Post and beam Posted February 5 Share Posted February 5 Is there a practical or recommended maximum depth of the quick pour type liquid screed used to bury UFH pipes please? I have always imagined that we would use 50mm when we get to that stage. For no other reason than this is the most often discussed depth that people seem to use. For example on Forums such as this. Why re invent the wheel. But my actual construction drawings from the TF company show 75mm cement and sand 'dry' mix. To maintain levels, thresholds etc can i specify 75mm wet pour screed, does it matter which, or is there some reason for the difference that i am ignorant of? Keith Link to comment Share on other sites More sharing options...
joe90 Posted February 5 Share Posted February 5 Mine was about 70mm, no cracks in doorways or anywhere else. Link to comment Share on other sites More sharing options...
Post and beam Posted February 5 Author Share Posted February 5 Is it the liquid quick pour stuff or dry mix sand & cement though? Link to comment Share on other sites More sharing options...
joe90 Posted February 5 Share Posted February 5 Liquid quick pour. Link to comment Share on other sites More sharing options...
Russell griffiths Posted February 5 Share Posted February 5 Why not work out the cost of 75mm thats a lot more product if you have a good size area. could be cheaper to go traditional sand and cement, or add 25mm more insulation. Link to comment Share on other sites More sharing options...
saveasteading Posted February 5 Share Posted February 5 Liquid screed will take one day, but dry mix will take several. 50mm is fine if your insulation is level and the pipes aren't sticking up. The advantage of dry mix might be that it can be phased if you are tight for space, and diy if your back is up to it. I once saw a guy laying 800m2 of 100mm dry mix. Took 2 weeks for him and a barrower. Not my choice of job. Link to comment Share on other sites More sharing options...
Post and beam Posted February 5 Author Share Posted February 5 40 minutes ago, Russell griffiths said: could be cheaper to go traditional sand and cement Agree. First question is/was to understand if liquid screed is good at 75mm. It might be that sand & cement is cheaper and the TF guys have opted for it on that basis. Total ground floor area is 114 square metres. I dont have a cost for either method at the moment so cannot yet make the call. Link to comment Share on other sites More sharing options...
Post and beam Posted February 5 Author Share Posted February 5 4 minutes ago, saveasteading said: if your back is up to it Yeah, that's not happening Link to comment Share on other sites More sharing options...
saveasteading Posted February 5 Share Posted February 5 1 minute ago, Post and beam said: might be that sand & cement is cheaper To buy yes it's much cheaper. To lay? No. Link to comment Share on other sites More sharing options...
joe90 Posted February 5 Share Posted February 5 1 minute ago, saveasteading said: To buy yes it's much cheaper. To lay? No. Yes my builder used liquid screed as it was cheaper than paying his guys to lay sand and cement screed. Link to comment Share on other sites More sharing options...
Kelvin Posted February 5 Share Posted February 5 (edited) Architects seem to default to 75mm sand and cement. I put 55mm liquid screed in and upped the depth of insulation. Cost me £4300 for 1452. Took me a couple of days to prep the floor (lay insulation, upstand, perimeter expansion foam, membrane) Took the UFH guys a day to put all the pipes and manifold in, test and fill. Took the liquid screed guys two hours from start to finish to flow the screed. Edited February 5 by Kelvin Link to comment Share on other sites More sharing options...
saveasteading Posted February 5 Share Posted February 5 9 minutes ago, Kelvin said: Cost me £4300 for 145m2 Yes about £30/ m2 for us too. Dry mix material for 60mm will only cost about £7/m2 delivered, but there follows shovelling, barrowing, spreading tamping and trowelling, perhaps into the night So Kelvin could have saved £3k with 3 fit person diy. Decisions? Pump mix obv. BTW, pump screed may crack, drymix won't, but it doesn't matter. Link to comment Share on other sites More sharing options...
Conor Posted February 5 Share Posted February 5 An extra 25mm insulation is a no-brainer 1 Link to comment Share on other sites More sharing options...
Alan Ambrose Posted February 5 Share Posted February 5 >>> Took the liquid screed guys two hours from start to finish to flow the screed. Can I ask - did it end up properly flat? Link to comment Share on other sites More sharing options...
crooksey Posted February 5 Share Posted February 5 Extra insulation would be the best bet, unless you already have 200mm then arguably there really is no point. Having a thicker floor screed does increase the thermal mass of your heating system, and may have been designed for this. Without knowing the full spec of the existing build its hard to say, you paid an architect a lot of money (i presume) so ask them why they specified a screed of this thickness over extra insulation etc. Link to comment Share on other sites More sharing options...
Russell griffiths Posted February 5 Share Posted February 5 1 hour ago, saveasteading said: To buy yes it's much cheaper. To lay? No. Would disagree with that one. 180m in traditional was £3500 for mine, liquid flow screed was about £5000 Link to comment Share on other sites More sharing options...
saveasteading Posted February 5 Share Posted February 5 2 hours ago, Russell griffiths said: Would disagree with that one Thanks. Always happy to be corrected. I think you may have done well to find someone with the skill. No risk of floating the pir either. Was it an issue to get the dry mix to bed under the ufh pipes? Link to comment Share on other sites More sharing options...
saveasteading Posted February 5 Share Posted February 5 There is a 3rd way, which would be the cheapest but I haven't tested it. I discussed it with one of the concrete suppliers, who did not offer the proprietary screed mix. He said they offered a screed mix, made of normal sand and cement, but with small aggregate and a plasticiser. So it would apparently flow as well as Cemfloor etc but at normal concrete prices, which is about half, I think. We couldn't try it though because the specialist floor laying contractors weren't interested/ prepared to use it. Link to comment Share on other sites More sharing options...
Kelvin Posted February 5 Share Posted February 5 3 hours ago, Alan Ambrose said: >>> Took the liquid screed guys two hours from start to finish to flow the screed. Can I ask - did it end up properly flat? Yep. Link to comment Share on other sites More sharing options...
saveasteading Posted February 5 Share Posted February 5 (edited) 46 minutes ago, Kelvin said: did it end up properly flat? Ours did. Yes lovely and flat, and good for level too. For level control they put down some tiny tripods with a screw adjustable probe that gets lowered to finished screed level. They are spread around at about 3m intervals and the screed flows towards them . When getting up to level the hose man just points it somewhere else or edges forwards . I can't recall seeing them float it, as it was simply poured by skill and experience and it self levels. They just walk through the wet stuff if necessary, to lift the tripods out and it re-levels. The boss did all of that and 2 labourers not a lot, except unloading at the start and cleaning up at the end. They put in strips of mdf to form crack inducing gaps, pulling them out when the screed set enough. I didn't check the levels with a spirit level and straight edge, because it looked right at any reference points, and didn't cross my mind that there might be any issue, but the tiles went down without any suggestion of humps or hollows. Our only slight issue was that they had to pour it in a circuit, so got back to the start after about 3 hours, where the first lot was getting a bit stiff. No problem though. There is one crack where another control gap would have helped. Edited February 5 by saveasteading Link to comment Share on other sites More sharing options...
Buzz Posted February 5 Share Posted February 5 5 hours ago, Post and beam said: Agree. First question is/was to understand if liquid screed is good at 75mm. It might be that sand & cement is cheaper and the TF guys have opted for it on that basis. Total ground floor area is 114 square metres. I dont have a cost for either method at the moment so cannot yet make the call. Hi @Post and beam , to give you and idea we had 250m2 at 55mm thick and paid £3900 worked out at £260 ish per m3 , they started at 8 and were long gone by lunchtime. Link to comment Share on other sites More sharing options...
saveasteading Posted February 10 Share Posted February 10 On 05/02/2024 at 19:44, saveasteading said: didn't check the levels with a spirit level and straight edge, I'm at the steading and the floor I'd clear so i have looked closely at the finish. There are ripples which won't affect tiling but will need to be rubbed off with a stone where vinyl is going It is utterly flat. The official test is a 3m straightedge, which you lay every direction and also press down one end at a time. There is nothing noticeable at all. It's flat. It has done that by gravity so must be level too. Link to comment Share on other sites More sharing options...
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