We are building a slab on grade addition to our house in Wisconsin, zone 6. It has a frost footing and wall which will be back- filled with sand. To match the aesthetics of the existing house, the exposed foundation will be rock faced cement block, with 4 inches of foam on the inside wall of the foundation (and 4″ under slab and @ slab edges).

The WI code requires waterproofing of the frost wall. Our mason with 50 years experience doesn’t think it is necessary, but the inspector does, so I’ll seal it. I thought I’d use an acrylic product.

Any thoughts and recommendations?