underfloor insulation

[marcusc]

Hello! We have a georgian G2 property and have currently got the floorboards up in a ground floor room, so are taking the opportunity to install some insulation. Our builder was just going to put 100mm celotex in, but I was wanting to use vapour barriers and indinature hemp or sheepswool. The advice out in the internet is varying, have any of you got any thoughts or real life experience of an install, or advice. I have had a trawl through the archives and I can't seem to find anything here. The floor has plenty of clear air underneath the joists, and it goes down to bare earth, with functioning air bricks along the external wall of the room. any thoughts appreciated, cheers, Marcus.

 

[paulc]

The foil facing of Celotex will act as a VCM, and you can apply aluminium tape across the joists. As long as you don't compromise air flow across any dwarf walls, the Celotex shouldn't cause any issues. Just make sure any gaps between joists & walls are filled with expanding foam or Gapotape.

 

[mh12]

Hello! We have a georgian G2 property and have currently got the floorboards up in a ground floor room, so are taking the opportunity to install some insulation. Our builder was just going to put 100mm celotex in, but I was wanting to use vapour barriers and indinature hemp or sheepswool. The advice out in the internet is varying, have any of you got any thoughts or real life experience of an install, or advice. I have had a trawl through the archives and I can't seem to find anything here. The floor has plenty of clear air underneath the joists, and it goes down to bare earth, with functioning air bricks along the external wall of the room. any thoughts appreciated, cheers, Marcus.

A Best Practice Approach To Insulating Suspended Timber Floors

Fintan from our Technical Team discusses the thermal loss issues associated with suspended timber floors and outlines a best practice approach to tackling them.

www.ecologicalbuildingsystems.com

Although I have no direct experience in this matter yet I will be following the above guidance when I get round to it.

I think breathable is the way to go.

 

[larry]

As much as anything celotex is very hard to cut accurately, particularly for irregular edged and angled old joists. The small gaps around the edges can, I understand, then significantly compromise the insulation effectiveness and create cold spots. We used 100mm rockwool with a roofing breathable membrane laid up and over the joists for it to sit in it has made a big difference.