This study examines the stocks of building materials in Toronto’s in-use and annual obsolete single detached housing, to provide potential environmental benefit parameters for city scale material reuse and recycling. The material volumes of five archetypes, developed to represent typical Toronto housing, were measured and extrapolated to the city scale. Applying established criteria for reusability and recyclability, city scale reusable and recyclable stocks were determined for three environmental indicators: material volume headed to landfill, carbon dioxide emissions, and primary energy consumption. It was determined that 61-66% of the material volume in Toronto’s in-use and annual obsolete housing could be reclaimed for reuse/recycling, and was mostly composed of masonry, concrete, and framing lumber from houses built from 1930-1960. Additionally, annual obsolete reusable materials represented an embodied carbon of 2,287-4,116 tonnes and energy of 52,883-95,189 GJ. By addressing common barriers to widespread uptake of reuse/recycling, Toronto could reap these determined potential environmental benefits.