The Ontario Building Code | Reduction in Thickness of Fire Separation by Beams and Joists
9.10.9.9. Reduction in Thickness of Fire Separation by Beams and joists
(1) Where pockets for the support of beams or joists are formed in a masonry or concrete fire separation, the remaining total thickness of solid masonry and/or grout and/or concrete shall be not less than the required equivalent thickness shown for Type S monolithic concrete in Table 2.1.1. of MMAH Supplementary Standard SB-2, "Fire Performance Ratings", for the required fire-resistance rating.
In Plain Language
Beams and joists can reduce the effective thickness of a fire separation at the point they pass through it, and this article sets out how that reduction must be accounted for.
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.