Canada Stair Code for Houses: NBC 2020 and Quebec
In Canada, the stairs in a house follow Section 9.8 of the National Building Code (NBC 2020): risers of 125 to 200 mm (4 15/16 to 7 7/8 in), runs of 255 to 355 mm (10 1/16 to 13 15/16 in), at least 860 mm (33 7/8 in) of width and 1950 mm (76 13/16 in) of headroom. Handrails sit 865 to 1070 mm (34 1/16 to 42 1/8 in) above the nosings and guards inside a house are at least 900 mm (35 7/16 in) high. Quebec's Construction Code has been based on the NBC 2020 since April 17, 2025 and keeps these numbers.
Summary table
Private stairs: those serving a single dwelling, a house with a secondary suite, or their garage (notes to Table 9.8.4.1).
| Rule | Imperial | Metric | NBC 2020 |
|---|---|---|---|
| Rise (riser height) | 4 15/16–7 7/8 in | 125–200 mm | 9.8.4.1, Table 9.8.4.1 |
| Run, rectangular treads | 10 1/16–13 15/16 in | 255–355 mm | 9.8.4.2, Table 9.8.4.2 |
| Nosing projection (tread depth minus run), maximum | 15/16 in | 25 mm | 9.8.4.2.(2) |
| Variation of risers or runs: adjacent / whole flight | 3/16 in / 3/8 in | 5 mm / 10 mm | 9.8.4.4 |
| Clear width, minimum | 33 7/8 in | 860 mm | 9.8.2.1.(4) |
| Headroom over stairs and landings, minimum | 76 13/16 in | 1950 mm | 9.8.2.2.(3), 9.8.6.4.(2) |
| Height of one flight, maximum | 12 ft 1 5/8 in | 3.7 m | 9.8.3.3 |
| Landing length, straight or turning less than 90° | 33 7/8 in | 860 mm | 9.8.6.3.(2) |
| Landing turning 90° or more (L or U stair), minimum length | width of the stair | width of the stair | 9.8.6.3.(1) |
| Handrail height | 34 1/16–42 1/8 in | 865–1070 mm | 9.8.7.4.(2) |
| Guard height inside a house, minimum | 35 7/16 in | 900 mm | 9.8.8.3.(2) |
| Guard required where the drop exceeds | 23 5/8 in within 47 1/4 in | 600 mm within 1.2 m | 9.8.8.1.(1) |
| Guard openings | 3 15/16 in sphere | 100 mm sphere | 9.8.8.5.(1) |
Which code applies to your stair
The NBC is a model code that provinces and territories adopt, often with changes; its Part 9 (Housing and Small Buildings) covers houses. The NBC 2025 is now published and keeps every value above, but each province adopts it on its own schedule.
In Quebec, Chapter I – Building of the Construction Code has been the NBC 2020 with Quebec amendments since April 17, 2025. Work started before October 17, 2027 may still follow the previous version, based on the NBC 2015. Houses are a special case: Chapter I exempts housing with no more than two storeys or eight dwellings (section 1.04), and the Régie du bâtiment du Québec explains that single-family houses, duplexes, triplexes and small residential buildings fall under municipal rules, each town choosing its edition. Ask your city which one applies.
Rise and run (9.8.4)
Rise and run are both measured from nosing to nosing, vertically and horizontally (Note A-9.8.4). Split the finished floor-to-floor height into equal risers: 2476.5 mm (97 1/2 in) in 13 risers gives 190.5 mm (7 1/2 in). See how to calculate stairs.
Adjacent risers may differ by 5 mm (3/16 in) and the tallest and shortest in a flight by 10 mm (3/8 in); runs follow the same tolerances (9.8.4.4). A tread may be at most 25 mm deeper than its run, which caps the nosing projection (9.8.4.2.(2)), and the top of the nosing needs a rounded or bevelled edge of 6 to 14 mm (9.8.4.8).
Width and headroom (9.8.2)
At least one stair between each floor level of a house, and any exterior stair serving one dwelling, needs 860 mm (33 7/8 in) of width (9.8.2.1.(4)). Handrails and the construction below them, stringers included, may project up to 100 mm (3 15/16 in) into it (9.8.7.6).
Headroom is measured vertically over the clear width, from a line tangent to the tread and landing nosings (9.8.2.2.(1)). It is 1950 mm (76 13/16 in) for a single dwelling, or 1850 mm (72 7/8 in) under beams and ducts in a secondary suite. The low point is usually the header of the stairwell opening above the lower steps.
Landings (9.8.6)
A landing is required at the top and bottom of every flight, and a finished floor counts as one (9.8.6.1.(3), 9.8.6.2.(1)). Inside a house, a door at the top that swings away from the stair needs no landing (9.8.6.2.(2)). One flight may rise at most 3.7 m (9.8.3.3).
The size rule catches many builders. A landing must be at least as wide and as long as the width of the stair (9.8.6.3.(1)). Only a landing that does not turn, or turns less than 90°, may stop at the required width: 860 mm (33 7/8 in) in a house (9.8.6.3.(2)). An L landing turns 90° and a U landing 180°, so a stair 1000 mm (39 3/8 in) wide needs a landing 1000 mm long, measured perpendicular to the nosings (9.8.6.3.(3)). The NRC's Illustrated User's Guide states the same general rule. The half-turn case is detailed in U-shaped stairs with a landing.
Handrails (9.8.7)
In a house, one handrail is required as soon as an interior stair has more than two risers (Table 9.8.7.1, 9.8.7.1.(3)). Its top sits 865 to 1070 mm (34 1/16 to 42 1/8 in) above the nosing line (9.8.7.4). It must be graspable from the bottom riser to the top riser, may start from a newel post or volute on the bottom tread (9.8.7.2), and needs 50 mm (2 in) of clearance from the wall (9.8.7.5). On tapered treads other than winders, it goes on the narrow side (9.8.7.1.(5)).
Older editions differ: the NBC 2010 capped handrails at 965 mm (37 15/16 in). A handrail between 865 and 965 mm satisfies both.
Guards (9.8.8)
A guard is required on each open side where the drop to a surface within 1.2 m (47 1/4 in) exceeds 600 mm (23 5/8 in) (9.8.8.1.(1)). Inside a house it is at least 900 mm (35 7/16 in) high, measured on a flight from the line through the nosings (9.8.8.3.(2) and (4)). Outside, 900 mm is enough up to 1800 mm (70 7/8 in) above the ground, and 1070 mm (42 1/8 in) above that. A 100 mm sphere must not pass through, and the triangle formed by riser, tread and bottom rail must stop a 150 mm (5 7/8 in) sphere (9.8.8.5).
Open risers are allowed in stairs serving a single dwelling (9.8.4.9), and Section 9.8 sets no maximum gap for them, unlike the US code's 4 in sphere. With young children, keeping the gaps under 100 mm is wise.
Winders (9.8.4.6)
Winders are allowed only in dwellings, with one set between floor levels (9.8.3.1). Each winder turns exactly 30° or 45° and a set turns at most 90° (9.8.4.6): a quarter turn takes three 30° winders or two 45° winders. Other tapered treads need at least 150 mm (5 15/16 in) at the narrow end (9.8.4.3).
Quebec additions
The Quebec text keeps these values and adds a few rules. No guard is required on an interior stair serving a basement used only for mechanical or maintenance equipment, if each open side has a handrail (9.8.8.1.(2)(d)). A spiral stair may be the only means of egress for up to six people, against three in the NBC (9.8.4.7.(2)).
Common mistakes
- Building an L or U landing 860 mm long while the flights are wider.
- Dividing the framing height instead of the finished floor-to-floor height, so the first or last riser misses the 5 mm tolerance.
- Leaving the floor structure out of the stairwell opening: the header then cuts into the 1950 mm headroom.
- Measuring a stair guard from the tread surface instead of the line through the nosings: it ends up too low.
FAQ
What is the maximum stair rise in Canada?
200 mm (7 7/8 in) for stairs serving a house, with a minimum of 125 mm (4 15/16 in) (Table 9.8.4.1). Public stairs are limited to 180 mm.
What is the minimum stair width for a house in Canada?
860 mm (33 7/8 in) (9.8.2.1.(4)). Handrails and stringers may project up to 100 mm into it (9.8.7.6).
How deep must a stair landing be in Canada?
On a straight run, 860 mm (33 7/8 in) is enough in a house. A landing that turns 90° or more, as on an L or U stair, must be at least as long as the stair is wide (9.8.6.3).
How high must a handrail be in Canada?
865 to 1070 mm (34 1/16 to 42 1/8 in) above the nosing line (9.8.7.4). Guards inside a house must be at least 900 mm (35 7/16 in) high (9.8.8.3).
Does Quebec use the 2020 National Building Code?
Yes, since April 17, 2025, with the previous version allowed for work started before October 17, 2027. For a house, your municipality picks the edition.
Are open risers allowed in Canada?
Yes, in stairs serving a single dwelling or a house with a secondary suite (9.8.4.9). Most other stairs need closed risers.
Stair3D gives you a design and a code check to guide your work. Check the measurements on site and with your local building authority before cutting.