Travis Johnson wrote:I always thought papercrete would work. You could pour it in 4x8 sheets and then apply it to the walls. The R-Factor is not that high, but it would be enough to break the thermal bridge.
Alex Klohe wrote:We used Rock Wool Comfort Board 80.
It's basalt rock made into 2x4 rigid panels and at 1.5 inches thick it gives you an R6.
It's designed for underground exterior use.
You can get through Lowes or Home Despot but you have to order a whole pallet.