Is horizontal cable railing allowed on an Ontario deck?

Horizontal cable infill on a required guard can facilitate climbing, which is what Ontario's no-climb rule targets. The 2024 Ontario Building Code, section 9.8.8.6(1) as replaced for Ontario, states that every required guard must be designed so that no member, attachment or opening located between 140 mm and 900 mm above the walking surface will facilitate climbing. Horizontal cables running between those heights are what that rule targets.

This is an Ontario-specific rule. The national version of the Code limits the no-climb requirement to guards more than 4.2 m above the level below. Ontario replaced that provision so the no-climb rule applies to every required guard, regardless of height above grade. A guard is required wherever the walking surface is more than 600 mm above the adjacent surface within 1.2 m of the edge, per section 9.8.8.1(1).

What this means for your deck

If a guard is required at that location, check any infill between 140 mm and 900 mm against that wording and confirm the design with the City. Any manufactured or pre-engineered guard system that falls outside the Code's prescriptive rules requires the manufacturer's information and attachment details to be submitted with the building permit application, as the City of Ottawa's permit requirements set out.

Guard height also matters here. For an exterior guard serving not more than one dwelling unit, the minimum is 900 mm where the walking surface is not more than 1 800 mm above finished ground level, and 1 070 mm in all other cases, per section 9.8.8.3. Openings through the guard must prevent the passage of a 100 mm sphere, and the triangle formed by the riser, tread and bottom rail on a stair guard must prevent the passage of a 150 mm sphere, per section 9.8.8.5.

If a builder or supplier says a horizontal cable guard meets the Ontario rule, ask them to point to the specific Code provision. The answer should reference section 9.8.8.6(1) as replaced for Ontario, not the national version of the rule.

Comparing guard quotes is easier on four points: what the footing or pile type is and how deep it goes, what board material and grade is specified, how the guards and stairs are detailed including infill style and height, and whether removal of an existing deck is included or priced separately.