The Ontario Building Code | Loads Due to Use of Floors and Roofs
4.1.5.1. Loads Due to Use of floors and Roofs
(1) Except as provided in Sentence (2), the specified live loadon an area of floor or roof depends on the intended use and occupancy, and shall not be less than whichever of the following loads produces the most critical effect:
(a) the uniformly distributed load patterns listed in Article 4.1.5.3.,
(b) the loads due to the intended use andoccupancy, or
(c) the concentrated loads listed in Article 4.1.5.9.
(2) For buildings in the Low Importance Category as described in Table 4.1.2.1.B., a factor of 0.8 may be applied to the live load.
In Plain Language
Except where otherwise specified, the live load a floor or roof must be designed for depends on how that area is actually used, since an area used for storage needs a very different load capacity than one used as a quiet office.
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.