I’ve written about sub-slab insulation and heated floors several times over the past couple years, this post is about something I’ve been thinking about for a while now, using a fibrous insulation, like Rockwool’s ComfortBoard 80 or 110 under a concrete slab with hot water heat. The questions I had about this strategy are one, will there be an issue with compression of the insulation when concrete is poured over the product? And two, will a staple be able to hold the hot water tubing in place?
Rockwool ComfortBoard being installed below a concrete slab. Photo by Travis Brungardt