PeterW Posted July 23, 2017 Share Posted July 23, 2017 If you can tell the difference between the mass concrete sound of a solid 100mm slab vs one with hollows then you're better than me ...!! Mine is solid as a rock - although I used the Wunda trays ... Link to comment Share on other sites More sharing options...
Russ P Posted July 23, 2017 Author Share Posted July 23, 2017 I was going to do it the way everyone has suggested and tie the pipe to reinforcing mesh so no tray required Link to comment Share on other sites More sharing options...
Onoff Posted July 23, 2017 Share Posted July 23, 2017 Just now, Russ P said: I was going to do it the way everyone has suggested and tie the pipe to reinforcing mesh so no tray required You will then need a second membrane between foil face of PIR and concrete. You'll also need to mount the mesh up in the slab a bit on stand offs. Link to comment Share on other sites More sharing options...
Onoff Posted July 23, 2017 Share Posted July 23, 2017 49 minutes ago, PeterW said: If you can tell the difference between the mass concrete sound of a solid 100mm slab vs one with hollows then you're better than me ...!! Mine is solid as a rock - although I used the Wunda trays ... Dunno, maybe my dodgy mix! (Sorry, meant to Hoover the tray but dead handy for sweeping crap into). Link to comment Share on other sites More sharing options...
Russ P Posted July 24, 2017 Author Share Posted July 24, 2017 12 hours ago, Onoff said: You will then need a second membrane between foil face of PIR and concrete. You'll also need to mount the mesh up in the slab a bit on stand offs. What's the second membrane for? And yeah I had read I need the stands to lift the mesh. 40/50 ones so the mesh is half way in the slab. Will 200 be enough for roughly 8/9 sheets 8x4 Link to comment Share on other sites More sharing options...
Onoff Posted July 24, 2017 Share Posted July 24, 2017 36 minutes ago, Russ P said: What's the second membrane for? And yeah I had read I need the stands to lift the mesh. 40/50 ones so the mesh is half way in the slab. Will 200 be enough for roughly 8/9 sheets 8x4 The second membrane is simply to separate the foil face of the PIR (Celotex etc) from the concrete as you get a chemical reaction. This membrane is often thinner than the DPM. Good blog here somewhere showing someone putting it down before they had it screeded I think. Link to that anyone? I used A142 mesh btw further to suggestion here. Sorry, "200" what; £, mm? Link to comment Share on other sites More sharing options...
Nickfromwales Posted July 24, 2017 Share Posted July 24, 2017 Qty . 1 Link to comment Share on other sites More sharing options...
Dudda Posted July 24, 2017 Share Posted July 24, 2017 2 hours ago, Russ P said: What's the second membrane for? The membrane on top of the insulation is also useful to stop any concrete seeping between the gaps where the sheets of insulation are butt jointed or tape becomes loose if you've taped the joints. This concrete that seeps down creates a thermal bridge which can create a cold spot and also at it's the wetter part of the concrete that will seep down it can allow the concrete to dry out unevenly and even hairline crack. Not a huge issue with a regular floor but important for polished concrete floors. It's just an additional layer of protection usually 1000g plastic so not expensive. 1 Link to comment Share on other sites More sharing options...
Russ P Posted July 24, 2017 Author Share Posted July 24, 2017 11 hours ago, Onoff said: The second membrane is simply to separate the foil face of the PIR (Celotex etc) from the concrete as you get a chemical reaction. This membrane is often thinner than the DPM. Good blog here somewhere showing someone putting it down before they had it screeded I think. Link to that anyone? I used A142 mesh btw further to suggestion here. Sorry, "200" what; £, mm? The 200 is quantity of stands for the mesh to sit on Link to comment Share on other sites More sharing options...
Russ P Posted July 30, 2017 Author Share Posted July 30, 2017 So today I have downloaded LoopCad and had a play. Best lay out is 2 circuits and it says that between the 2 I need 109.4metres of pipe at 150mm spacing. I have 200m of pipe so am wondering whether to cut the spacing to 100mm instead! See the plans for reference but please excuse the lame attempt at units with all the diagonal lines Link to comment Share on other sites More sharing options...
Nickfromwales Posted July 30, 2017 Share Posted July 30, 2017 I don't ever lay 'serpentine' as it's a pita and doesn't heat evenly. I much prefer reverse / inverted TBH. That way you only have one or two tight 180o bends in the middle of the loop rather than the 36 or more you have in your first revision . Link to comment Share on other sites More sharing options...
Russ P Posted July 30, 2017 Author Share Posted July 30, 2017 This is the layout plan for that one then. Looks a little tight in 2places Link to comment Share on other sites More sharing options...
Nickfromwales Posted July 30, 2017 Share Posted July 30, 2017 That's just computer generated free waffle. Get a piece of graph paper and you'll draw out a much better layout in minutes. Scrap copies first so you can just bin them until its looking good. . Link to comment Share on other sites More sharing options...
Russ P Posted August 21, 2017 Author Share Posted August 21, 2017 So today was the start of the floor dig. Managed to get a breaker on what turned out to be a 4 inch quarry tile and concrete slab to expose the soil base. Tomorrow we dig down the final 5-6 inches 2 Link to comment Share on other sites More sharing options...
oranjeboom Posted August 22, 2017 Share Posted August 22, 2017 On 7/24/2017 at 21:15, Russ P said: The 200 is quantity of stands for the mesh to sit on I think I have read you need 4-6 stands/sqm of mesh. Expensive little critters too. Cheapest I have found are on fleabay so far. Most local BM don't stock 25-30mm stands it seems so a hefty shipment fee slapped on top of their £30 cost. I'll need circa 1000 of the buggers. If you are having 100mm slab, then 40/50mm spacers may be too high: Pipework: 16 Mesh (A142): 16 - 32 Spacer:40 So from insulation to top or pipework could be 72-88mm high. Depends on pipesize of course, and also whether you have any areas that have overlapping mesh. Depends on how you lay the mesh and whether you arrange it so that any overlaps 'fit in' (16mm + 8mm) or 'double up' (16mm+ 16mm). That kitchen looks as though you could get away with two carefully large sheets (4.8m x 2.4). If you can leave the sheets as big as you can and have them ready cut around walls, corners etc, that will mean less addotional bits of mesh here and there. Even with my careful cutting, I ended up with some areas of mesh that are 32mm thick, so I'm going for the smaller 25/30mm stands that should give me 30mm clearance from the top of pipes to surface of concrete: Where I have a double overlap of mesh (27mm clearance) Pipework: 16 Mesh (A142): 32 Spacer:25 Where I have a 'mesh and a half' overlap of mesh (30mm clearance) Pipework: 16 Mesh (A142): 24 Spacer:30 I went with standard DPM for the areas that used PIR as it's a bit tougher when you're buggering around with the mesh. I'd also lay the mesh on top of the DPM, add your UFH and only then fit the spacers underneath. No point tripping up whilst laying the UFH that way. Link to comment Share on other sites More sharing options...
PeterW Posted August 22, 2017 Share Posted August 22, 2017 What's wrong with broken concrete paving slabs ...?? Got to be cheaper...! 1 Link to comment Share on other sites More sharing options...
Onoff Posted August 22, 2017 Share Posted August 22, 2017 How about these as an alternative? Link to comment Share on other sites More sharing options...
Barney12 Posted August 22, 2017 Share Posted August 22, 2017 If you do use those little plastic cones then I wouldn't put them in until you've tied the UFH pipe to the mesh. The weight of people walking on them will just see them collapse. Or perhaps the ones we had were just cheap rubbish I think @PeterW idea is fine. I can't think of a technical reason as to why not too? Link to comment Share on other sites More sharing options...
oranjeboom Posted August 22, 2017 Share Posted August 22, 2017 2 hours ago, Onoff said: How about these as an alternative? Would you recommend margarita? Thin crust would probably be better as less chance for those air bubbles to appear? I better start ordering.... 11 minutes ago, Barney12 said: If you do use those little plastic cones then I wouldn't put them in until you've tied the UFH pipe to the mesh. The weight of people walking on them will just see them collapse. Or perhaps the ones we had were just cheap rubbish I think @PeterW idea is fine. I can't think of a technical reason as to why not too? Yeah, when I had the piled slab done, I had to go round and replace all the squished supports as they do just collapse. I think you can buy premium ones though. The slabs I have lying around were going to be used for my below ground EWI protection, but it may be worth ordering some more and cutting those up for supports. Link to comment Share on other sites More sharing options...
Jeremy Harris Posted August 22, 2017 Share Posted August 22, 2017 (edited) "mars bars" are pretty near indestructible, and can be broken into shorter lengths, as required: http://www.siteright.net/concrete-square-p-195.html or http://www.lemon-gs.co.uk/shop/concrete-square-bar-spacers.html Edited August 22, 2017 by JSHarris Link to comment Share on other sites More sharing options...
Russ P Posted August 22, 2017 Author Share Posted August 22, 2017 Ive bought the slightly more expensive concrete mesh men from TP. As for the mesh height it shouldn't be any higher as it sits into the stands so hopefully to top of pipe will be 56-66mm! Finished digging today and started DPM and insulation! Got a bit of drainage work to do first thing then get rest of insulation down! Target for tomorrow is all pipework laid Link to comment Share on other sites More sharing options...
Russ P Posted August 23, 2017 Author Share Posted August 23, 2017 so finished insulating and got all my pipework laid. 1 Link to comment Share on other sites More sharing options...
Onoff Posted August 23, 2017 Share Posted August 23, 2017 What photographic trickery is this? Dug and built back in days!!! 2 Link to comment Share on other sites More sharing options...
Russ P Posted August 23, 2017 Author Share Posted August 23, 2017 (edited) 7 hours ago, Onoff said: What photographic trickery is this? Dug and built back in days!!! I wish there was trickery involved lol I wouldn't be so [ever so slightly tired] ! ??? Edited August 23, 2017 by PeterW To put nice words in it ... 1 Link to comment Share on other sites More sharing options...
bassanclan Posted August 23, 2017 Share Posted August 23, 2017 Looks good. why did you choose that pipe layout? Generally going in ever decreasing circles is better for temperature evenness and less tight bends on the pipe Link to comment Share on other sites More sharing options...
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