MortarThePoint Posted February 16, 2020 Share Posted February 16, 2020 It may be unusual, but we have designed a precast concrete product in for our ground floor. A bit more expensive than beam & block, but It has the following key benefits: has insulation already attached to its underside can be installed by manufacturer in a day and then ready for next stages puts the concrete of the floor inside the insulated envelope increasing the insulated thermal mass Due to some Made Ground on site and not wanting the vagaries of Ground Gas well testing, we decided to incorporate a gas membrane into the design which replaces the DPM. This gas membrane will be installed above the concrete floor and then ultimately have screed over the top. There is the option to do perimeter first and then infill, but cheaper to do all as one. What I am wondering is how I leave all this for the subsequent year or so as the rest of building works goes on. Options that spring to mind are: Just do perimeter and leave concrete slabs exposed (probably grouted), infill later Do full gas membrane and cover with full depth of screed (minimum 75mm) including underfloor heating pipes Do full gas membrane and partial cover with screed (? e.g. 30mm ?) to protect the gas membrane I expect people who have used Beam & Block and a gas membrane have faced the same quandary, so it would be great to get some pointers. Link to comment Share on other sites More sharing options...
bissoejosh Posted February 16, 2020 Share Posted February 16, 2020 We had beam and block + radon membrane. I did the beam and block first and slurry grouted. Then I built the walls (timber frame) and for this laid a strip of radon membrane + DPC under the sole plate which projected around 30cm into the house. Once the roof was on and I was ready to do the floor I laid the rest of the radon membrane and taped it to this strip - easy as I had already do the fiddly corners etc. Insulation, UFH and screed then followed quickly. 1 Link to comment Share on other sites More sharing options...
MortarThePoint Posted February 16, 2020 Author Share Posted February 16, 2020 38 minutes ago, bissoejosh said: We had beam and block + radon membrane. I did the beam and block first and slurry grouted. Then I built the walls (timber frame) and for this laid a strip of radon membrane + DPC under the sole plate which projected around 30cm into the house. Once the roof was on and I was ready to do the floor I laid the rest of the radon membrane and taped it to this strip - easy as I had already do the fiddly corners etc. Insulation, UFH and screed then followed quickly. Sounds sensible bissoejosh. Did you have to have verification testing done afterwards etc. I'm planning to use a specialist installer for the membrane work as then any issues with subsequent testing will be on their head rather than mine. I'd like to be an informed customer though rather than going at it without a clue, hence the thread. Link to comment Share on other sites More sharing options...
bissoejosh Posted February 17, 2020 Share Posted February 17, 2020 Just a building control inspection - actually I'm not sure they even wanted to see it but I have a lot of photo evidence. It's all a bit pointless if you ask me as the floor is suspended with air flow beneath so any radon build up will ventilate itself away. Link to comment Share on other sites More sharing options...
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