Stairs, handrails and guards in the National Building Code (Part 9)

What this page covers

This page summarizes the numbers in the National Building Code of Canada 2020 (NBC), Division B, Section 9.8 Stairs, Ramps, Handrails and Guards (Part 9), and its explanatory Notes. A cabinetmaker who builds stairs and railings needs them. The Code is paraphrased and cited by Article and printed page. This page covers only the NBC 2020 text; confirm which code applies to the project.

Private stairs and public stairs

Most limits depend on the type of stair:

• Private stairs are exterior and interior stairs that serve a single dwelling unit, a house with a secondary suite (including their common spaces), or a garage that serves either of these (Notes to Tables 9.8.4.1. and 9.8.4.2., pp. 9-22 to 9-23).
• Public stairs are all stairs that are not service stairs or private stairs.
• A dwelling unit is a suite used as a housekeeping unit, usually with cooking, eating, living, sleeping and sanitary facilities (Div. A, p. 1-6).
• A garage serving a single dwelling unit or a house with a secondary suite counts as part of the dwelling unit for these rules (Article 9.8.1.2., p. 9-21).

Step dimensions

Item	Private stair	Public stair	Where
Rise, maximum	200 mm	180 mm	Table 9.8.4.1., pp. 9-22 to 9-23
Rise, minimum	125 mm	125 mm	Table 9.8.4.1.
Run (rectangular treads), maximum	355 mm	no limit	Table 9.8.4.2., p. 9-23
Run (rectangular treads), minimum	255 mm	280 mm	Table 9.8.4.2.
Tread depth	at least the run, and not more than the run + 25 mm	same	Sentence 9.8.4.2.(2), p. 9-23

The rise and run limits do not apply to stairs serving only service rooms or service spaces, and spiral stairs follow their own rules (Article 9.8.4.7., below).

How to measure (Figure A-9.8.4.-B, p. 9-524):

• Rise: vertically, from nosing to nosing.
• Run: horizontally, from nosing to nosing. The Code defines run as "the horizontal distance between two adjacent tread nosings" (Div. A, p. 1-12).
• Tread depth: from the nosing to the riser.

Uniformity (Article 9.8.4.4., p. 9-24):

Tolerance	Risers	Rectangular treads (run)
Between adjacent steps	5 mm	5 mm
Largest vs smallest in a flight	10 mm	10 mm

• Treads may not slope more than 1 in 50.
• Where the top or bottom riser meets a sloping surface such as a driveway, the riser height across the stair may vary by up to 1 in 12. This does not apply to required exit stairs.

Nosings (Article 9.8.4.8., p. 9-25):

• The top of the nosing needs a rounded or bevelled edge that extends 6 mm to 14 mm, measured horizontally from the front of the nosing.
• If resilient material covers the nosing, the minimum may be reduced to 3 mm.
• Note A-9.8.4.8. (p. 9-526) explains the reason: the edge makes the tread easier to see, but a sloped portion that is too wide makes the foot more likely to slip.

Open risers (Article 9.8.4.9., p. 9-25) are not allowed, except in these stairs:

• stairs serving a single dwelling unit or a house with a secondary suite
• fire escape stairs
• stairs used mainly for maintenance
• stairs serving service rooms
• stairs in industrial occupancies other than storage garages

Stair configurations

Permitted configurations (Table A-9.8.3.1., p. 9-523):

Configuration	Within dwelling units	Public stairs	Exit stairs
Straight flight, rectangular treads	permitted	permitted	permitted
Curved flight, tapered treads	permitted	permitted	permitted (see Article 3.4.6.9.)
Winders	permitted	not permitted	not permitted
Mix of rectangular and tapered treads	permitted	not permitted	not permitted
Spiral stairs	permitted	permitted	not permitted

• Tapered treads have non-parallel edges, and their run increases or decreases uniformly over the width (Div. A, p. 1-13).
  • Except in winders, spiral stairs and required exit stairs, the run must be at least 150 mm at the narrow end, and must meet Table 9.8.4.2. when measured 300 mm from the centre line of the handrail at the narrow end (Article 9.8.4.3., p. 9-23).
  • The depth rule is the same as for rectangular treads: at least the run, and not more than the run + 25 mm.
  • All tapered treads in a flight must turn the same way (Sentence 9.8.3.1.(5), p. 9-22).
• Mixed flights within dwelling units: all treads must have a uniform run measured 300 mm from the centre line of the inside handrail. Tapered treads at the bottom of the flight may have a longer run (Article 9.8.4.5., p. 9-24).
• Winders (Article 9.8.4.6., p. 9-24):
  • Each tread turns through exactly 30° or exactly 45°.
  • One set may turn through no more than 90°.
  • Only one set of winders is allowed between floor levels (Sentence 9.8.3.1.(3)).
  • The possible turns are 30° or 45° (1 winder), 60° (2 winders) or 90° (2 or 3 winders) (Note A-9.8.4.6., p. 9-525).
  • The Note also says a landing is the safest way to turn a stair. Winders are accepted in dwelling units because occupants know their surroundings.

Spiral stairs (Article 9.8.4.7., p. 9-24; Figure A-9.8.4.7., p. 9-525):

Item	Requirement
Handrails	on both sides; outer handrail at least 1 070 mm high
Clear width between handrails	at least 660 mm
Riser height	not more than 240 mm
Tread depth	at least 190 mm, measured 300 mm from the handrail centre line at the narrower edge; consistent angle, uniform size, all turning the same way
Clear height	at least 1 980 mm
Use	may be the only means of egress for not more than 3 persons; may not serve as an exit

Widths, headroom, risers and flight height

Item	Value	Where
Required exit stairs and public stairs, residential buildings	at least 900 mm wide	Sentence 9.8.2.1.(1), p. 9-21
Exit stairs serving a single dwelling unit or a house with a secondary suite	at least 860 mm wide	Sentence 9.8.2.1.(2)
At least one stair between floor levels within a dwelling unit; exterior stairs serving a single dwelling unit (other than required exit stairs)	at least 860 mm wide	Sentence 9.8.2.1.(4)
Clear height over stairs, general	at least 2 050 mm	Sentence 9.8.2.2.(2), p. 9-22
Clear height, stairs serving a single dwelling unit or a house with a secondary suite	at least 1 950 mm	Sentence 9.8.2.2.(3)
Clear height under beams and ducting in secondary suites	at least 1 850 mm	Sentence 9.8.2.2.(4)
Minimum risers in an interior flight (not within a dwelling unit)	3	Article 9.8.3.2., p. 9-22
Maximum vertical height of one flight	3.7 m	Article 9.8.3.3., p. 9-22

Spiral stairs are excepted from most of the width and headroom values above; they need 660 mm between handrails and 1 980 mm clear height (Article 9.8.4.7.).

Clear height (headroom) is measured vertically, over the clear width of the stair, from a straight line tangent to the tread and landing nosings up to the lowest point above.

Landings

These rules are in Articles 9.8.6.2. and 9.8.6.3., pp. 9-26 to 9-27.

• Where landings are required:
  • at the top and bottom of each flight (including stairs in garages), subject to the exceptions in Sentences 9.8.6.2.(2) to (4)
  • where a doorway opens onto a stair or ramp
  • where a stair and a ramp meet
• Door at the top of a stair within a dwelling unit: if the door swings away from the stair, no landing is needed between the door and the stair.
• Door swinging toward a stair (any stair): the whole arc of the swing must be over the landing.
• Size: a landing must be at least as wide and as long as the stair width. If the landing does not turn, or turns less than 90°, its length need not be more than the lesser of the required stair width or 1 100 mm.
• Slope: not more than 1 in 50.
• Clear height over landings: 2 050 mm in general, or 1 950 mm for a single dwelling unit or a house with a secondary suite (Article 9.8.6.4., p. 9-27).

Handrails

Number of sides that need a handrail (Table 9.8.7.1., p. 9-27):

Location	Stairs < 1 100 mm wide, straight	Stairs < 1 100 mm wide, curved	Stairs ≥ 1 100 mm wide	Ramps < 1 100 mm	Ramps ≥ 1 100 mm
Within a dwelling unit or a house with a secondary suite	1	1	1	1	2
All other locations	1	2	2	2	2

• No handrail needed (single dwelling unit):
  • interior stairs with not more than 2 risers
  • exterior stairs with not more than 3 risers
  • ramps that rise not more than 400 mm
• Exterior stairs with more than 3 risers serving not more than one dwelling unit or a house with a secondary suite need only one handrail.
• Natural path of travel: except where a stair or ramp serves not more than two dwelling units, at least one handrail must be within 750 mm of the natural path of travel.
• Tapered treads within a dwelling unit (except stairs with winders): one handrail goes along the narrow end of the treads (Article 9.8.7.1., p. 9-27).

Handrail rule	Private (single dwelling unit / house with secondary suite)	Other stairs	Where
Height (required handrails)	865 mm to 1 070 mm	865 mm to 1 070 mm	Article 9.8.7.4., p. 9-28
Continuity	continuously graspable from the bottom riser to the top riser; may start from a newel post or volute on the bottom tread; may stop at landings	at least one required handrail continuous for the whole stair, including landings (except at doorways)	Article 9.8.7.2., pp. 9-27 to 9-28; Note A-9.8.7.2., p. 9-527
Extension past top and bottom of flight	not required	at least one handrail extends horizontally at least 300 mm	Article 9.8.7.3., p. 9-28
Clearance to the wall	at least 50 mm (60 mm if the wall is rough or abrasive)	same	Article 9.8.7.5., p. 9-28
Projection into required stair width (handrail, supports, stringers)	at most 100 mm	same	Article 9.8.7.6., p. 9-28
Concentrated load, any point and direction	0.9 kN	0.9 kN	Article 9.8.7.7., p. 9-28
Uniform load	not required for handrails serving a single dwelling unit	0.7 kN/m (all handrails other than those serving a single dwelling unit)	Article 9.8.7.7.

• Measuring height: handrail height is measured vertically from the top of the rail to a straight line tangent to the tread nosings (Figure A-9.8.7.4., p. 9-528). Extra handrails installed beyond the required ones do not have to meet the height range.
• Graspability: handrails must be graspable along their whole length, with nothing on or above them that breaks the handhold.
  • Fingers and thumb should be able to curl under part or all of the rail.
  • If they cannot reach the bottom, the rail needs finger recesses on both sides at the bottom of the graspable part. The recesses must be wide and deep enough and have no sharp edges (Note A-9.8.7.5.(2), pp. 9-528 to 9-529).
• Ends: end the rail so it does not block travel or create a hazard, for example by returning it to a wall, floor or post (Note A-9.8.7.3.(1), p. 9-528).
• Attachment (single dwelling unit, wood studs or blocking): the attachment is deemed to meet the load requirement if:
  • attachment points are no more than 1.2 m apart horizontally
  • the first point at each end is within 300 mm of the end of the rail
  • each point has at least 2 No. 8 wood screws penetrating at least 32 mm into solid wood (Sentence 9.8.7.7.(2), p. 9-28)

Guards

When a guard is required (Article 9.8.8.1., p. 9-29; Note A-9.8.8.1., p. 9-529): a guard is needed on each side not protected by a wall where the walking surface is more than 600 mm above the adjacent surface within 1.2 m. This applies to stairs, ramps, landings, porches, balconies and similar surfaces.

• Guards are not required:
  • at the leading edge at the top of a flight
  • at loading docks
  • at floor pits in repair garages
  • where access is for maintenance only
• The 1.2 m distance stops a guard being avoided by raising the grade right next to a deck or stair.

Guard rule	Within dwelling units / private	Other guards	Where
Minimum height	900 mm within dwelling units; 900 mm for exterior guards serving one dwelling unit where the walking surface is not more than 1 800 mm above finished ground (otherwise 1 070 mm)	1 070 mm	Article 9.8.8.3., p. 9-30
Openings (required guards)	must stop a 100 mm sphere	same (industrial guards may instead use rails with openings that stop a 535 mm sphere, Sentence 9.8.8.5.(3))	Sentence 9.8.8.5.(1), p. 9-31
Triangle formed by riser, tread and bottom rail	must stop a 150 mm sphere	same (except industrial)	Sentence 9.8.8.5.(2)
Guard that is not required (non-industrial)	openings must stop a 100 mm sphere or let a 200 mm sphere pass	same	Sentence 9.8.8.5.(4)
Non-climbable zone (required guard, level more than 4.2 m above the next level, non-industrial)	no member, attachment or opening that helps climbing between 140 mm and 900 mm above the protected level	same	Article 9.8.8.6., p. 9-31

• Measuring height: on stairs, guard height is measured vertically from the top of the guard to a line through the tread nosings (Sentence 9.8.8.3.(4)).
• Why lower guards are allowed in dwellings: occupants know the hazards, and crowding is less likely (Note A-9.8.8.3., p. 9-530).
• Openings of 100 mm to 200 mm: these can trap a child's head, which is why the 200 mm option exists for guards that are not required (Note A-9.8.8.5.(4), p. 9-530).
• Climbing examples (Note A-9.8.8.6.(1), pp. 9-530 to 9-531). Designs considered not to help climbing include:
  • protrusions more than 450 mm apart horizontally and vertically
  • protrusions with a horizontal offset of 15 mm or less
  • spaces no larger than 45 mm wide by 20 mm high

Loads on guards (Table 9.8.8.2., p. 9-30; the loads need not act together):

Guard location	Horizontal load at top (minimum required height)	Load on infill (balusters, panels)	Vertical load on top
Within dwelling units; exterior guards serving not more than two dwelling units	0.5 kN/m or 1.0 kN concentrated	0.5 kN over up to 300 mm × 300 mm	1.5 kN/m
Access ways to equipment platforms and similar	1.0 kN concentrated	0.5 kN over 100 mm × 100 mm	1.5 kN/m
All other guards	0.75 kN/m or 1.0 kN concentrated	0.5 kN over 100 mm × 100 mm	1.5 kN/m

• Checking baluster openings: with 0.1 kN applied to two adjacent balusters in opposite directions, in the plane of the guard, the opening must still meet the 100 mm rule (Sentence 9.8.8.2.(2), pp. 9-29 to 9-30).
• Guards in dwellings: where balusters are narrow and close enough, the infill load is placed so that it engages three balusters (Sentence 9.8.8.2.(3); Note A-9.8.8.2., p. 9-530).
• Glass in guards: must be laminated or tempered safety glazing conforming to CAN/CGSB-12.1, or wired glass conforming to CAN/CGSB-12.11-M (Article 9.8.8.7., p. 9-31).
• Glazing over stairs, ramps and landings: glazing that comes lower than 1 070 mm (900 mm in dwelling units) above the treads or landing must be protected by a guard or be non-openable and designed for balcony-guard loads (Sentences 9.8.8.1.(6) and (7), p. 9-29).

Construction of wood stairs

Item	Stairs serving one dwelling unit / house with secondary suite	Other stairs	Where
Specified load on stair	1.9 kPa	4.8 kPa	Article 9.8.9.1., p. 9-31
Stringer effective depth / overall depth	at least 90 mm / at least 235 mm	same	Article 9.8.9.4., p. 9-32
Stringer actual thickness	25 mm if supported along its length, 38 mm if unsupported	same	Article 9.8.9.4.
Stringer spacing	not more than 900 mm o.c. (up to 1 200 mm where risers support the front of the tread)	not more than 600 mm o.c.	Article 9.8.9.4.

• Treads within dwelling units: treads of lumber, plywood or OSB must be at least 25 mm actual thickness. Use at least 38 mm where open risers are permitted and the stringers are more than 750 mm apart (Article 9.8.9.5., p. 9-32).
• Grain direction: for plywood or OSB treads not continuously supported by the riser, the face grain runs at right angles to the stringers.
• Tread finish in dwelling units: treads and landings of interior stairs in dwelling units (other than stairs to unfinished basements) are finished with hardwood, vertical grain softwood, resilient flooring or an equivalent material.
• Slip resistance outside dwelling units and houses with a secondary suite: treads and landings of stairs, and ramps, there need a slip-resistant finish or slip-resistant strips that stand no more than 1 mm proud (Article 9.8.9.6., p. 9-32).
• Exterior wood steps: they must not touch the ground unless treated with a wood preservative (Article 9.8.9.3., p. 9-32).

Ramps (brief)

A ramp is a path of travel steeper than 1 in 20 (Div. A, p. 1-11).

• Width: at least 1 100 mm, or 860 mm when serving a single dwelling unit or a house with a secondary suite (Article 9.8.5.2., p. 9-25).
• Maximum slope: 1 in 10 for exterior ramps and for interior ramps in residential occupancies, 1 in 6 for industrial occupancies and 1 in 8 for all other occupancies (Article 9.8.5.4., p. 9-25).

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Source: National Building Code of Canada 2020, Division A, Article 1.4.1.2. (definitions), and Division B, Section 9.8 (pp. 9-21 to 9-32) with Notes A-9.8.3.1. to A-9.8.8.6.(1) (pp. 9-523 to 9-531). Paraphrased; check the code adopted in your province or territory.