Rockwool & sleepers
Over our concrete slab we’ve installed 2 x 4 sleepers with Rockwool® ComfortBoard80 in between. Total slab is R-30.
This is our 3/4” plywood subloor air-sealed with Siga Wigluv tape.
Insulated slab foundation detail
This is a technical detail for the hyper-insulated slab foundation we built. It was designed using energy software for our climate and is somewhat atypical. Ours is foam-free but you can read about a similar idea in the article Insulating Over a Structural Slab in the Journal of Light Frame Construction.