The Ontario Building Code | Heat Transfer
5.10.2.4. Heat Transfer
(1) windows, doors and skylights shall meet the heat transfer performance requirements in Section 5.3.
(2) Except as provided in Sentence (3), all metal-framed glazed assemblies separating interior conditioned space from interior unconditioned space or exterior space shall incorporate a thermal break to minimize condensation.
(3) Metal-framed glazed assemblies need not comply with Sentence (2) where these assemblies are,
(a) storm windows or doors, or
(b) windows or doors that are required to have a fire-protection rating.
5.10.3. exterior Insulation Finish Systems
In Plain Language
Windows, doors, and skylights must meet the heat transfer performance requirements set out in Section 5.3, and metal-framed glazed assemblies separating conditioned interior space face additional specific requirements.
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.