What does 'grade' mean in the Ontario Building Code?
Grade is the lowest of the average levels of finished ground adjoining each exterior wall of a building, ignoring localized depressions like window wells and vehicle or pedestrian entrances.
Paraphrased for clarity — open this provision in the BUILDAiD Library for the exact wording.
Grade is the datum for many Part 9 decisions: whether a level is a basement or a storey, building height, window well and egress details, and exit locations. On flat lots it is straightforward; on sloped sites you must average the finished ground along each exterior wall, then take the lowest of those averages. Because grade uses finished ground, landscaping and final grading plans can shift it. Document it clearly on drawings to avoid disputes with the building department at permit review.
Grade is basically the ground level around your building, averaged along each wall, using the lowest wall's average. Small dips like window wells and stairwells don't count. The code measures building height and basements from this line.
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This page is provided for general information. Building code requirements depend on your specific project, occupancy and municipality, and code editions change. Always verify requirements against the current Ontario Building Code and confirm with your local building department.