The Ontario Building Code | Guards
3.3.1.17. Guards
(1) Except as provided in Sentence (6) and Articles 3.3.2.8. and 3.3.4.7., a guard not less than 1 070 mm high shall be provided,
(a) around each roof to which access is provided for other than maintenance,
(b) at openings="http://thehandyforce.com/windows/" title ="Window installer in Toronto">openings into smoke shafts referred to in Subsection 3.2.6. that are less than 1 070 mm above the floor, and
(c) at each raised floor, mezzanine, balcony, gallery, interior or exterior vehicular ramp, and at other locations where the difference in level is more than 600 mm.
(2) Except as provided in Sentence (3) and Sentence 3.3.2.8.(4), openings="http://thehandyforce.com/windows/" title ="Window installer in Toronto">openings through any guard that is required by Sentence (1) shall be of a size that will prevent the passage of a sphere having a diameter more than 100 mm unless it can be shown that the location and size of openings="http://thehandyforce.com/windows/" title ="Window installer in Toronto">openings that exceed this limit do not represent a hazard.
(3) openings="http://thehandyforce.com/windows/" title ="Window installer in Toronto">openings through any guard that is required by Sentence (1) and that is installed in a buildingof industrial occupancy shall be of a size which will prevent the passage of a sphere having a diameter more than 200 mm unless it can be shown that the location and size of openings="http://thehandyforce.com/windows/" title ="Window installer in Toronto">openings that exceed this limit do not represent a hazard.
(4) openings="http://thehandyforce.com/windows/" title ="Window installer in Toronto">openings through any guard that is not required by Sentence (1) and that serves a buildingof other than industrial occupancy, shall be of a size that,
(a) will prevent the passage of a sphere having a diameter more than 100 mm, or
(b) will permit the passage of a sphere having a diameter more than 200 mm unless it can be shown that the location and size of openings that exceed these limits do not represent a hazard.
(5) Unless it can be shown that the location and size of openings do not present a hazard, a guard shall be designed so that no member, attachment or opening located between 140 mm and 900 mm above the level protected by the guard will facilitate climbing.
(6) Sentence (1) does not apply at the front edges of stages, floor pits in repair garagesand loading docks.
In Plain Language
This clause covers protective guards required around raised areas: roofs with access, balconies, mezzanines, ramps, and similar edges. As a general rule, if a walking surface is more than 600 mm (about 2 ft) above the adjacent level, a guard at least 1,070 mm (about 42 in) high is required, subject to specific exceptions listed in the article. Openings in the guard are also limited in size so small children can't slip through or get stuck.
Common Questions
Q: How high does a deck or balcony guard need to be?
Under this clause, guards are generally required to be at least 1,070 mm (about 42 in) high wherever the drop to the adjacent level exceeds 600 mm (about 24 in), subject to the exceptions noted in the article.
Q: How wide can the gaps in a guard or railing be?
Openings generally can't allow a 100 mm sphere (about 4 in) to pass through, so a small child can't slip through or become stuck, with a looser 200 mm limit for industrial occupancies.
This is a plain-language summary of the 2012/2017 Ontario Building Code text above, for general understanding only and not a substitute for the Code. Always confirm current requirements against the 2024 edition (O.Reg. 163/24) or a qualified professional before construction.