Underfloor heating and flooring for tiling

[Alwyn]

Hi,
I'm working on an old house with suspended floors on the ground floor. As we wanted to insulate the floor we decided to put in wet UFH as well.
So we've lifted the boards, used them as battens screwed underneath the joists to hold 3 inches of insulation, Wet UFH pipes and a nearly dry screed mix- about an inch - the joists were 4" thick, and I'm waiting for the screed to go off...

Now i'm planning the flooring to put on top. I've considered putting 18mm ply down and then tiling on top of that, but I'm worried that the ply will be too good an insulator and we'll never see the benefit of the UFH.

I've read that green chipboard would be cheaper than ply and also better for the UFH, but i've also read that tiling on this is not ideal.

Has anyone got any experience of this and can help me with the flooring solution??

Helpp!!

 

[Mike]

i've never heard or seen it done like that but it'll be interesting to hear what the solution will be

 

[White Room]

You say suspended floor, it sounds like just a joisted floor, how many m2 floor area are we talking here.

 

[Alwyn]

Hi,

Yes sorry I meant joisted floor.....the whole floor is about 40sqm, but the kitchen floor which the wife wants tiled is about 20sqm

 

[White Room]

I take it theres no deflection on the floor, use ply, you don't mention what tiles your fixing.

 

[Alwyn]

Hi, no there will be no deflection with the ply but do you think the ply will stop the heat coming through? Im hopefully going to use natural slate to tile.

 

[White Room]

I found that wood is very good for heat transfer, there maybe other replies so pop back tomorrow.

 

[Alwyn]

Can anyone else confirm that putting ply flooring down on the UFH and then tiling on top will not stop the heat coming through?

 

[Alwyn]

Help!!

 

[Barry bp]

A decoupling mat would let heat trnsfer quicker

 

[doug boardley]

A decoupling mat would let heat trnsfer quicker

how???

 

[doug boardley]

ply with a hardiebacker 250, and a decoupling mat, would be my way to go. There may be an initial lag in warm up time, but as long as your floor is free from deflection it's a price worth paying imo

 

[Ajax123]

I have done a similar thing in my house but the floors do not get very warm cos you are right the wooden floors are a good insulator. Have you looked at something like the Celecta Screed Board which is a gypsum based board which is a good conductor.

Another option I have seen used is a metal diffuser plate rather than timber boards. Alluminium is good for this.