DIY Doctor

Best Product to Fill Gaps in Cavity Wall Insualtion

Postby SteveSpits » Mon Nov 27, 2017 6:12 am


Currently renovating a 70’s build that already has Cavity insualtion. It appears to be polystyrene, white and very crumbly, but dry and in good nick from bits i’ve seen.

During renovations some of this insulation has fallen out.... where I have the end of an RSJ perpendicular to Cavity wall and sitting on inner leaf, and block work around it....where old extractor vents have been removed etc.

My question is this, what is best way/meterial to fill these gaps I have created to prevent cold spots. Should I chuck a load of the loose insulation beads in? Can I use an insulation type expanding foam, and squirt it in and let it fill gaps. Or possibly a combination of the two.


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