The Ontario Building Code | Vent Pipe Flashing
(1) Flashing fabricated on site for vent pipesshall be fabricated from,
(a) copper sheet at least 0.33 mm thick,
(b) aluminum sheet at least 0.48 mm thick,
(c) alloyed zinc sheet at least 0.35 mm thick,
(d) lead sheet at least 1.73 mm thick,
(e) galvanized steel sheet at least 0.33 mm thick, or
(f) polychloroprene (neoprene) at least 2.89 mm thick.
(2) Prefabricated flashing for vent pipesshall be certified to CSA B272, "Prefabricated Self-Sealing Roof vent Flashings".