Hardwood stair nosings and floor transitions

The detail that fails inspection

A carpeted flight converted to hardwood is mostly a nosing problem. Carpet hid the geometry; hardwood shows it, and the inspector measures it.

Ontario limits nosing projection to 25 mm. It is the single most common reason a retread flight is failed, because a retread cap sits on top of the existing tread and the easy way to make the cap look right is to let it hang further than it should.

Rise, run and tread depth are one calculation

Rise must not exceed 200 mm on a stair serving a dwelling unit. Run must be at least 210 mm. Tread depth — which is run plus the nosing projection, not run alone — must be at least 235 mm.

Those three interact, and a retread changes all of them at once. Adding a 20 mm cap to every tread does not change the rise between treads in the middle of the flight — but it does change the first rise from the floor below and the last rise to the floor above, and those two are where a flight most often goes out of tolerance.

The flooring going in at the top and bottom changes them again. A 3/4-inch solid floor at the top landing and a tile floor at the bottom are two different first and last risers.

Consistency matters as much as the limits

A code-compliant flight where one riser is 12 mm taller than its neighbours is still a flight people trip on. The variation between the tallest and shortest riser in a run is a real limit, not a nicety, and it is the thing a retread most easily gets wrong when the original stringers were cut by eye in 1954.

Measuring every riser before quoting is not thoroughness for its own sake. It is how you find out whether this flight can be retreaded at all or whether it needs new stringers.

Transitions at the top and bottom

Where the stair meets the floor is a joint between two assemblies that move differently. A landing tread with a returned end reads as millwork; a butt joint and a strip of quarter round reads as a repair.

The nosing profile should match down the whole flight and continue onto the landing, so the eye follows one line. Mixing a bullnose on the treads with a square edge on the landing is the detail that makes a good stair look subcontracted — which, on most flooring jobs, it was.

Before you sign

Ask whether the quote includes new stringers or assumes the existing ones are square, what the first and last riser will measure once the new floors are in, and who is responsible if the flight does not pass. Those three questions separate a stair builder from a flooring company that also does stairs.

Use the stair studio on this site to check a flight against the Ontario limits before anyone quotes it — it will not certify your stair, but it will tell you which dimension is the problem.