Hi,
I've heard that you shouldn't have too wide wooden floors if you have underfloor heating, due to the risk of the flooring twisting/warping. Can someone verify/disprove this theory? How wide floors can you have together with underfloor heating?
Regards,
David
I've heard that you shouldn't have too wide wooden floors if you have underfloor heating, due to the risk of the flooring twisting/warping. Can someone verify/disprove this theory? How wide floors can you have together with underfloor heating?
Regards,
David
I just decided on 20x135mm.
It's possible that there's a wider range than what I found, but given that the floor shouldn't be thicker than 20mm (more is unwise above gv), there was nothing wider than 135.
So maybe you don't need to worry too much.....:=)
I have no experience with too-wide planks, but it's certainly wise to consider any risk of warping.
/Mathias (with sore shoulders from hammering 5" nails with a small sledgehammer....)
It's possible that there's a wider range than what I found, but given that the floor shouldn't be thicker than 20mm (more is unwise above gv), there was nothing wider than 135.
So maybe you don't need to worry too much.....:=)
I have no experience with too-wide planks, but it's certainly wise to consider any risk of warping.
/Mathias (with sore shoulders from hammering 5" nails with a small sledgehammer....)
Hello,
We have at least 25x158 mm pine flooring on underfloor heating. The floor comes from Siljan and according to them, it works excellently on underfloor heating. The boards are milled on the underside, which I've heard is supposed to prevent the boards from warping/twisting.
If the floor is to serve as a load-bearing structure directly on the joists (as in our case), i.e., no chipboards or similar underneath, it should be at least 25 mm thick but no more than 30 mm. This is according to both Siljan and Dala Floda Golv.
We have at least 25x158 mm pine flooring on underfloor heating. The floor comes from Siljan and according to them, it works excellently on underfloor heating. The boards are milled on the underside, which I've heard is supposed to prevent the boards from warping/twisting.
If the floor is to serve as a load-bearing structure directly on the joists (as in our case), i.e., no chipboards or similar underneath, it should be at least 25 mm thick but no more than 30 mm. This is according to both Siljan and Dala Floda Golv.
30mm wood above underfloor heating is completely unsuitable. 25mm is borderline. 20mm is okay.
If you have a heating system with only underfloor heating, it's a disaster to lay such a thick floor because you have to raise the supply temperature just to handle the heat requirement in the wood-floored room. If you have a mixed system with both old high-temperature radiators and underfloor heating, it matters a little less, but it's still a waste to have such a thick floor.
If you have a heating system with only underfloor heating, it's a disaster to lay such a thick floor because you have to raise the supply temperature just to handle the heat requirement in the wood-floored room. If you have a mixed system with both old high-temperature radiators and underfloor heating, it matters a little less, but it's still a waste to have such a thick floor.
Hmmm, that's often mentioned on the forum and elsewhere... But surely it must also be affected by what you have underneath (the energy you put under the floorboards must go somewhere, right?). If you have good insulation and convector plates (like Wirsbo's floor cassette), then it should work quite well with a rather "thick" wooden floor, right?MathiasS said:
...or does it just get warm in the space between the subfloor/insulation and the planks? :-/
JoGi
MattiasS->
You seem very sure of yourself. Personal experience or where did you get the information from?
So you mean that 20 mm is sufficient as a load-bearing structure directly on the floor joists? According to the flooring manufacturers we've spoken with, it's not.
Then you shouldn’t be able to lay 22 mm chipboard on underfloor heating either? Or does chipboard conduct heat better than a wooden floor? If you lay chipboard, you end up even higher above the underfloor heating since the floor also adds some height, whether you choose laminate or parquet flooring, right?
I'm not talking about underfloor heating embedded in a concrete slab, but rather underfloor heating in a wooden joist system with a crawl space underneath. If the underfloor heating is embedded in the slab, then the floor ends up further from the pipes than when, as in our case, the underfloor heating pipes are lying in plates between the floor joists.
Well... soon we'll see if we're heating for the crows...
You seem very sure of yourself. Personal experience or where did you get the information from?
So you mean that 20 mm is sufficient as a load-bearing structure directly on the floor joists? According to the flooring manufacturers we've spoken with, it's not.
Then you shouldn’t be able to lay 22 mm chipboard on underfloor heating either? Or does chipboard conduct heat better than a wooden floor? If you lay chipboard, you end up even higher above the underfloor heating since the floor also adds some height, whether you choose laminate or parquet flooring, right?
I'm not talking about underfloor heating embedded in a concrete slab, but rather underfloor heating in a wooden joist system with a crawl space underneath. If the underfloor heating is embedded in the slab, then the floor ends up further from the pipes than when, as in our case, the underfloor heating pipes are lying in plates between the floor joists.
Well... soon we'll see if we're heating for the crows...
We are talking about two things:
1. How thick a floor is required to support weight.
2. How thick a floor is suitable to lay above underfloor heating.
These two things do not always match.
I'm not saying that a 20mm floor is sufficient for all wooden joists; however, I'm saying it is inadvisable to lay a floor thicker than that above underfloor heating.
Somewhere, I have a clever Excel sheet that calculates a bit on these things. I'll see if I can find it and do a couple of "simulations."
Marge, call a few underfloor heating suppliers and see what they think about 25-30mm wooden floors above the pipes!!! Sometimes you may have no choice, but if it can be avoided then...
Best regards,
Mathias
1. How thick a floor is required to support weight.
2. How thick a floor is suitable to lay above underfloor heating.
These two things do not always match.
I'm not saying that a 20mm floor is sufficient for all wooden joists; however, I'm saying it is inadvisable to lay a floor thicker than that above underfloor heating.
Somewhere, I have a clever Excel sheet that calculates a bit on these things. I'll see if I can find it and do a couple of "simulations."
Marge, call a few underfloor heating suppliers and see what they think about 25-30mm wooden floors above the pipes!!! Sometimes you may have no choice, but if it can be avoided then...
Best regards,
Mathias
Some calculated half-truths:
For any underfloor heating system where we only change the surface layer, the following applies:
With tiles, a supply temperature of 34 degrees is required.
With 28mm wooden flooring, a supply temperature of just over 45 degrees is required.
18mm wooden flooring falls somewhere in between.
What I am trying to say is that given a heat pump, these differences in supply temperature have a relatively large impact on the pump's efficiency (burning money).
Particleboard is not as thermally inert as wood (not as dense), but underfloor heating systems with particleboard and double gypsum above the pipes are nothing to cheer about either...
For any underfloor heating system where we only change the surface layer, the following applies:
With tiles, a supply temperature of 34 degrees is required.
With 28mm wooden flooring, a supply temperature of just over 45 degrees is required.
18mm wooden flooring falls somewhere in between.
What I am trying to say is that given a heat pump, these differences in supply temperature have a relatively large impact on the pump's efficiency (burning money).
Particleboard is not as thermally inert as wood (not as dense), but underfloor heating systems with particleboard and double gypsum above the pipes are nothing to cheer about either...
Gypsum conducts heat relatively well, so it's not a major problem. The reason chipboard conducts heat slightly better than wood is that the chipboard is much denser in material, i.e., it contains less air than solid wood. Air insulates very well.
To reduce the total thickness over the underfloor heating pipes, you can lay chipboard at the bottom, nailing/screwing it to the joists. Then you lay sparse paneling, e.g., regular 22x95 tongue and groove boards, as supports for the heat plates. On top of this, you lay your flooring and it should work well with a maximum of 30 mm solid wood according to several manufacturers. As Mathias writes, thicker flooring requires a higher water temperature in the pipes, but it also depends on how warm you want the floors.
A friend of mine has 22 mm chipboard + 15 mm parquet over his pipes, and it works well.
Note that you must have at least 15 mm parquet on the sparse paneling for it to work, thinner parquet will probably flex. We will use 15 mm parquet in some places and solid 25 mm pine flooring in others, I'm not daring to go thinner.
To reduce the total thickness over the underfloor heating pipes, you can lay chipboard at the bottom, nailing/screwing it to the joists. Then you lay sparse paneling, e.g., regular 22x95 tongue and groove boards, as supports for the heat plates. On top of this, you lay your flooring and it should work well with a maximum of 30 mm solid wood according to several manufacturers. As Mathias writes, thicker flooring requires a higher water temperature in the pipes, but it also depends on how warm you want the floors.
A friend of mine has 22 mm chipboard + 15 mm parquet over his pipes, and it works well.
Note that you must have at least 15 mm parquet on the sparse paneling for it to work, thinner parquet will probably flex. We will use 15 mm parquet in some places and solid 25 mm pine flooring in others, I'm not daring to go thinner.
Of course, it *CAN* be used, the question is how optimally the system functions.marge said:
I solved the problem myself by placing the pipes in spaced panels on the beams, and then adding 20mm wood on top of this. I could have used 15-16mm too, but wanted a few extra millimeters to be able to sand the floor if needed.
Result:
1. Underfloor heating works well
2. The floor is sturdy.
DESPITE this, the room with wood flooring will be the "determining" one for the supply temperature that the VP must produce => just because I want wooden floors, the pump has to work in a less efficient operating range => poorer operational economy. Thicker flooring would have resulted in an additional 5-7 degrees higher supply temperature and even worse efficiency as a result.
Well, we've already covered 140 sqm of the house in this way, so, as I mentioned earlier, we'll just have to wait and see if we're just "heating for the birds" (haven't installed the pump yet).
Strange that the HVAC engineer who calculated the power requirements, etc., didn't comment on our choice of 25 mm wood flooring, he should have if it reduces the efficiency as much as you say. Anyway, what's done is done. ;D
Strange that the HVAC engineer who calculated the power requirements, etc., didn't comment on our choice of 25 mm wood flooring, he should have if it reduces the efficiency as much as you say. Anyway, what's done is done. ;D
A summary could be:
1.) Too wide floors can cause warping
2.) Too deep floors provide poorer thermal conductivity and can lead to the heat not coming through?
Is that correct?
A final question, does scoring the underside of the board prevent warping? Could one have up to 250 mm wide in that case? Say yes
Best regards,
David
1.) Too wide floors can cause warping
2.) Too deep floors provide poorer thermal conductivity and can lead to the heat not coming through?
Is that correct?
A final question, does scoring the underside of the board prevent warping? Could one have up to 250 mm wide in that case? Say yes
Best regards,
David
Real floorboards SHOULD be grooved on the underside to prevent the board from warping.
A wider plank has more built-in movement allowance than a narrower one. If it's screwed along both sides, you have built in the possibility for it to bow in the middle if laid when it's very dry. When the humidity increases, it starts to swell, and if it's tight at the edges, it can rise in the middle.
Conversely, you may get slightly larger gaps between the planks when it's dry outside if you lay the floor when it's extremely humid, like during a rainy fall.
It's probably not a problem in a house that's always heated and maintains a fairly consistent humidity level; it's worse in a summer cottage with large temperature and humidity changes.
Enough of the scare tactics, I think it will work just fine, but check with some experienced floor manufacturers like Dala Floda and MörkaSkog or whatever they're called, they should know.
I hope they say OK because it will look really great with such wide planks!
A wider plank has more built-in movement allowance than a narrower one. If it's screwed along both sides, you have built in the possibility for it to bow in the middle if laid when it's very dry. When the humidity increases, it starts to swell, and if it's tight at the edges, it can rise in the middle.
Conversely, you may get slightly larger gaps between the planks when it's dry outside if you lay the floor when it's extremely humid, like during a rainy fall.
It's probably not a problem in a house that's always heated and maintains a fairly consistent humidity level; it's worse in a summer cottage with large temperature and humidity changes.
Enough of the scare tactics, I think it will work just fine, but check with some experienced floor manufacturers like Dala Floda and MörkaSkog or whatever they're called, they should know.
I hope they say OK because it will look really great with such wide planks!