SBS 11.3.2.2-1 Cast Iron Drains

(1) Gypsum Deck Overlay: If required by design authority.
(2) Vapour Retarder: If required by design authority.
(3) Insulation: Mechanically fastened. See available insulation products in the Accepted Materials section of this Manual.
(4) Insulation Overlay Board: Asphalt adhered or mechanically fastened. Two layers required over heat-sensitive insulation.
(5) Primary Membrane and Membrane Protection
(6) Mastic: As approved by manufacturer.
(7) Base Sheet Flashing: As approved by membrane manufacturer (See (C) below).

(A) Acceptable Deck
(B) Roof Drain Assembly
(C) Lead Flashing: Minimum 15 kg / m² (3 lb / ft²) weight lead sheet; flange extending minimum 25 mm (1") into bowl to 150 mm (6") beyond perimeter of drain; embed in mastic (6) and prime top surface where required by manufacturer or minimum 1 m x 1 m (39" x 39") 3 mm thick modified bituminous base sheet; to be supplied by trade supplying roof drain. For asphalt and gravel built-up systems only.

NOTE: Refer to RGC Guarantee Standards for additional requirements.

Leader size is determined by using the calculation found in the BC Building Code at Appendix P.7.4.10 and Section 7.4.10.11 (Section 7.4.10.10 for gutters)(current edition) in conjunction with the 15-minute rainfall value from the National Building Code, Appendix C.