The Ontario Building Code | Notching of Framing Members
9.23.5.2. Notching of Framing Members
(1) floor, roof and ceiling framing members are permitted to be notched provided the notch is located on the top of the member within half the joist depth from the edge of bearing and is not deeper than one-third the joist depth, unless the depth of the member is increased by the size of the notch.
In Plain Language
Notching of framing members is limited as set out in this article, similar in purpose to the hole-drilling limits but addressing cuts made into the edge of a member.
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.