1507.9.9 Flashing.
BC § 1507.9.9
At the juncture of the roof and vertical surfaces, flashing and counterflashing shall be provided in accordance with the manufacturer's instructions, and where of metal, shall be not less than 0.019-inch (0.48 mm) (No. 26 galvanized sheet gage) corrosion-resistant metal. The valley flashing shall extend at least 11 inches (279 mm) from the centerline each way and have a splash diverter rib not less than 1 inch (25.4 mm) high at the flow line formed as part of the flashing. Sections of flashing shall have an end lap of not less than 4 inches (101.6 mm). For roof slopes of three units vertical in 12 units horizontal (25-percent slope) and over, the valley flashing shall have a 36-inch (914.4 mm) wide underlayment of either one layer of Type I underlayment running the full length of the valley or a self-adhering polymer-modified bitumen sheet complying with ASTM D 1970, in addition to other required underlayment. For slopes under seven units vertical in 12 units horizontal (58-percent slope) the metal valley flashing underlayment shall be solidly cemented to the roofing underlayment or a self-adhering polymer-modified bitumen sheet shall be installed. Editor's note: For related unconsolidated provisions, see Appendix A at L.L. 2014/051.
