What makes a deck guard climbable under Ontario rules?

Under Ontario's Building Code, a required guard is considered climbable if any member, attachment or opening located between 140 mm and 900 mm above the walking surface would facilitate climbing. That is the rule in section 9.8.8.6(1) of the 2024 Ontario Building Code, as replaced for Ontario, and it applies to every required guard on a residential deck.

The national version of that rule limits the no-climb requirement to guards more than 4.2 metres above the level below. Ontario removed that height threshold entirely. So on any required guard in Ontario, the same no-climb zone applies between 140 mm and 900 mm above the walking surface, whatever the deck's height.

What this means in practice

The rule is about members, attachments or openings in that zone that facilitate climbing. Two designs it speaks to directly:

• Horizontal rails running between posts within the 140 mm to 900 mm zone
• Cable infill installed horizontally within that zone

The 2024 Ontario Building Code wording is that no member, attachment or opening in that band will facilitate climbing, so check any design, including its attachment details, against it.

A few other numbers connect to this. Openings through a guard must prevent the passage of a 100 mm sphere, under section 9.8.8.5. On a stair guard, the triangle formed by the riser, tread and bottom rail must prevent the passage of a 150 mm sphere. Guard height is a separate question: exterior guards serving not more than one dwelling unit may be 900 mm high where the walking surface is not more than 1 800 mm above finished ground, and 1 070 mm in all other cases, under section 9.8.8.3.

For manufactured or glass guard systems that fall outside the Code's prescriptive rules, the City of Ottawa asks for the manufacturer's information and attachment details as part of the building permit application. The permit drawings must show the guard and handrail information on the elevations. Never assume a named product meets the no-climb requirement without checking the manufacturer's documentation against the 140 mm to 900 mm zone.

If you are unsure whether a guard design you have been quoted satisfies section 9.8.8.6(1), ask the City's Building Code Services or have the designer confirm it in writing before the permit is submitted. The City's framing inspection is at completion of structural framing and guards, and the final inspection at completion of the deck framing, stairs and guards.

The request form on this page sends your project details to Ottawa deck builders listed in the Ottawa Construction Network directory.