Evs Posted February 16, 2021 Share Posted February 16, 2021 (edited) Hi guys, I’m currently doing a self build and am going to be installing UFH on the ground and first floor. The ground floor is pretty straight forwards as its constructed from beam and block, so ontop of that is my 100mm insulation, ufh pipes will clip into that and then 50mm of screed poured on top. The house is an upside down layout with the bedrooms on the ground floor and the kitchen, dining, living room etc on the first floor. This first floor is a suspended floor sat on easi-joists so spreader plates can’t be used for the under floor heating (well, so I’m told). Therefor I was going to put 22m floor boards down ontop of the easi joists, then 20mm thick loflo lite panels. According to the suppliers I need to put a 3mm adhesive layer below the panels and a 5-6mm adhesive layer ontop of the panels to allow me to tile directly on top of the panels. I just wondered if there is another option that would work out cheaper as the panels and adhesive are coming in at £2300 alone. I thought about using 18mm floor boards, then stick foiled back insulation down on that, batten the floor with 25mm batten and clip the ufh pipes inbetween the battens and ontop of the foil backed insulation. Then I’d have to put floor boards ontop of the battens and a layer of adhesive ontop to be able to tile over this, as the whole ground floor is being tiled. The only problem with this is raising my floor height too much, I’d be rasing it 60 odd mm as apposed to 40 odd when using the loflo panels. The brickies have allowed for 45mm increase in floor level when constructing the door openings. Edited February 16, 2021 by Evs Link to comment Share on other sites More sharing options...
ProDave Posted February 16, 2021 Share Posted February 16, 2021 The reason you have been told you can't use spreader plates on metal web joists is because you cannot notch the top of the joists to allow a pipe to pass over the joist, and it would be nigh on impossible to thread the pipe through the joist at every transition. You can however batten over the top of these joists, leave a gap in the battens where a pipe needs to cross a joist, then use spreader plates and normal floor boards. 1 Link to comment Share on other sites More sharing options...
Evs Posted February 16, 2021 Author Share Posted February 16, 2021 3 minutes ago, ProDave said: The reason you have been told you can't use spreader plates on metal web joists is because you cannot notch the top of the joists to allow a pipe to pass over the joist, and it would be nigh on impossible to thread the pipe through the joist at every transition. You can however batten over the top of these joists, leave a gap in the battens where a pipe needs to cross a joist, then use spreader plates and normal floor boards. Why the hell didn’t I think of that! ? Thank you Dave. Link to comment Share on other sites More sharing options...
BotusBuild Posted February 16, 2021 Share Posted February 16, 2021 3 minutes ago, Evs said: Why the hell didn’t I think of that! A problem many of us have from time to time - too close to the action ? Link to comment Share on other sites More sharing options...
Evs Posted February 16, 2021 Author Share Posted February 16, 2021 Just been thinking about this, if I use the loflo boards will I still need to insulate inbetween the joists with rockwool? My building regs require 100mm rockwool inbetween joisted floors but if I use the loflo boards does anyone know if I’ll still have to use the rockwool? Link to comment Share on other sites More sharing options...
Russell griffiths Posted February 16, 2021 Share Posted February 16, 2021 I would also look at your downstairs insulation 100mm is not enough over block n beam. Link to comment Share on other sites More sharing options...
Evs Posted February 16, 2021 Author Share Posted February 16, 2021 (edited) 49 minutes ago, Russell griffiths said: I would also look at your downstairs insulation 100mm is not enough over block n beam. This is what my architect has put on my drawings. Would you go with 150mm? Only problem now is I think it may be too late, as all my door openings have been blocked adhering to the drawings which state 100mm insulation and 50mm screed. Therefor if I was to go with 150mm I’ll be increasing my floor height by 50mm. Edited February 16, 2021 by Evs Link to comment Share on other sites More sharing options...
Russell griffiths Posted February 16, 2021 Share Posted February 16, 2021 I believe 100mm is just about building regs standard. Link to comment Share on other sites More sharing options...
Evs Posted February 16, 2021 Author Share Posted February 16, 2021 30 minutes ago, Russell griffiths said: I believe 100mm is just about building regs standard. Ah right ok. I haven’t layed the insulation on the floor yet so I’ll measure it tomorrow so see if I have any room to increase it. Link to comment Share on other sites More sharing options...
SteamyTea Posted February 17, 2021 Share Posted February 17, 2021 I think 100mm of celecotex gives a u-value of 0.22 W.m-2.K-1 If your UFH is running at 35°C and the void under the block and beam is at 5°C, that is ~7W.m-2 or 0.16 kWh.day-1. Keep adding in floor insulation. Link to comment Share on other sites More sharing options...
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