The Ontario Building Code | Installation of Closures
3.1.8.5. installation of Closures
(1) Except where fire dampers, window assemblies and glass block are used as closures, closures of the same fire-protection rating installed on opposite sides of the same opening are deemed to have a fire-protection rating equal to the sum of the fire-protection ratings of the closures.
(2) Except as otherwise specified in this Part, every door, window assembly or glass block used as a closure in a required fire separation,
(a) shall be installed in conformance with nfpa 80, "Fire doors and Other opening Protectives", and
(b) where required to have a fire-protection rating, shall have labels or classification marks to identify the testing laboratory.
(3) If a door is installed so that it could damage the integrity of a fire separation if its swing is unrestricted, door stops shall be installed to prevent the damage.
In Plain Language
Closures of matching rating on both sides of the same opening combine additively for rating purposes; doors, windows, and glass block used as closures generally must be installed per NFPA 80 and carry identifying labels or classification marks when a fire-protection rating is required.
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.