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When this shows up on the exam
Both the House and Small Buildings exams use Section 9.8 for short number problems. You are given a deck height, a riser count, grade elevations, a stair width or a guard length, and asked for a guard height, a handrail count, a baluster spacing or a load. The code values are simple. The marks are lost on how things are measured: from which surface, over what distance, and which row of a table applies.
The method
- Find the drop. Measure the difference in elevation from the walking surface to the lowest point of the adjacent surface within 1.2 m horizontally. Sloping ground counts. A guard is required where that difference is more than 600 mm, except at the leading edge at the top of a flight OBC Div. B 9.8.8.1.OBC Div. B 9.8.8.1. Required Guards(1) Except as provided in Sentence (2) and except at the leading edge at the top of a flight, every surface to which access is provided, including but not limited to flights of steps and ramps, exterior landings, porches, balconies, mezzanines, galleries and raised walkways, shall be protected by a guard on each side…. For a stair, the drop is the riser height times the number of risers.
- Pick the guard height OBC Div. B 9.8.8.3.OBC Div. B 9.8.8.3. Height of Guards(1) Except as provided in Sentences (2) to (3.1), all guards shall be not less than 1,070 mm high. (2) All guards within dwelling units or within houses with a secondary suite including their common spaces shall be not less than 900 mm high. (3) Exterior guards serving not more than one dwelling unit or a house with a…:
- 1,070 mm is the general minimum.
- 900 mm applies to guards inside a dwelling unit, or inside a house with a secondary suite.
- 900 mm also applies to exterior guards serving one dwelling unit where the walking surface is not more than 1,800 mm above finished ground.
- 1,500 mm applies to exterior stairs and landings more than 10 m above adjacent ground.
- On a flight, measure from the line through the tread nosings.
- Check the openings. A required guard must stop a 100 mm sphere. The triangle under a stair guard must stop a 150 mm sphere. A guard that is not required may either stop a 100 mm sphere or let a 200 mm sphere pass OBC Div. B 9.8.8.5.OBC Div. B 9.8.8.5. Openings in Guards(1) Except as permitted in Sentences (3) and (4), openings through guards shall be of a size that prevents the passage of a spherical object having a diameter of 100 mm. (See Note A-9.8.8.5.(1) and (3)) (2) Except for guards that serve industrial occupancies, the triangular openings formed by stair risers, stair…. Clear gap = centre-to-centre spacing minus baluster width.
- Check the climbing zone. Members between 140 mm and 900 mm above the protected walking surface must not make the guard easy to climb OBC Div. B 9.8.8.6.OBC Div. B 9.8.8.6. Guards Designed Not to Facilitate Climbing(1) Guards required by Article 9.8.8.1., except those in industrial occupancies and where it can be shown that the location and size of openings do not represent a hazard, shall be designed so that no member, attachment or opening located between 140 mm and 900 mm above the floor or walking surface protected by the…. Measure from the finished walking surface, not the structure.
- Count handrails. Use Table 9.8.7.1: row by location (in a dwelling unit or not), column by stair or ramp, width under or at least 1,100 mm, straight or curved. Then apply the exemptions for small stairs in a single dwelling unit (2 interior risers, 3 exterior risers, ramps rising 400 mm or less). For stairs required to be 2,200 mm or wider because of occupant load, no point may be more than 825 mm from a handrail OBC Div. B 9.8.7.1.OBC Div. B 9.8.7.1. Required Handrails(1) Except as provided in Sentences (2) to (4), handrails shall be installed on stairs and ramps in conformance with Table 9.8.7.1. (2) Where a stair or ramp is required to be at least 2,200 mm wide due to the occupant load, a handrail shall be installed such that no position on the stair or ramp is more than 825 mm….
- Check handrail height and clearances. Required handrails are 865 mm to 1,070 mm high, measured vertically to a line tangent to the nosings OBC Div. B 9.8.7.4.OBC Div. B 9.8.7.4. Height of Handrails(1) The height of handrails on stairs and ramps shall be measured vertically from the top of the handrail to (a) a straight line drawn tangent to the tread nosings of the stair served by the handrail, or (b) the surface of the ramp, floor or landing served by the handrail. (2) Except as provided in Sentence (3)…. Leave at least 50 mm behind the rail (60 mm if the wall is rough) OBC Div. B 9.8.7.5.OBC Div. B 9.8.7.5. Ergonomic Design(1) The clearance between a handrail and any surface behind it shall be not less than (a) 60 mm, if the surface behind the handrail is rough or abrasive, or (b) 50 mm, in all other cases. (2) All handrails shall be constructed so as to be continually graspable along their entire length with no obstruction on or above…. Outside single dwellings, one handrail extends at least 300 mm past the top and bottom of each flight OBC Div. B 9.8.7.3.OBC Div. B 9.8.7.3. Termination of Handrails(1) Handrails shall be terminated in a manner that will not obstruct pedestrian travel or create a hazard. (See Note A-9.8.7.3.(1)) (2) Except for stairs and ramps serving only one dwelling unit or a house with a secondary suite including their common spaces, at least one handrail at the sides of a stair or ramp shall….
- Loads. Table 9.8.8.2 is the guard load table, not a height table OBC Div. B Table 9.8.8.2.OBC Div. B Table 9.8.8.2. Minimum Specified LoadsTable 9.8.8.2. — Minimum Specified Loads Forming Part of Sentence 9.8.8.2.(1) Location of Guard | Horizontal Load Applied Inward or Outward at any Point at the Minimum Required Height of the Guard | Horizontal Load Applied Outward on Elements Within the Guard, Including Solid Panels and Balusters | Evenly Distributed…. Pick the row, then multiply the kN/m value by the guard length for a total. Part 4 gives the same idea in OBC Div. B 4.1.5.14.OBC Div. B 4.1.5.14. Loads on Guards and Handrails)(1) The minimum horizontal specified live load applied outward at the minimum required height of every required guard shall be (a) 3.0 kN/m for open viewing stands without fixed seats and for means of egress in grandstands, stadia, bleachers and arenas, (b) 1.0 kN applied at any point, so as to produce the most….
Worked example 1: sloping ground beside a deck
A deck serving one house is 520 mm above the ground at its edge. The ground falls away at 1 in 8.
| Step | Working | Result |
|---|---|---|
| Fall within 1.2 m | 1,200 / 8 | 150 mm |
| Drop to lowest point within 1.2 m | 520 + 150 | 670 mm |
| Compare with 600 mm | 670 is more than 600 | guard required |
| Height above ground | 670 mm, well under 1,800 mm | 900 mm guard |
Measured only at the edge (520 mm), you would wrongly skip the guard. The answer is a 900 mm guard, per 9.8.8.1.(1) and 9.8.8.3.(3).
Worked example 2: a wide stair in a Part 9 building
An exit stair in a building of other than residential occupancy serves 375 persons. At 8 mm per person it must be 375 x 8 = 3,000 mm wide OBC Div. B 9.8.2.1.OBC Div. B 9.8.2.1. Stair Width(1) Except as provided in Sentence (2) and Article 9.8.4.7., required exit stairs and public stairs serving buildings of residential occupancy shall have a width of not less than 900 mm. (2) Exit stairs serving a single dwelling unit or a house with a secondary suite including their common spaces shall have a width of…. How many handrails?
| Step | Working | Result |
|---|---|---|
| Sentence 9.8.7.1.(2) applies | width required is at least 2,200 mm | 825 mm rule |
| Two side rails cover | 2 x 825 | 1,650 mm |
| Uncovered middle strip | 3,000 - 1,650 | 1,350 mm |
| One middle rail covers | 2 x 825 = 1,650, which is at least 1,350 | enough |
| Check spacing | 3 rails at 1,500 mm, worst point 750 mm | complies |
Answer: 3 handrails. Table 9.8.7.1 alone gives only 2, which is the trap.
Worked example 3: checking handrail height on a stair
Rise 180 mm, run 280 mm. An inspector measures 960 mm from the tread surface to the top of the rail, at a point 140 mm back from the nosing.
| Step | Working | Result |
|---|---|---|
| Nosing line slope | 180 / 280 | 0.643 |
| Nosing line above tread at 140 mm back | 140 x 0.643 | 90 mm |
| Handrail height | 960 - 90 | 870 mm |
| Range check | 865 to 1,070 mm | complies |
The height is measured to the nosing line, not to the tread, under 9.8.7.4.(1).
Worked example 4: balusters and loads on a guard
A required guard outside any dwelling unit runs 3.0 m between posts (2,950 mm clear). Balusters are 38 mm wide.
| Step | Working | Result |
|---|---|---|
| Gaps for n balusters | (2,950 - 38n) / (n + 1) | must be under 100 mm |
| Solve | 2,950 - 38n < 100n + 100, so n > 20.65 | 21 balusters |
| Check | (2,950 - 798) / 22 | 97.8 mm |
| Horizontal load (Table 9.8.8.2, row "All other guards") | 0.75 kN/m x 3.0 m | 2.25 kN total |
| Vertical load at top | 1.5 kN/m x 3.0 m | 4.5 kN total |
With 20 balusters the gap is (2,950 - 760) / 21 = 104.3 mm, too wide.
Common mistakes
- Measuring the drop only at the edge and ignoring ground that slopes away within 1.2 m.
- Treating exactly 600 mm as needing a guard. The trigger is more than 600 mm.
- Using 900 mm for every house guard. For exterior guards, 900 mm only works up to 1,800 mm above finished ground.
- Counting treads instead of risers for the 2-riser and 3-riser handrail exemptions.
- Forgetting the floor-to-grade height when testing the 10 m rule for 1,500 mm guards.
- Measuring handrail or stair guard height from the tread surface instead of the nosing line.
- Using centre-to-centre baluster spacing as the opening. The opening is the clear gap.
- Rounding baluster counts down, or forgetting there is one more gap than balusters.
- Measuring the 140 mm to 900 mm climbing zone from the slab when pavers or decking raise the walking surface.
- Reading Table 9.8.8.2 as a height table, or using the dwelling-unit row (0.5 kN/m) for a public guard.
Find it fast in the code PDF
Bookmark Division B > Part 9 > Section 9.8, then Subsection 9.8.7 for handrails and 9.8.8 for guards. Ctrl+F phrases that work:
- "adjacent surface within 1.2 m" (guard trigger, 9.8.8.1)
- "not more than 1,800 mm above the finished ground level" (900 mm exterior guards, 9.8.8.3)
- "more than 825 mm from a handrail" (wide stairs, 9.8.7.1)
- "tangent to the tread nosings" (handrail height, 9.8.7.4)
- "spherical object having a diameter of 100 mm" (openings, 9.8.8.5)
- "between 140 mm and 900 mm" (climbing, 9.8.8.6)
- "Minimum Specified Loads" (Table 9.8.8.2)
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Code cited in this method
Based on the official 2024 Building Code Compendium on ontario.ca.
© King's Printer for Ontario, 2024. Reproduced with permission.
OBC Div. B 9.8.8.1. Required Guards
Open OBC Div. B 9.8.8.1. in the code viewer(1)Except as provided in Sentence (2) and except at the leading edge at the top of a flight, every surface to which access is provided, including but not limited to flights of steps and ramps, exterior landings, porches, balconies, mezzanines, galleries and raised walkways, shall be protected by a guard on each side that is not protected by a wall for the length where the difference in elevation is more than 600 mm between the walking surface and the adjacent surface within 1.2 m.
(2)Guards are not required
(a)at loading docks,
(b)at floor pits in repair garages, or
(c)where access is provided for maintenance purposes only.
(3)Doors in buildings of residential occupancy, where the finished floor on one side of the door is more than 600 mm above the floor or other constructed surface or ground level on the other side of the door, shall be protected by
(a)a guard, or
(b)a mechanism capable of controlling the free swinging or sliding of the door so as to limit any clear unobstructed opening to not more than 100 mm.
(4)Except as provided in Sentence (5), openable windows in buildings of residential occupancy shall be protected by
(a)a guard, or
(b)a mechanism that can only be released with the use of tools or special knowledge to control the free swinging or sliding operation of the openable part of the window so as to limit any clear unobstructed opening to not more than 100 mm measured either vertically or horizontally. (See Note A-9.8.8.1.(4))
(5)Windows need not be protected in accordance with Sentence (4), where the bottom edge of the openable portion of the window is located
(a)more than 900 mm above the finished floor, or
(b)less than 1,800 mm above the floor or ground on the other side of the window. (See Note A-9.8.8.1.(4))
(6)Except as provided in Sentence (7), glazing installed over stairs, ramps and landings that extends to less than 1,070 mm above the surface of the treads, ramp or landing shall be
(a)protected by guards in accordance with this Subsection, or
(b)non-openable and designed to withstand the specified lateral loads for guards as provided in Article 4.1.5.14.
(7)In dwelling units, glazing installed over stairs, ramps and landings that extends to less than 900 mm above the surface of the treads, ramp or landing shall be
(a)protected by guards in accordance with this Subsection, or
(b)non-openable and designed to withstand the specified lateral loads for guards as provided in Article 4.1.5.14.
(8)Glazing installed in public areas that extends to less than 1 m from the floor and is located above the second storey in buildings of residential occupancy shall be
(a)protected by guards in accordance with this Subsection, or
(b)non-openable and designed to withstand the specified lateral loads for guards as provided in Article 4.1.5.14.
OBC Div. B 9.8.8.3. Height of Guards
Open OBC Div. B 9.8.8.3. in the code viewer(1)Except as provided in Sentences (2) to (3.1), all guards shall be not less than 1,070 mm high.
(2)All guards within dwelling units or within houses with a secondary suite including their common spaces shall be not less than 900 mm high.
(3)Exterior guards serving not more than one dwelling unit or a house with a secondary suite including their common spaces shall be not less than 900 mm high where the walking surface served by the guard is not more than 1,800 mm above the finished ground level.
(3.1)The height of guards for exterior stairs and landings more than 10 m above adjacent ground level shall be not less than 1,500 mm.
(4)The height of guards for flights of steps shall be measured vertically from the top of the guard to a line drawn through the tread nosing served by the guard.
OBC Div. B 9.8.8.5. Openings in Guards
Open OBC Div. B 9.8.8.5. in the code viewer(1)Except as permitted in Sentences (3) and (4), openings through guards shall be of a size that prevents the passage of a spherical object having a diameter of 100 mm. (See Note A-9.8.8.5.(1) and (3))
(2)Except for guards that serve industrial occupancies, the triangular openings formed by stair risers, stair treads and the bottom element of a required guard shall be of a size that prevents the passage of a 150 mm diam sphere.
(3)Except where they serve storage garages, guards in industrial occupancies are permitted to consist of
(a)a top railing, and
(b)one or more horizontal intermediate rails spaced such that the size of the openings through the guard prevents the passage of a spherical object having a diameter of 535 mm. (See Note A-9.8.8.5.(1) and (3))
(4)Openings through any guard that is not required by Article 9.8.8.1. and that serves an occupancy other than industrial occupancy, shall be of a size that
(a)prevents the passage of a spherical object having a diameter of 100 mm, or
(b)permits the passage of a spherical object having a diameter of 200 mm. (See Note A-9.8.8.5.(4))
OBC Div. B 9.8.8.6. Guards Designed Not to Facilitate Climbing
Open OBC Div. B 9.8.8.6. in the code viewer(1)Guards required by Article 9.8.8.1., except those in industrial occupancies and where it can be shown that the location and size of openings do not represent a hazard, shall be designed so that no member, attachment or opening located between 140 mm and 900 mm above the floor or walking surface protected by the guard will facilitate climbing. (See Note A-9.8.8.6.(1))
OBC Div. B 9.8.7.1. Required Handrails
Open OBC Div. B 9.8.7.1. in the code viewer(1)Except as provided in Sentences (2) to (4), handrails shall be installed on stairs and ramps in conformance with Table 9.8.7.1.
(2)Where a stair or ramp is required to be at least 2,200 mm wide due to the occupant load, a handrail shall be installed such that no position on the stair or ramp is more than 825 mm from a handrail. (See Note A-9.8.7.1.(2))
(3)Handrails are not required for stairs and ramps serving a single dwelling unit, where
(a)interior stairs have not more than 2 risers,
(b)exterior stairs have not more than 3 risers, or
(c)ramps rise not more than 400 mm.
(4)Only one handrail is required on exterior stairs having more than 3 risers provided such stairs serve not more than one dwelling unit or a house with a secondary suite.
(5)Except for stairs with winders, where a flight of stairs within a dwelling unit consists of tapered treads, or a mix of tapered treads and rectangular treads, one handrail shall be installed along the narrow end of the treads.
OBC Div. B 9.8.7.4. Height of Handrails
Open OBC Div. B 9.8.7.4. in the code viewer(1)The height of handrails on stairs and ramps shall be measured vertically from the top of the handrail to
(a)a straight line drawn tangent to the tread nosings of the stair served by the handrail, or
(b)the surface of the ramp, floor or landing served by the handrail.
(2)Except as provided in Sentence (3), Clause 3.8.3.4.(1)(e) and Sentence 9.8.4.7.(1), required handrails shall be 865 mm to 1,070 mm high.
(3)Handrails installed in addition to required handrails need not comply with Sentence (2).
OBC Div. B 9.8.7.5. Ergonomic Design
Open OBC Div. B 9.8.7.5. in the code viewer(1)The clearance between a handrail and any surface behind it shall be not less than
(a)60 mm, if the surface behind the handrail is rough or abrasive, or
(b)50 mm, in all other cases.
(2)All handrails shall be constructed so as to be continually graspable along their entire length with no obstruction on or above them to break a handhold. (See Note A-9.8.7.5.(2))
OBC Div. B 9.8.7.3. Termination of Handrails
Open OBC Div. B 9.8.7.3. in the code viewer(1)Handrails shall be terminated in a manner that will not obstruct pedestrian travel or create a hazard. (See Note A-9.8.7.3.(1))
(2)Except for stairs and ramps serving only one dwelling unit or a house with a secondary suite including their common spaces, at least one handrail at the sides of a stair or ramp shall extend horizontally not less than 300 mm beyond the top and bottom of each flight or ramp. (See Note A-9.8.7.3.(2))
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OBC Div. B Table 9.8.8.2. Minimum Specified Loads
Open OBC Div. B Table 9.8.8.2. in the code viewerTable 9.8.8.2. — Minimum Specified Loads Forming Part of Sentence 9.8.8.2.(1) Location of Guard | Horizontal Load Applied Inward or Outward at any Point at the Minimum Required Height of the Guard | Horizontal Load Applied Outward on Elements Within the Guard, Including Solid Panels and Balusters | Evenly Distributed Vertical Load Applied at the Top of the Guard Guards within dwelling units and exterior guards serving not more than 2 dwelling units | 0.5 kN/m or concentrated load of 1.0 kN applied at any point[1] | 0.5 kN applied over a maximum width of 300 mm and a height of 300 mm[2] | 1.5 kN/m Guards serving access ways to equipment platforms and similar areas where the gathering of many people is improbable | Concentrated load of 1.0 kN applied at any point | Concentrated load of 0.5 kN applied over an area of 100 mm by 100 mm located at any point on the element or elements so as to produce the most critical effect | 1.5 kN/m All other guards | 0.75 kN/m or concentrated load of 1.0 kN applied at any point[1] | Concentrated load of 0.5 kN applied over an area of 100 mm by 100 mm located at any point on the element or elements so as to produce the most critical effect | 1.5 kN/m Notes to Table 9.8.8.2.: (1) The load that creates the most critical condition shall apply. (2) See Sentence (3).
OBC Div. B 4.1.5.14. Loads on Guards and Handrails)
Open OBC Div. B 4.1.5.14. in the code viewer(1)The minimum horizontal specified live load applied outward at the minimum required height of every required guard shall be
(a)3.0 kN/m for open viewing stands without fixed seats and for means of egress in grandstands, stadia, bleachers and arenas,
(b)1.0 kN applied at any point, so as to produce the most critical effect, for access ways to equipment platforms, contiguous stairs and similar areas where the gathering of many people is improbable, and
(c)0.75 kN/m or 1.0 kN applied at any point so as to produce the most critical effect, whichever governs for locations other than those described in Clauses (a) and (b).
(2)The minimum horizontal specified live load applied inward at the minimum required height of every required guard shall be half that specified in Sentence (1).
(3)Individual elements within the guard, including solid panels and pickets, shall be designed for a horizontal specified live load of 0.5 kN applied outward over an area of 100 mm by 100 mm located at any point on the element or elements so as to produce the most critical effect.
(4)The size of the opening between any two adjacent vertical elements within a guard shall not exceed the limits required by Part 3 when each of these elements is subjected to a horizontal specified live load of 0.1 kN applied in opposite directions in the in-plane direction of the guard so as to produce the most critical effect.
(5)The specified live loads required in Sentence (3) need not be considered to act simultaneously with the loads provided for in Sentences (1), (2), (6) and (7).
(6)The minimum specified live load applied vertically at the top of every required guard shall be 1.5 kN/m and need not be considered to act simultaneously with the horizontal specified live load provided for in Sentences (1), (3) and (7).
(7)Handrails and their supports shall be designed and constructed to withstand the following minimum specified live loads, which need not be considered to act simultaneously:
(a)0.9 kN applied at any point and in any direction for all handrails, and
(b)0.7 kN/m applied in any direction for handrails not located within dwelling units.
OBC Div. B 9.8.2.1. Stair Width
Open OBC Div. B 9.8.2.1. in the code viewer(1)Except as provided in Sentence (2) and Article 9.8.4.7., required exit stairs and public stairs serving buildings of residential occupancy shall have a width of not less than 900 mm.
(2)Exit stairs serving a single dwelling unit or a house with a secondary suite including their common spaces shall have a width of not less than 860 mm.
(3)Except as provided in Article 9.8.4.7., required exit stairs and public stairs serving buildings of other than residential occupancy shall have a width of not less than the greater of
(a)900 mm, or
(b)8 mm per person based on the occupant load limits specified in Table 3.1.17.1.
(4)Except as provided in Article 9.8.4.7., at least one stair between each floor level within a dwelling unit, and exterior stairs serving a single dwelling unit except required exit stairs, shall have a width of not less than 860 mm.