The Ontario Building Code | Intersection of Built-Up Roofs and Masonry
220.127.116.11. Intersection of Built-Up Roofs and masonry
(1) The intersection of built-up roofs with masonry walls or chimneysshall have a cant strip at the intersection and a roofing membrane shall be mopped over the cant strip and not less than 150 mm up the wall.
(2) Counter flashing installed over the intersection referred to in Sentence (1) shall be embedded not less than 25 mm in the masonry, and shall be of sufficient length to extend down not less than 150 mm, lapping the membrane on the masonry not less than 100 mm.