My kids climb the stair guard, what does Ontario code say?

There is a direct rule for this in the 2024 Ontario Building Code (O. Reg. 163/24). Nothing between 140 mm and 900 mm above the floor may make a guard climbable, unless it is shown not to be a hazard (9.8.8.6.). That is the zone children use as a ladder.

The Code also sets out what the openings in a guard must stop. Within a dwelling unit, openings must stop a 100 mm (about 4 in.) sphere (9.8.8.5.). The triangle formed under a stair guard has a slightly more generous limit: it must stop a 150 mm sphere. A guard inside a house must be at least 900 mm (about 35 1/2 in.) high (9.8.8.3.(2)), and it is required wherever the drop exceeds 600 mm (9.8.8.1.).

The climbability rule at 9.8.8.6. does not list specific balusters, rails or panel types that automatically pass or fail. It says the guard must not be climbable, or must be shown not to be a hazard. Guards built to MMAH Supplementary Standard SB-7 are deemed to comply with the Code's guard loading requirements (9.8.8.2.(6)). A carpenter or designer can look at what you have, compare it against SB-7 and the climbability clause, and tell you what a replacement or modification would need to look like.

A few things worth asking when you talk to a carpenter: whether the guard height meets the 900 mm minimum, whether the opening size stops a 100 mm sphere, and specifically how any proposed design addresses the climbability clause. Get the scope of work and any warranty in writing. The Consumer Protection Act, 2002 requires a direct agreement over $50 to be in writing and signed, and gives you 10 days to cancel after you receive your copy.

On the permit side, a guard replacement is not on either of the City of Ottawa's published lists, so ask the City whether your specific job needs a permit before work starts.

Before you commit, it is worth asking the carpenter directly whether they hold a Certificate of Qualification in carpentry, keeping in mind that the trade is non-compulsory in Ontario, so holding one is a choice, not a legal requirement.