The Ontario Building Code | Heavy Roofing Materials
9.23.4.5. Heavy Roofing Materials
(1) Where a roof is required to support an additional uniform dead load from roofing materials such as concrete roofing tile, or materials other than as specified in Section 9.26., such as clay roofing tiles, the additional load shall be allowed for by reducing,
(a) the spans for roof joists and rafters in Tables A-4 to A-7, or the spacing of the members, and
(b) the spans for ridge beams and lintels in Tables A-12 to A-16.
9.23.5. Notching and Drilling
In Plain Language
Heavy roofing materials, such as tile or slate, require specific structural consideration as set out in this article, since these materials weigh considerably more than standard asphalt shingles.
This is a plain-language summary of the 2012/2017 Ontario Building Code text above, for general understanding only and not a substitute for the Code. Always confirm current requirements against the 2024 edition (O.Reg. 163/24) or a qualified professional before construction.