The Ontario Building Code | Combustible Mezzanines
3.1.5.24. Combustible Mezzanines
(1) In a building required to be of noncombustible construction, a mezzaninelocated within a live/work unit is permitted to be of combustible construction, provided the area of the mezzanine is not more than 25% of the floor area of the live/work unitor 20 m2, whichever is less, and has no obstructions more than 1 070 mm above the floor.
In Plain Language
A mezzanine inside a live/work unit is allowed to be of combustible construction even in a noncombustible-construction building, provided it's no more than 25% of the unit's floor area (or 20 m², whichever is smaller) and has no obstructions higher than 1,070 mm above the floor.
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.