[Greenbuilding] frozen ground

[Clarke Olsen]

Here's my question: we have leveled out and compacted the sand/gravel grade for a 4" slab, but the ground is frozen, maybe 4". Should we put down our 4" of ridge foam, and presume that it will thaw from below, shielded from the surface cold, or leave it uncovered, and try to thaw it from above before putting down foam? This is inside a drafty, unheated but enclosed room.

Clarke Olsen
373 route 203
Spencertown, NY 12165 
USA
518-392-4640
colsen at fairpoint.net