rob85 Posted March 6, 2022 Share Posted March 6, 2022 I've messed up and set the block and beam too high, I now only have 150mm to the top of the bi-fold reveal and am concerned that a ufh system will leave the room permanently freezing. The back wall is only 6.66m and 3m of that is Bi fold doors but space is tight and a radiator will really make the modest dining section too small. We wanted a tiled finish, so allowing 20mm for that I've got 130mm for pir and screed; Is that a bad idea or will the room be ok? I don't want to freezing every time we sit down to eat. Link to comment Share on other sites More sharing options...
Nickfromwales Posted March 7, 2022 Share Posted March 7, 2022 (edited) 7 hours ago, rob85 said: I've messed up and set the block and beam too high, I now only have 150mm to the top of the bi-fold reveal and am concerned that a ufh system will leave the room permanently freezing. The back wall is only 6.66m and 3m of that is Bi fold doors but space is tight and a radiator will really make the modest dining section too small. We wanted a tiled finish, so allowing 20mm for that I've got 130mm for pir and screed; Is that a bad idea or will the room be ok? I don't want to freezing every time we sit down to eat. What is the intended floor covering? Porcelain tiles? If so you can get an overlay system and have all insulation. https://www.wundagroup.com/underfloor-heating/wundatherm/the-system/ Edited March 7, 2022 by Nickfromwales Link to comment Share on other sites More sharing options...
Conor Posted March 7, 2022 Share Posted March 7, 2022 If you switch to LVT or SRC (5mm) then you've room for 100mm PIR and 45mm liquid screed. Not ideal, but enough. Link to comment Share on other sites More sharing options...
dpmiller Posted March 7, 2022 Share Posted March 7, 2022 could even go phenolic instead of PIR Link to comment Share on other sites More sharing options...
Onoff Posted March 7, 2022 Share Posted March 7, 2022 21 minutes ago, Nickfromwales said: What is the intended floor covering? Porcelain tiles? If so you can get an overlay system and have all insulation. https://www.wundagroup.com/underfloor-heating/wundatherm/the-system/ What was the point of me digging down then building the floor back up with150mm of pir + the 25mm of eps when I did my bathroom given figures like this from that link? 20mm of Wundtherm Premium+ has an R-value of 0.447 (+/- 2%) 16mm of Wundatherm Premium+ has an R-value of 0.379 (+/- 2.8%) Link to comment Share on other sites More sharing options...
nod Posted March 7, 2022 Share Posted March 7, 2022 Allow more for tiles 20 mil is to tight Link to comment Share on other sites More sharing options...
Andehh Posted March 7, 2022 Share Posted March 7, 2022 (edited) Change to large sliding doors, then allow them to sit in a recess below tile flooring level? Build up floor over default level. Would create a nice flush finished floor still! Edited March 7, 2022 by Andehh Link to comment Share on other sites More sharing options...
CotswoldDoItUpper Posted March 7, 2022 Share Posted March 7, 2022 If you haven’t ordered your doors, can you just order them 20-50mm (or however much you need!) lower? Link to comment Share on other sites More sharing options...
Nickfromwales Posted March 7, 2022 Share Posted March 7, 2022 32 minutes ago, Onoff said: What was the point of me digging down then building the floor back up with150mm of pir + the 25mm of eps when I did my bathroom given figures like this from that link? 20mm of Wundtherm Premium+ has an R-value of 0.447 (+/- 2%) 16mm of Wundatherm Premium+ has an R-value of 0.379 (+/- 2.8%) You'd have had to dig out regardless, for a decent sub-structure for the overlay to go atop. You'd have tried to make the overlay panels yourself, and we'd still be tiling if you went that way The overlay needs a solid structure or it'll all disintegrate. Link to comment Share on other sites More sharing options...
JohnMo Posted March 7, 2022 Share Posted March 7, 2022 48 minutes ago, Onoff said: What was the point of me digging down then building the floor back up with150mm of pir + the 25mm of eps when I did my bathroom given figures like this from that link? 20mm of Wundtherm Premium+ has an R-value of 0.447 (+/- 2%) 16mm of Wundatherm Premium+ has an R-value of 0.379 (+/- 2.8%) The 20mm system will be loosing 2.2 W per degree per meter, you'll be loosing about 0.1 W. So it's not that good. 1 Link to comment Share on other sites More sharing options...
Onoff Posted March 7, 2022 Share Posted March 7, 2022 11 minutes ago, Nickfromwales said: You'd have had to dig out regardless, for a decent sub-structure for the overlay to go atop. You'd have tried to make the overlay panels yourself, and we'd still be tiling if you went that way The overlay needs a solid structure or it'll all disintegrate. The overlay panels would still be 3D printing! 😂 Seriously though, question still stands. Is my 175mm floor insulation with pipes in 100mm slab much better than the Wundtherm? Slab takes longer to heat etc, Wundtherm must be putting heat into the room quicker maybe etc. Are there higher downward losses with the Wundtherm (heating worms etc)? ??? Link to comment Share on other sites More sharing options...
dpmiller Posted March 7, 2022 Share Posted March 7, 2022 14 minutes ago, Onoff said: Are there higher downward losses with the Wundtherm (heating worms etc)? Yes. Link to comment Share on other sites More sharing options...
Nickfromwales Posted March 7, 2022 Share Posted March 7, 2022 (edited) 16 minutes ago, dpmiller said: Yes. Not necessarily. If it’s a 30mm system atop a 100mm layer of PIR or PUR then it’s a very efficient solution for the OP. Prob need to self level the block and beam to get a flat, uniform surface, so maybe allow 10-15mm worst case for that. Edited March 7, 2022 by Nickfromwales Link to comment Share on other sites More sharing options...
dpmiller Posted March 7, 2022 Share Posted March 7, 2022 Clive didn't mention any other insulation? Link to comment Share on other sites More sharing options...
Nickfromwales Posted March 7, 2022 Share Posted March 7, 2022 11 minutes ago, dpmiller said: Clive didn't mention any other insulation? Hence my phrasing “not necessarily” Link to comment Share on other sites More sharing options...
Onoff Posted March 7, 2022 Share Posted March 7, 2022 15 minutes ago, dpmiller said: Clive didn't mention any other insulation? Exactly. The way the Wundtherm spiel above puts it, to get the values quoted there is no insulation underneath, just the 16 or 20mm system boards Link to comment Share on other sites More sharing options...
JohnMo Posted March 7, 2022 Share Posted March 7, 2022 Remember the insulation value they are quoting is R value, not U value. 1/R = U. So in simple terms. 1/0.447= 2.24 U value; which is pants. Link to comment Share on other sites More sharing options...
Nickfromwales Posted March 7, 2022 Share Posted March 7, 2022 I think it’s assumed that the overlay would either be a compromise / get out of jail solution, or would be atop an already insulated substrate. Let’s not get our knickers in a twist over a retrofit solution “it is what it is”. Link to comment Share on other sites More sharing options...
Temp Posted March 7, 2022 Share Posted March 7, 2022 16 hours ago, rob85 said: I've messed up and set the block and beam too high, I now only have 150mm to the top of the bi-fold reveal and am concerned that a ufh system will leave the room permanently freezing. The back wall is only 6.66m and 3m of that is Bi fold doors but space is tight and a radiator will really make the modest dining section too small. We wanted a tiled finish, so allowing 20mm for that I've got 130mm for pir and screed; Is that a bad idea or will the room be ok? I don't want to freezing every time we sit down to eat. We have beam and block with 80mm pir and a mix of screed and stone and engineered wood floor. We run the oil fired UFH at 50C. It heats rooms fine but if I was building again I'd put in a lot more insulation as it's not cheap to run. Link to comment Share on other sites More sharing options...
rob85 Posted March 7, 2022 Author Share Posted March 7, 2022 Apparently I haven't accounted for the sill of the door which gives me a bit more breathing room, It still seems inadequate though. If I went 80mm pir, 50mm screed and 20mm wundertherm would that be significantly better than 100mm pir and 50mm screed? Link to comment Share on other sites More sharing options...
Temp Posted March 7, 2022 Share Posted March 7, 2022 (edited) As I understand it the best insulation known to man is Aerogel (fragile and expensive) followed by PIR. So I think I'd go for 100mm PIR with UFH pipe in screed. To get down to 50mm screed I think you need a liquid screed. Be careful of Anhydrite screeds as they can need more prep before tiling onto them. Here it mentions screed with UFH at 35mm. Wonder how you get the pipes flat enough. https://www.easymixconcrete.com/news/types-of-screed/ Edited March 7, 2022 by Temp Link to comment Share on other sites More sharing options...
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