The Ontario Building Code | Cantilevered Floor Joists
9.23.9.9. Cantilevered floor joists
(1) floor joists supporting roof loads shall not be cantilevered more than 400 mm beyond their supports where 38 mm by 184 mm joists are used and not more than 600 mm beyond their supports where 38 mm by 235 mm or larger joists are used.
(2) The cantilevered portions referred to in Sentence (1) shall not support floor loads from other storeys unless calculations are provided to show that the design resistances of the cantilevered joists are not exceeded.
(3) Where cantilevered floor joists described in Sentences (1) and (2) are at right angles to the main floor joists, the tail joists in the cantilevered portion shall,
(a) extend inward away from the cantilever support a distance equal to not less than six times the length of the cantilever, and
(b) shall be end nailed to an interior doubled header joist in conformance with Table 9.23.3.4.
In Plain Language
Cantilevered floor joists, which extend beyond their support to create an overhang, must meet the specific requirements set out in this article.
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.