The Ontario Building Code | Combustible Projections
184.108.40.206. Combustible Projections
(1) Except for a building containing one or two dwelling units only, combustibleprojections on the exterior of a wall that could expose an adjacent building to fire spread and are more than 1 m above ground level, including balconies, platforms, canopiesand stairs, shall not be permitted within,
(a) 1.2 m of a property line or the centre line of a public way, or
(b) 2.4 m of a combustibleprojection on another building on the same property.
(2) Where the exposing building face has a limiting distance of not more than 0.45 m, projecting roof soffits shall not be constructed above the exposing building face.
(3) Where the exposing building face has a limiting distance of more than 0.45 m, the face of roof soffits above the exposing building face shall not project to less than 0.45 m from the property line.
(4) Where roof soffits project to less than 1.2 m from the centre line of a lane or public thoroughfare or from an imaginary line between two buildings or fire compartmentson the same property, they shall,
(a) have no openings, and
(b) be protected by,
(i) not less than 0.38 mm thick sheet steel,
(ii) unvented aluminum conforming to CAN/CGSB-93.2-M, "Prefinished Aluminum Siding, Soffits and Fascia, for Residential Use",
(iii) not less than 12.7 mm thick gypsum soffit board or gypsum ceiling board installed according to CSA A82.31-M, "Gypsum Board Application",
(iv) not less than 11 mm thick plywood,
(v) not less than 12.5 mm thick OSB or waferboard, or
(vi) not less than 11 mm thick lumber.
(5) For buildings of combustible construction, materials installed to provide the required protection of soffits may be covered with a combustible or noncombustible finish material.