The Ontario Building Code | Minimum Fire-Resistance Rating
3.1.7.4. Minimum Fire-Resistance Rating
(1) The use of materials or assemblies having a greater fire-resistance rating than required shall impose no obligation to exceed in whole or in part the minimumfire-resistance ratings required by this Part.
In Plain Language
Using a higher fire-resistance rating than the Code requires is always allowed and creates no obligation to also upgrade other parts of the assembly to match that higher rating.
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.