Slab on grade foundation with 12” grade beam around perimeter and under interior bearing walls, compacted sand fill under 2” foam insulation. This site had a high water table and granite close to the surface preventing a conventional foundation. 2” foam insulation was laid horizontally around the perimeter to further frost proof and insulate the structural slab.
Radon mitigation barrier consists of 4” perforated drain tile run inside the perimeter walls. This pipe is connected to a sealed sump and the entire grid of pipe is covered with pea gravel. 2” foam and vapor barrier complete the below slab work. The vent pipe from the sump is later run up through the roof, creating a stack effect to vent radon gas to the outside.