Closing in an open stairwell in my Ottawa house, permit needed?

Closing in an open stairwell touches both the stair structure and the framing around it, and the permit question depends on what work is actually involved.

The City of Ottawa's permit list includes "interior and exterior structural alterations, such as adding or removing walls" and "structural repairs or alterations." If closing the stairwell means framing new walls, adding a header or altering the floor opening, that falls within what ottawa.ca describes as permit work. Confirm with the City before any framing begins. If the work is limited to adding a door in an existing opening of the same size, the City's exempt list covers same-size door replacements, though the work still has to meet the Ontario Building Code.

The 2024 Ontario Building Code sets minimum doorway sizes for a dwelling unit. A door leading to a stair that serves a floor with finished space requires an opening at least 810 mm wide by 1 980 mm high. A door to a room not otherwise listed is at least 760 mm by 1 980 mm. If the new door is smaller than those minimums, ask the carpenter and the City how that is handled before the frame is built.

If the stairwell opening in the floor is being reduced or the framing around it is changed, the carpenter and a qualified designer should look at how the floor framing is affected. Holes in floor framing are limited by the 2024 Code to not more than one quarter of the joist depth, at least 50 mm from the edges. Any change to the opening that affects the framing around it is worth having a designer review.

For the stair itself, the 2024 Code requires a guard where the drop beside a stair is more than 600 mm. Guards within a dwelling unit are at least 900 mm (about 35 1/2 in.) high. Openings in a guard must stop a 100 mm (about 4 in.) sphere. If closing the stairwell changes the guard or removes part of it, those numbers apply to whatever replaces it.