity (with a downstand) to seal the cavity from radon. Mapeproof One Coat is not recommended for heated subfloors where wood floor coverings are to be installed. Block and beam grout/slurry wetness. This seems to have been used in abundance before the original screed was put down. . The current recommendations for an effective damp proof membrane are that the ground should be constructed using screed with the damp proof membrane laid either on top or below that layer. Packaging: 25kg bags. Then a primer like the one you have at 4-1 then if needed another coat at 2-1. Eventually I will rip out the old floor and replace it but I would like to understand (as much as possible) what is going on under it without taking it off. g. Walkable in 6 hours. Damp proof membranes (DPMs) can be used to help resolve damp issues which already exist or to avoid damp or moisture problems in. 1955 house, recently moved in and presuming no DPM under concrete slab. The bitumen adhesive also contained the same asbestos fibres. Liquid DPMs gave the best protection but were more expensive. Other benefits. All other sheet membranes can be used with unbonded toppings. If the DPM is still wet you should have not tiled over. 1 or just a bit less. It is also recommended that light reinforcement be used. The flooring that’s going down is polyflor safety flooring it’s. you can then lay your celotex or similar then concrete then screed or dpm concrete insulation screed . DPM's must be carefully protected where folded up the perimeter walls, and lapped under the DPC particularly at door openings. . Country. Out of the 7sqm of floor i guess about 1. flooringman Well-Known Member. The DPM (Damp Proof Membrane) is laid under the insulation on top of a soft blinding to ensure it is not punctured. If there was no dpm I would suggest a uniformal distribution across the whole floor. Bostik Screedmaster Rapid DPM is a ready for use; one part, water-based damp proof membrane. A damp proof membrane (DPM) is used to create a barrier between a concrete (or screed) subfloor and the floor covering that is laid on top such as wood, ceramic or quartz tiles, laminate or carpet. The advantage of having the foundation. I always put the Celotex under the slab to ensure that it doesn't deteriorate between laying it down and screeding. 20 mm thickness should do it and im looking for the. DPM sheets should be overlapped by at least 300mm. If the DPM is still wet you should have not tiled over. Pumped anhydrite floor screeds are not much dearer than ready-mix sand/cement, costing around £25/m3 (laid to a 50mm depth). . Alan Jackson - Commercial Manager UK and Ireland - Gypsol. Energy Efficiency: Concrete floors generally possesses lofty thermal mass & this may be. My work will be (in order of layers): 1) DPM 1000 gauge with joints taped with Polythene joint tape. The position would vary in. 5mm = 2. Give it a good wipe with a damp cloth and let it dry before you start. UZIN has the right floor damp proof membranes for damp proofing floors. . The old adhesive should of been removed. I am the Managing Director of the Multi-Award Winning Speed Screed. Liquid DPM for Walls. 1 Feb 2010. It’s primarily designed for brushing onto concrete floors and fine concrete screeds. Yes. The DPM should come up in an upstand and tie into the DPC on the. BONDED VERSUS UNBONDED SCREEDS Bonded topping screed installations are the most common as this allows the minimum thickness (15mm) to be applied thus limiting the weight load on the structure. Concrete & Sand/Cement Screeds Concrete and sand/cement screeds must be dry and any laitance or surface treatments removed. It is good practice to either fit another DPM or tape the insulation joints, when adding a screed on top of inso'. . Still struggling with how to retrofit the DPM (on rough old solid concrete floor) and insulation etc Am not going to manage brilliant insulation as I failed to realise we couldn't take the DPM above the DPC ( at 150mm), even tho there is the head height. Is it possibly to lay a new insulated floor without a concrete slab, using only floor screed? For example: Level layer of hardcore; Layer of sand blinding; Damp proof membrane. Ideally there should be suitable insulation below the underfloor heating pipe to resist the heat going downwards. If you don't allow the screed to dry properly, the moisture will be trapped within the screed potentially causing failure. 75m2 at 3mm, 1. It is much easier to work on sections of the floor than try to achieve an even finish across the whole floor in one go. Flexible - easy to detail and install on site. As a waterproofer, BAL DPM is an easy two-coat system when used with BAL Self-Adhesives Butyl Tape in corners and junctions. Proposed floor is pitch pine boards secret-nailed to 2 x 2 inch battens with insulation between, onto a concrete floor not known to have a DPM under it; therefore, DPM to go under the battens. -markie-, Feb 10, 2020. This is done to maintain energy efficiency and prevent. 9. 250mu (1000G) Black Polythene Damp Proof Membrane (DPM) 4m x 25m (100m2/Roll) URN: 5004075. 250mu Polythene DPM is suitable for use as a damp proof membrane under screed floors. Also, even with 80mm screed directly over Celotex the sab can feel a bit "hollow". below this liquid screed I am adding 50mm EPS100 to build up the depth (which reduces the thickness of the screed) and also to fix the UFH pipes to. also alot of the insulation manufacturers specify a 500/1000 gauge membrane between the insulation and the screed inkpad, Aug 6, 2009 #7. 9. No mention of reinforced concrete screed. Small hole dug through 2" soft sandy concrete to reveal hardcore and soil. Spacey Super Moderator Staff Member. Once set, you can then apply your screed flooring to the DPM base. The position would vary in accordance with proposed methods of construction. For bonded screeds,4 weeks will depend on the depth - keep the screed as thin as possible - with wet UFH normally 50mm - any more will delay the drying time. It may be applied onto either a solid in-situ concrete ground floor slab or onto a precast concrete floor unit. Go for the application of a surface DPM; The third option is however quite expensive, and could turn out to be more expensive than the screed itself. Damp proof membranes (DPM) A DPM should be a minimum thickness of 1200g polythene and linked to the DPC with a minimum 100mm overlap. Kitchen floor, underfloor heating, screed and DPM. Insulate under the floor using the crawl space underneath. If the wall is very dusty I'd go round with the henry as well. The clips only pierce the thinner layer above the insulation, which is only really there to ensure an unbonded concrete/screed above. 100mm thick (can be heated) - Levelling screed (as required: self levelling compound, sand/cement screed etc) - Flooring, e. if no dpm I would blackjack 2 coats on. If you noticed the buildup wording is different to the detail drawing, it clearly shows dpm on top of concrete. 5m2 at 1mm thickness 1. Applying Damp Proof Membranes. On a job that’s had anhydrite screed pumped in, using a Wolff gm200 moisture meter readings in parts are 99. What do think? What if we're pouring one of these strong self. When sand-blinded, BAL DPM allows tiling onto difficult substrates such as steel. Hi All, I'm purchasing a new build and want to put Amtico Spacia down throughout the downstairs. apparently some of the screeds had a cold or hot bitumen in or under them. When I origianlly pulled it up it was damp under the bitumen screed/dpm around some cracks in the slab (guess trapped moisutre was trying to escape there), it dried in about 10-15 minuntes and has been done dry and. DPM under block and beam. Insulation Below A Floor Screed. Lay and level the concrete slab, allowing sufficient time to dry out, as per BS 8203. 0. DPM sheets should be overlapped by at least 300mm. Pumped anhydrite floor screeds are not much dearer than ready-mix sand/cement, costing around £25/m3 (laid. A Damp Proof Membrane or DPM is a waterproof barrier that’s introduced between your sub floor and your wood floor. . Property is mid 1960s, solid ground floor. 12 Sep 2015. •Suitable for use on cement/sand screeds containing water based under floor heating systems •Apply ARDITEX NA direct without priming JUNE 2019 (SUPERSEDES MARCH 2018) PRODUCT DATA SHEET (43) V.