What is the 13 mm rule for thresholds in Ontario?

The 13 mm bevel rule comes from Section 3.8 of the Ontario Building Code, which governs barrier-free design in public buildings. It does not apply to detached houses, semi-detached houses, duplexes, triplexes, townhouses or row houses.

We found no Part 9 threshold height limit for a house like the one Section 3.8 sets for public buildings. If you are planning threshold work as part of a broader accessibility renovation, the relevant Code requirements for your house are the ones governing ramps, landings and floor finishes, not the public-building barrier-free rules.

What this means for a home renovation

If a contractor or a website tells you your house threshold "must" meet the 13 mm rule, that is a reference to the public-building standard, not the house standard. The Building Code does require that ramp and landing finishes be wear-resistant, slip-resistant, smooth, even and free from open defects (Article 9.8.9.6), which is relevant where a ramp meets a door.

Permits for threshold work alone are not on the City of Ottawa's permit list, and we found no specific permit requirement for replacing a threshold in place. If the work involves moving a door, enlarging a door opening, or altering the structure, those are on the City's permit list and a permit would be required. When in doubt, ask Building Code Services at the City of Ottawa before the work begins.

New flooring is on the City's list of projects that do not need a permit; for anything more, describe the work to Building Code Services.