PEX under screed

[baker332]

Hi,

I'm running 15mm PEX pipe under the screed circa 35-40mm in depth, the pipes are laid on a concrete sub base that has 150mm insulation in. My question is what is the best insulation to wrap the pipes in? I'm currently using wool, but is there anything with more performance? Should it even matter?

Pipe run is 3m out and 3m return total 6m will be in the screed without any joins all one run in pex.

Thanks

 

[Madrab]

Is this a wind up? You don't insulate any of the pipe in the screed. Also, that's a very shallow screed, 50mm would be the usual starting point with a liquid screed, more for a hand mixed.

 

[baker332]

Is this a wind up? You don't insulate any of the pipe in the screed. Also, that's a very shallow screed, 50mm would be the usual starting point with a liquid screed, more for a hand mixed.

Not a wind up - How am I suppose to know if insulation is required or not, it seems some people do and others don't/

Just wondering what is best practice for this type of thing.

The pipe is not underfloor heating, it's to a radiator.

 

[Madrab]

Oh I see, apologies. When someone mentions PEX pipe in screed then it's is usually to do with UFH.

You would want as much insulation as you can get on it, the screed/concrete will draw heat out of the pipework in no time and heat its surrounding concrete so the floor would end up becoming a thermal soak. Min insulation would be ~13mm walled, so that would give a total of 41mm dia.

You could wrap in wool hair felt but not sure how effective it would be encased in screed as it would probably tend to soak up the screed mix.

 

[baker332]

Oh I see, apologies. When someone mentions PEX pipe in screed then it's is usually to do with UFH.

You would want as much insulation as you can get on it, the screed/concrete will draw heat out of the pipework in no time and heat its surrounding concrete so the floor would end up becoming a thermal soak. Min insulation would be ~13mm walled, so that would give a total of 41mm dia.

You could wrap in wool hair felt but not sure how effective it would be encased in screed as it would probably tend to soak up the screed mix.

Thanks - that is essentially what I've done but had this exact realisation, that the wool will just soak up the screed. I'll look into something thicker then and possibly create a channel into the concrete to ensure thicker insulation.

 

[Madrab]

Thanks - that is essentially what I've done but had this exact realisation, that the wool will just soak up the screed. I'll look into something thicker then and possibly create a channel into the concrete to ensure thicker insulation.

The min, as suggested would be the normal foam insulation you get in say screwfix (13mm) etc and tape up the joins with good quality duct tape, that should make it fluid proof.