9. Insulation applied to the exterior of a basement foundation wall or to the exterior of a slab-on-ground floor must extend down to at least 600 mm below exterior ground level.
However, in the case of a slab-on-ground floor without a foundation wall, the insulation may extend down and outward from the floor over a total distance of at least 600 mm measured from the finished ground level.
O.C. 89-83, s. 9; O.C. 1721-85, s. 3.