The Ontario Building Code | Climatic and Seismic Design Values
1.1.2.1. Climatic and Seismic design Values
(1) The climatic and seismic values required for the design of buildings under this Code shall be in conformance with the climatic and seismic values provided in MMAH Supplementary Standard SB-1, "Climatic and Seismic Data".
(2) The outside winter design temperatures determined from MMAH Supplementary Standard SB-1, "Climatic and Seismic Data", shall be those listed for the January 2.5% values.
In Plain Language
Rather than listing wind, snow, frost, and seismic design values directly in the Code, this clause points designers to a separate reference table, MMAH Supplementary Standard SB-1, for the actual climatic and seismic numbers used in structural design. Winter design temperatures specifically use the "January 2.5%" statistical value from that table, meaning the temperature that's colder than the outdoor temperature about 97.5% of the time in January.
Common Questions
Q: Where do I find the actual design values for my location?
They're in MMAH Supplementary Standard SB-1, "Climatic and Seismic Data," not in this article itself. Values vary by municipality.
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.