Tiling over wet UFH between joists

[CJ]

In an ideal world, something like the structural Hardifloor would be perfect as it offers high thermal conductivity with minimal thermal resistance and is also fairly stable with regards to expansion and contraction - So perfect to tile.

Structural bases made out of timber work well too - but as Chalker said it does take longer for the heat to come through initially because the wood does have a higher R value than something like fermacell - but because of this it retains heat into the room better once it is in.

Again, as Chalker has said the pipe is essentially a heating element but because of thermal bridging it will do very little to warm the space without a means of spreading the heat over the whole floor. Don't even think about trying to run the system without the use of a heat diffuser "spreader" plate or (provided the joists are strong enough to take the weight) a screed over the pipes between the joists.

Whichever, install method / material is chosen for the UFH I would advocate a decoupler on top as a matter of course because we all know how fragile any natural stone can be... At least if there is a membrane present the tiler has done everything in their power to protect the top layer.

Thanx for that David.

Have been looking at Hardifloor, but at 37mm thick, plus membrane, and tile, that will raise the floor by quite a horrendous amount. Poss 52mm? Wot else do you suggest?

 

[J Sid]

Thanx for that David.

Have been looking at Hardifloor, but at 37mm thick, plus membrane, and tile, that will raise the floor by quite a horrendous amount. Poss 52mm? Wot else do you suggest?

thought in came in 19mm or 22mm , no?

 

[Old Mod]

It does Julian.

 

[CJ]

Slight size typo........not sure which bit I read.

 

[Dannym80]

HardiFloor is the best way to go, no expansion or flex issues that you'd have with ply as its far more stable. As some have already said, its thermal conductivity is better than ply also. It does come in 19mm or 22 mm so height shouldn't be an issue. With marble going down I personally would fit ditra or durabase everytime over any ufh.