Replacing the interior stairs in my Westboro house, permit needed?

Replacing an interior staircase in Westboro falls into a grey area on the City's permit lists. A new or rebuilt interior stair is not listed on either the City of Ottawa's permit-required list or its exempt list, so the right step is to ask Building Code Services at ottawa.ca before any work starts.

What the permit question depends on

If the replacement involves structural changes to the floor opening, the surrounding framing, or the bearing points of the stringers, that work touches "structural alterations," which the City does list as permit work. If the scope is limited to swapping out treads, risers and stringers within the same opening and footprint, the picture is less clear. Either way, confirm with the City before the carpenter starts.

When a permit does apply, the City's fee for alterations is $12.75 per $1,000 of construction value, with a minimum of $117. Construction value covers all materials, labour, overhead and professional fees. The City sets the valuation.

The 2024 Ontario Building Code (O. Reg. 163/24) sets the dimensions a replacement stair must meet. For private stairs within a dwelling unit, rise is between 125 mm and 200 mm, run between 255 mm (about 10 in.) and 355 mm, measured nosing to nosing. Width is at least 860 mm (about 34 in.) for at least one stair between each floor level. Headroom is at least 1 950 mm over the stair and landings. Wood stringers need an effective depth of at least 90 mm and an overall depth of at least 235 mm, spaced not more than 900 mm apart, with treads at least 25 mm thick. Risers and treads within a flight must be within 5 mm of each other and within 10 mm across the whole flight.

A fair quote for this job should itemise each of these separately:

• the building permit, if the City requires one
• materials (stringers, treads, risers, newel posts, handrail)
• labour for demolition and installation
• patching and finishing where the stair meets walls and floors
• disposal of the old stair

Ask the carpenter whether the existing floor opening stays the same size or changes, because that affects both the structural scope and the permit question. Get the answer in writing along with the full scope and price before anyone picks up a tool. If the house was built before 1960, ask about testing old paint or plaster before disturbing it.

Before the first nail goes in, make sure you have the written contract with the full scope and price, any permit the City requires, and any design drawings the permit application called for, all in hand.