The Ontario Building Code | Exception for Exterior Walls
220.127.116.11. Exception for exterior Walls
(1) The limit on the rise of temperature on the unexposed surface of an assembly as required by the tests referred to in Sentence 18.104.22.168.(1) shall not apply to an exterior wall that has a limiting distanceof 1.2 m or more, provided correction is made for radiation from the unexposed surface in accordance with Sentence 22.214.171.124.(9).