jklingel
Well-known member
Here is the deal: Under a SOG, it seems builders in most colder places typically use about 2" of XPS, and run it either right up to the foundation wall, or leave a gap to let heat out of the building and down to the footer. My engineer recommends a 16" gap. The foundation wall will be 12" ICFs down 4' (to the TOP of the footer), with an additional 2" of XPS on the outside, down 2', to protect the end of the slab, etc. Being obsessed w/ insulation, the thought of planning in heat loss is hard to take, though I understand the reasoning. It seems that different engineers have different opinions on this, so I thought I'd ask what others have heard, or have done and survived. Bear in mind that this is a high degree day area. The code for footer depth is 40" from grade to the bottom of the footer. So, to gap or not to gap the XPS? Thanks. j