UFH , detail at base of stud wall

[Jilly]

We have an old concrete slab,  and hope to have UFH. The ex builder placed stud walls onto the floor, sitting on DPM (after initially saying they would lay it onto a brick course). If the visible DPM plus another on the floor in each room is lapped up the walls, it will encase the bottom part of the timber wall in plastic. Will that be ok? It seems to me it will get condensation and rot the wood at the bottom?

 

Said builder will never come back to rectify (I have waited 6 months for other bits and given up). 

 

Thank you!

[markc]

When you say an old concrete slab, how old? is it insulated? UFH and old floors are not a good combination.

[Dudda]

From looking at the photo I've made some assumptions. The existing slab is old and not insulated but dry so probably has a layer of plastic under it. Maybe 70's or 80's? The door looks to be circa 150mm above this slab. You're probably planning on putting down 100mm of insulation and then 50mm liquid screed with UFH pipes. The timber stud walls therefore will be touching the cold concrete and not insulated where you're worried about the condensation. Ideally these studs would be built on top of a thermal block. I don't think I'd be worried as you're limited to the 100mm or whatever amount of insulation you can fit is and won't have a lot of air circulation within the stud wall so little chance of vapor which can condense.

[Jilly]

7 hours ago, Dudda said:

From looking at the photo I've made some assumptions. The existing slab is old and not insulated but dry so probably has a layer of plastic under it. Maybe 70's or 80's? The door looks to be circa 150mm above this slab. You're probably planning on putting down 100mm of insulation and then 50mm liquid screed with UFH pipes. The timber stud walls therefore will be touching the cold concrete and not insulated where you're worried about the condensation. Ideally these studs would be built on top of a thermal block. I don't think I'd be worried as you're limited to the 100mm or whatever amount of insulation you can fit is and won't have a lot of air circulation within the stud wall so little chance of vapor which can condense.

Hi Dudda, yes, all your assumptions are exactly right. Thank you for your reassurance, I was worried it would be a pain to rectify now. 

[Jilly]

Just had a plumber come to quote for UFH and he isn't keen on this at all,  he'd like to change it for a masonry layer.

[Cpd]

I can’t see how changing it to masonry would be better as the timber will have more insulation quality’s than masonry and be less likely to attract condensation…. (I think…..) 
if the timber stud walls are not structural then they should not have been built until the floors were finished (I think……) that way there would have been insulation under them already. 

[Jilly]

?I know, the builder has done so many odd things. We have parted ways..

[Russell griffiths]

That’s a fairly standard way of doing the walls by many timberframe companies. 

I wouldn’t worry too much.