Ufh subfloor

[damessiahuk]

I'm just exploring installing UFH in a suspended joist G/f.

The plan at this stage is to PIR insulate between joists, lay pipes, then screed over.

I am now unsure what to do next....

I would like a wood floor (real or fake!).

Does one put down the original T&G floorboards and sand/seal? Or do I need to put something that's better to conduct UFH (eg tiles or lvt)

If the latter, do the T&G stay there or do they just come up and replaced with Ply/tile board and add the flooring. My concern was if the TG didn't come up, there would be quite a few layers between the pipes and the floor.

I can't find any clear guidance on what subfloor should be.

 

[Madrab]

The plan at this stage is to PIR insulate between joists, lay pipes, then screed over.

You wouldn't usually use a wet screed in that type of floating floor UFH implementation, rather what's called a biscuit mix, either that or use spreader plates. Then the floor covering can be laid directly down on top of that.

Floor gets lifted - lower support batons (and sometimes ply) nailed to the joists - PIR then laid onto that - then the UFH pipework clipped to that with a biscuit mix added as a thermal mass or pipe directly into metal spreader plates tacked to the joists. Then the floor covering.

 

[damessiahuk]

Thanks. I did mean biscuit mix.

So you wouldn't put t&G back down, just lay the new flooring on top of joists and screed (with some ply or similar in-between?)

 

[damessiahuk]

What if I just put t and G back down, and varnished? Does that work with UFH or is it too thick?

 

[Madrab]

What if I just put t and G back down, and varnished? Does that work with UFH or is it too thick?

No, not too thick, would need to be in good condition though and well fitted.