Insulation on interior or exterior of frost wall - or both - for floating slab?
...insulation you can eliminate the need to get below the frostline. By insulating the perimeter you are in effect just moving the frostline to 4 inches deep rather than 4 feet. One foot of dirt insulates about the same as one inch of foam.
However you build it and insulate it, one of the most glaring oversights in founda...