Wing Insulation for Frost-Protected Shallow Foundation
Beginning construction of a two story garage/home office, with 600 SF apartment above. (Plans for permitting go to the city early next week).
I’m going with a shallow frost protected foundation. For my area (air freezing index=960) horizontal wing insulation isn’t required, but I’m wondering if it’s a good idea anyway. Maybe 2″ of Type II EPS, extending 12″ at perimeter and 24″ at corners?
Vertical and under-slab insulation is 4″ of Type II EPS. Building is planned to be net-zero energy, with r-40 walls, r-60 roof, and 3000-4000 W of south-facing PV panels. Site is flat.
Given the high cost of building materials, I’d like to save money where I can, but obviously not at the expense of performance or durability.
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