The Ontario Building Code | Required Waterproofing Required waterproofing

(1) Where hydrostatic pressure occurs, waterproofing is required for exterior surfaces of,

(a) floors-on-ground, and

(b) below ground walls, where the exterior finished ground level is at a higher elevation than the ground level inside the foundation walls.

(2) Roofs of underground structures shall be waterproofed to prevent the entry of water into the structure.