Had a look at the pics and IMO no dpm under the subfloor. Used the primer neat as guidelines suggested. For unbonded and floating screeds, a DPM may be specified between the base slab and the screed. B. Block and beam grout/slurry wetness. The liquid membrane forms a strong seal and makes a permeable layer to enable moisture to evaporate off. To help determine the cost of a screed floor let’s look at the average prices people pay. Screed & Insulation. TB243. For technical support please call. The 'vapour barrier' attached to your underlay will only protect your floor from a slab reading 75% RH or less. 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. 67. Use a thick bed adhesive unless your competent to use screed, it takes skill and practice to create a flat floor. 40mm traditional sand and cement screed. The dpm needs to be clean and dry. The polythene damp proof membrane (DPM) – generally a 1200 gauge- can now be rolled out into place ensuring the perimeter abutments are adequately covered. Anyway, my DPC/DPM seems to have been done wrong, but I just wanted to ask what I should do next to make it work. We've just had our garage converted and our builders have laid a screed floor. Then a primer like the one you have at 4-1 then if needed another coat at 2-1. The screed will be only ~50 max (not yet dug any up). If the concrete in-fill is low, after patching the DPM, putting the screed on it will cause the centre of the DPM to drop and pull away at your new seal around its. The DPM should: have sealed laps of at least 300mm wide link with wall DPCs to form an impervious barrier to. Assuming that the damp proof membrane (dpm) under the concrete has failed in areas then yes you possibly would get the odd patch of dampness showing in the floor. Where screed is laid on top of insulation, screed should have a minimum depth of 65mm. As a rule self levelling screeds need an active DPM at some point below them other wise they will likely de-bond due to damp and this could be the reason it seems to be lifting easily. A Damp Proof Membrane or DPM is a waterproof barrier that’s introduced between your sub floor and your wood floor. 1 left. dthobhani; 18 Mar 2011; Floors, Stairs and Lofts; Replies 2 Views 1K. Liquid DPM for Walls. I was hoping to use a recycled content DPM. £18 - £22 per m2. concrete slab. 8 Oct 2015 #4 So you have a concrete slab laid on a DPM, and later a 65mm sand & cement screed laid on the Extn. . Only one coat though. Water is added to ensure a thorough mix and to aid workability. 27 Dec 2020. If in the screed then no problem with this. Country. This barrier is intended to stop moisture passing from one to the other. The Epoxy DPM 5kg is supplied in two 2. DPC and DPM are lapped together at this stage. weberfloor DPM can be applied on to concrete or cement based screed surfaces with a. either way, as the other posts say, you would be better screeding which will also take out any irregularities in the concrete. All modern buildings have what is known as a Damp Proof Course. The purpose of DPM. No mention of reinforced concrete screed. 50 /sqm. I'm thinking dpm under the floor board and then 3:1 motar under the DPM to bed on the blocks. Brian shows how to correctly fit a Damp Proof Membrain - DPM in a new build houseLink to the T-Rex tape Website Http://bodgeitwithbri. You must design out the (damp/thermal) vulnerabilities associated with raft type foundations as they can be a headache. Top. Maximum depths are around 10-15mm, however with the addition of bulking aggregates (normally kiln. Preparation is key with these coatings and the substrate must be sufficiently clean and dry. What is DPM under screed? Damp-proof membrane (often called DPM) is used in construction to prevent moisture from entering the building, usually through capillary action. Tramex reading at the time of vinyl removal was 3-4+. 00. 21. Contact Us. 17 May 2010. Based on a screed done in 1963 I’d say 95% there won’t be a effective damp proof membrane under it so a epoxy dpm should of been used like Ardex DPM1c. hours for Ceramics. Scaffold boards should be used for barrowing and tipping concrete and screed and a light mesh of chicken wire can be used over separating layers or dpms over insulation under screeds as added. Warm water underfloor heating. 250mu Polythene DPM is suitable for use as a damp proof membrane under screed floors. Mastic Asphalt – this is the earliest form of liquid DPM and is usually laid on the top of another membrane or a fibreglass surface. g. How to Damp proof a floor and walls using synthaproof as a damp proof membrane is shown in this tutorial. Country. I. We used the Ultra Floor system, Ultra DPM-it,. It has had an extension about 50 years ago and that is the problem room as the flooring was laid without any DPM under the existing concrete floor, so there are some rising damp issues (I think). Insulation is a crucial consideration for UFH. first of all check your existing floor is perfectly level, if not then forget the freeflowing screed as it will not level up with the existing floor. Nice. #1. Should I lap DPM under or over Dpc then celotex, then another DPM lapped up the wall with 25mm up stands. Small hole dug through 2" soft sandy concrete to reveal hardcore and soil. No this is designed to be used under floor screeds, tiles, render or plaster. The DPM (Damp Proof Membrane) is laid under the insulation on top of a soft blinding to ensure it is not punctured. Screeds are covered by BS 8204, Screeds, bases and in-situ floorings, (2004). The outcoming drain will have the dpm taped to it all the way around. The concrete slab was usually 100 to 125mm thick. If you don't allow the screed to dry properly, the moisture will be trapped within the screed potentially causing failure. Diagram B38 - DPM lapping under DPC for thickness of inner leaf. But on the basis of more insulation is better, consider fitting more and laying cupboard flooring on top, or on joists. Apply ARDEX DPM 1 C to protect the floorcovering installation from residual construction moisture and ground bearing moisture. Now we realise this cannot be done and are trying to get out of a fix. The correct installation of polythene DPM, rigid insulation and separating layers are highly important to the. The bitumen is about 20 mm thick and, I believe, serves as moisture barrier as well as an 'appearance' finish. 15 Feb 2015. The main drawback. not really, you said that you intended to use DPM under SLC, compound won't adhere to dpm and if will will install tiles to the SLC and it will crack your tiling will be spoiled, you can do SLC, next apply liquid DPM and install tiles to it- that's the way in my opinion. 19 Mar 2011. weberfloor DPM can be applied on to concrete or cement based screed surfaces with a. Watch on. It's a small garden room with a 2 course brink plinth, DPC, and then timber sole. Insulate under the floor using the crawl space underneath. JB Flooring Well-Known Member. 1200g DPM will be fine. Information ARDEX DPM 1 C. Prime and reapply , then screed to level and tile. 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. With the number of planning applications for basement extensions rising by 183% according to research by Halifax, tilers need to be. Yes it is a small breach on regs but would be up to building control to decide. screed thickness. Checkatrade offers the following guide: Electric underfloor heating cost. It may be applied onto either a solid in-situ concrete ground floor slab or onto a precast concrete floor unit. The membrane is manufactured in standard 125mu, 250mu, and 300mu thickness and in roll sizes of 1. (DPM) with joints well lapped and folded. it could easily be up and down by up to 15mm. VAT £ 0. Property is mid 1960s, solid ground floor. For the best results, we recommend leaving it to cure for 28 days. It’s primarily designed for brushing onto concrete floors and fine concrete screeds. If the insulation is going below the slab, the damp proof membrane (DPM) is laid next, followed by the insulation, a polythene separating layer, and the concrete slab. The vinyl that was laid bubbled up, so contractor removed it. Applying Damp Proof Membranes. 0113 2455450 sales@rawlinspaints. UFH Pipwork. If there is an operational DPM beneath the concrete you don't need one on top. This should be laid on a bedding material such as screed which doesn’t damage the sheet and has fully sealed joints. DPM sheets should be overlapped by at least 300mm. Brian shows how to correctly fit a Damp Proof Membrain - DPM in a new build houseLink to the T-Rex tape Website Http://bodgeitwithbri. 99 Inc Vat. We have our sub concrete floor in, and there will be a 1200g dpm, then 100mm insulation, then another dpm and finally 65-70mm screed. Screed. Ie work down from FFL. Made from recycled materials. Misinformed on this as he had put a dpm under the chipboard. 5mt x 4mt rolls | £ 56. A latex based screed isnt as affected by moisture/damp as a water based is. 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. Find. user contributions licensed under CC BY-SA. Traditional screeds. someone suggested removing the blocks on the inside along the width of the bifold and screeding all the way to the brick course. It is important to ensure that a proper seal is achieved around all services. Country. Insulation must be provided under their entire area to ensure compliance with the Building Regulations is achieved. As nod mentioned, your DPC will actually be the first layer of DPM you put down bef ore the insulation. 12 Sep 2015. At its deepest it’s 150mm, what I’m stuck with is the builders trying to push on with the job. An ARDEX Damp Proof Membrane will protect the floorcovering. 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. The installation of a liquid damp proof membrane is a vital stage in the construction process, for both new builds and refurbishment work where a structural DPM may be missing or damaged, or where residual construction moisture is present in the floor. British Standard (8204:1) says minimum 65mm for domestic floating. . Onto the concrete. This reduces the risk of harmful interstitial condensation by ensuring that any moisture within the. Unless there is an easy way. 17 May 2010. Don't use a bitumen at all, you are correct eventually your screed will fail. The guy doing it tried to compensate by using more adhesive and most of the wood has. The main issue you need to remember about the DPC at the external walls is to have an upstand on the inner leaf and slope down to the other leaf. Once set, you can then apply your screed flooring to the DPM base. Developer has quoted £3744 for approx. screed. Stack Exchange network consists of 183 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn,. Said he'd provide a quote but didn't come back to me. This allows for the full 5kg or just half to be mixed at once depending on the area to be covered. Remove and Smooth. 4) at a thickness of 3" inches The guidelines state that a damp proof membrane that is placed under the flooring should be around 1200 gauge and constructed of polyethene. 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. 5kN/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. I would guess, that a standard mix was used, as that would be cheapest, so could assume 1mm per day, but that`s why a test would be needed. 28 Sandiwch damp-proof membrane. Curing Under Polythene 12 hrs 12 hrs Drying Time To Receive Finishes - from removal of curing polythene sheet 50mm thickness and 50% RH. This site contains a wealth of information on our extensive product range, along with a selection of videos demonstrating their application. 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. My house has a solid screed floor throughout the downstairs, with a Damp proof membrane about 100mm down. I would say the screed was. I'd like to change our tiled dining room room floor to a carpeted floor with underfloor heating. 10) Timber block between U channel and Cavity Weep Holes 11) Galzing unit (window/glass) 12) Tiles glued 13) Polypropylene 14) Screed 15) DPM under screed 16) Concrete slab 300mm 17) DPM under. Alan Jackson - Commercial Manager UK and Ireland - Gypsol. Effectively, a damp proof membrane (DPM) is used to create a barrier between a concrete (or screed) subfloor and a wood floor. The specific liquid DPM system will depend on the type of substrate or screed. Use 1000 gauge or thicker – ideal for this is the polyethylene use for the DPM under your concrete subfloor. I was then able to put in a dpm and a hefty layer of cellotex and then screed to the level of the house. Figure 2: Concrete floor cast into rebate in foundation wall. Im surprised the floors lasted that long 300 will fail over bitumen everytime. Guide Underfloor heating A guide for house builders NF71 NHBC Guide to Underfloor Heating 2nd draft RH. FlexiDry said: Yes laying the screed direct onto insulation is standard practise for a floating floor. This means of course I can't get a DPM under the slab; is it ok to put the DPM over the concrete slab, and then put down 50mm insulation and then 100mm screed? Ed209 , May 1, 2020 #1Assuming that the damp proof membrane (dpm) under the concrete has failed in areas then yes you possibly would get the odd patch of dampness showing in the floor. Ltd. I've dug down and exposed part of the DPM sheet under the slab so I'm happy using trade plan, turbo then renovation screed. 100mm **concrete base*. There will be a DPM under the slab and up the edges already. Below Floor Screed 1. You also should have removed the vinyl tiles before priming and screeding. Then once the screed is dry use a liquid DPM such as F-Ball Stopgap F77. framing joints secured with not less than 2 nails per joint. 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. For rafts, DPM and screed must be on top of raft and screed must be at least 65 mm thick. 12) Tiles glued. VCLs prevent excess moisture entering a wall’s cavity, behind the insulation. If the applied DPM is still very tacky, this1. For bonded screeds, M-Bond Extra epoxy resin combined DPM and bonding agent may beToday, new solid floors are far more substantial, typically comprising 150mm of compacted hardcore, 50mm of sand, a polythene sheet DPM, 100mm of concrete, then around 100mm of insulation plus a 60mm screed — in total, more than 450mm thick. -markie-, Feb 10, 2020. It is advisable to have a minimum of 100mm insulation covered with 60-80mm screed. Renovation property: £60 to £85 per square metre. As to joining - take bricks down to the bottom of the insulation later and run your insulation (which I presume is celotex type) into the opening, screed over insulation level. If the insulation is flat and supported by the slab, 50mm screed won't crack or - spend the DPM money on a roll of 25mm chicken wire. Location. We always remove the masonry below allowing the floor screed to have a bit of 'meat' to help overcome the differential movement. e. This will leave bitumen (ironically) glue residue behind which is a problem to remove I believe - and must be completely gone. Visqueen ECO Membrane Data Sheet. Ideal for use in shower areas where screeds are laid to falls incorporating a damp proof membrane. Ideally with a screed pump. The floor make up is compaced hard core, 125mm concrete, dpm, 100mm insulation, 75mm concrete screed ( polished and heated). There is a concrete slab in place with a DPM underneath. 18) Bricks. #1. Once set, you can then apply your screed flooring to the DPM. However to get BC off your back you can use a epoxy DPM and sand scatter it before it sets. Effectively, a damp proof membrane (DPM) is used to create a barrier between a concrete (or screed) subfloor and a wood floor. They can feel wobbly when you walk on them but you get to the point when you can't get them any better and each give you walk on them or lift them you end up going around in circles. fix battens to subfloor - I can't raise the floor height with battens on the screed, but I could lift and remove the 50mm screed layer, fix 50mm battens at 400mm centres direct to the concrete slab, and then boards fixed on top of the battens. Our self levelling compound, or floor screed, is available in a wide range of varieties for a multitude of floor installation applications. 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. the DPM and new floor can then go on top of this. If Under floor heating is used It is essential that the pipes are laid on. 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. 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. Made from a combination of sand, cement and water, usually in a sand/cement mix ratio of anywhere between 3:1 and 5:1. Most damp-proof floor coatings are applied directly to the concrete floor surface using a brush or roller. You should use them to protect all final floor finishes. 5sqm has blown. Normally you would put a compacted bed of about 50mm sand under the DPM. Unbonded Sand and Cement Screed Minimum Thicknesshelppppppppppppppppppppppppp just had to quote for screed flooring. floating construction then a second "slip". 5kg multi chamber bags. I will be tiling over the screed so looking for the simplest option. Country. For guidance on using DPM One Coat Membrane with screed products refer to the individual ScreedPro Data sheet concerned. 10 Feb 2020. 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. Then mix up the high performance stuff as that is fibred and can be taken to a feather edge. Visqueen EcoMembrane DPM. Solid floor insulation –screed finish: Per m 2: £70: £90: £80: Labour: Per day: £180: £250: £215:. Registered Office: 6 Acre Close, Rustington, West Sussex BN16 3PG. Location. Posted July 28, 2021. Our highly experienced team of technical experts are here to offer help and advice every step of the way! Dependable Deliveries. 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. 15) DPM under screed. It is better to put the insulation under the concrete (which wants to be 100. Pumped Anhydrite Screeds. O and the Answer to Mapei and Uzin is no. i'n not farmiliar with wickes dpm and the primer used for professional (if you like) screeds is neoprene. 3. 24 h After curing of screedSANS 10400, Part J Floors (which is the SABS “deemed to satisfy” regs) states: “Ventilation of the subfloor space in suspended ground floors shall be provided by means of openings spaced not more than 2,4. TB243. This is resorted to only under the duress of severe time constraint. Answered 18th Aug 2020. 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. The clips only pierce the thinner layer above the insulation, which is only really there to ensure an unbonded concrete/screed above. We need to raise one level by 6mm then screed then laying 2. A few months have passed since then and is now on average 2. 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. so FBall seems the way to go). LKAB Minerals +44 (0) 7966 651006. 4 Screed. It is usual practice to lay vent pipe under concrete and dpm. When stripping the bathroom, the area under the bath tub was bare concrete, lower than the rest of the "black" floor throughout the property. Yes. Why is a. The idea is that you are to prevent any screed material from falling down any joints and coming into contact with the cold slab. Kingspan GreenGuard is available in a range of compressive strengths starting at 300 kPa 10% compression. 2 of the internal walls in the older building will be left as bare stone,. Ideal for use where there is no functioning structural DPM (common in older properties). Instead of a membrane, use a foam underlayment material which will keep the wood from touching the screed directly (avoiding any moisture transfer) but which will also allow the screed to breathe and thus dry over time. It will - I believe - deteriorate with UV light, but that won't apply to anything cover by the soil itself. Temporary protection should. DPM, Celotex, 1000 gauge poly, 100-150mm concrete with or without reinforcement, 50-80mm screed. Under Floor Heating; Screed Care; Testing; Tips; Blog; Contact; A Practical Guide to Screed Testing: What Do the Experts Say? Download. •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. you need to dig up the old concrete then lay a couple inches of sharp sand. Use a thick bed adhesive unless your competent to use screed, it takes skill and practice to create a flat floor. But too much water will extend the drying time and. One thought is to plug it at the junction under the draincover and then screed round it, and lay floor over; then it can be reinstated in future if ever needed. 21 Sep 2016. We could scrape up the tiles and start again. Our Liquid DPM can be used on walls under a render to create a flexible waterproof layer. But this all begs the question of why the hallway is so wet. This can include timber floors, tiles, laminate flooring and carpet. #1. The work falls under building regs part L and you need minimum 70mm PIR insulation. Through DPM of course so a bit of silicone down the screw hole to seal the hole. #3. Stack Exchange Network. or email. Pro-Screed Gold is moisture tolerant and can be used under and over DPM’s. Then a DPM on top to avoid them floating in the screed. Currently, the central heating pipes and mains water pipes are all buried below the damp proof membrane, under the screed. Put an upstand of 25mm celotex around the perimeter of the room and a dpm under the concrete lapped up the walls, being higher than the dpc won’t matter Jimmycloutnail, Jan 23, 2019 #4. The installation of a liquid damp proof membrane is a vital stage in the construction process, for both new builds and refurbishment work where a structural DPM may be missing or damaged, or where residual construction moisture is present in the floor. Our Epoxy DPM can be used on concrete floors and fine concrete screeds, of not less than 50mm thick in the case of un-bonded screeds. 28. Hi, Thanks for this, so it sounds like you would normally just overlap (and seal) the floor DPM and one over the threshold which extends to the outer leaf? I've filled the cavity with concrete under the door opening and poured the slab and the screed will go across the cavity to the outside leaf (which has the perimeter insulation to stop cold spots). Buy Now. It's joining onto the garage I'm converting so the whole floor is getting built up with polythene DPM,. 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. ), then 500 gauge plastic (or just use the leftover 1200 gauge DPM) then 100mm concrete slab. The floor is concrete slab, 100mm Kingspan PIR, DPM and then 70mm screed. • GG300 – 300kPa. Ground-bearing concrete floor slabs should be protected against ground moisture by providing a continuous damp proof membrane (DPM). View complete answer on allthingsflooring. Applying Damp Proof Membranes. 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. The DPM should: have sealed laps of at least 300mm wide. It needs: 100mm or more of well compacted type 1 MOT, sufficient sand to blind, DPM, insulation, screed. The oversite is then constructed internally along with polythene DPM, insulation and floor screed etc. Covering it in denso tape and maybe putting some dpm over the top before screeding? Yes copper is best and lasts forever, but in this situation what would you do? So far I'm leaving towards plastic which makes like easier, less stress thinking that there are all those copper joints under the screed and underfloor heating. PermaSEAL Liquid DPM can also be applied to concrete floors below screeds. My questions are: Is there any reason to use a roll of DPM vs a liquid. Cement screed. Pro-Screed Gold can be applied from depths of 2mm to 12mm in one application and with aggregate it can be applied up to 30mm thick. Outside ground should be. Trusted Trader, said safety must be a priority after a flood. Damp Proof Membranes. You can lay a fast track DPM (damp proof membrane) if your new concrete has had 2/3 weeks drying time. The surface should be of sufficient quality and. When stripping the bathroom, the area under the bath tub was bare concrete, lower than the rest of the "black" floor throughout the property. The liquid membrane forms a strong seal and makes a permeable layer to enable moisture to evaporate off. This allows for the full 5kg or just half to be mixed at once depending on the area to be covered. Laying new floor - needs DPM? dunroving Posts: 1,881 Forumite. It is good practice to either fit another DPM or tape the insulation joints, when adding a screed on top of inso'. #Screeding #Sc. 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. 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. Note though that this will raise the floor level by 75-100mm (depending on the insulation). Lay the dp membrane over the concrete slab and lapped over the brickwork. I 've dug down and put 100mm of concrete down will liquid dpm to meet up with the existing dpm and 50mm screed ontop easy. apparently some of the screeds had a cold or hot bitumen in or under them. My DPM was these tiles that were bitumnned/black jacked to the floor. 5mm Polyflor . #2. It would have taken a lot of screed to make up the level - about 36 bags. 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. studs 63mm x 38mm at maximum 600mm centres. UZIN has the right floor damp proof membranes for damp proofing floors. having a solid wall causes damp bridging problems for the floor (there is a dpm on top of the floor anyway, but the beam and block is supposed to sit on a dpc) as there is no cavity. It is not. I am putting down a 22mm engineered oak floor so will use an underlay without a dpm. Unbonded screeds are used either to install a damp proof membrane (dpm) between the base slab and the screed or where the base slab surface is unsuitable for a bonded screed due to problems such. When we stick any floor down to the sub floor, solid or engineered, we insist on installing a liquid DPM unless the existing is guaranteed to be 100% in tact. rogerk101 likes this. Two coats will provide protection up to a maximum hygrometer reading of 95% RH. BS8203 recommends a maximum of 75% RH prior to the installation of sensitive finishes. the advice by these two posters is absolutely incorrect, if your RH% is above 75% you absolutely need a surface dpm and dual screed the test takes 72 hours to take though, depending on size the price you were quoted is reasonable (surprisingly from Carpetright), there are certain BS you must follow for correctly preparing a sub. How to install vacuum insulation panels below a floor screed.