Sheet Metal Leaders (1) A sheet metal leader shall not be used except above ground outside a building. Article 7.2.6.9. Ontario Regulation 332/12 Building Code, O. Reg. 332/12: BUILDING CODE (ontario.ca) © Queen’s Printer for Ontario, 2021. Similar articles Conformance to Standards Plumbing Basement Drainage Planning Fittings Restricted in Use Threaded Cast Iron Drainage Fittings