Last updated
Values this chapter turns on
- minimum diameter of a round wood column
- 184 mm
- minimum diameter of a round wood column
- max load on a CGSB adjustable steel column
- 36 kN
- max load on a CGSB adjustable steel column
- minimum end bearing for beams on masonry
- 90 mm
- minimum end bearing for beams on masonry
- no openings this close to ICF wall corners
- 1,200 mm
- no openings this close to ICF wall corners
This chapter covers the vertical elements of a Part 9 building. That means posts and columns, masonry walls, flat insulating concrete form (ICF) walls, and the structural parts of chimneys and fireplaces. Most questions ask for a minimum size, a spacing, or the limit that sends you to Part 4.
Columns (9.17)
Section 9.17 applies to columns supporting beams that carry no more than 2 wood-frame floors. The joist length bearing on the beam may not exceed 5 m, and the live load may not exceed 2.4 kPa. Similar limits apply to deck columns, and carport roofs are also covered OBC Div. B 9.17.1.1.OBC Div. B 9.17.1.1. Application(1) This Section applies to columns used to support (a) beams carrying loads from not more than 2 wood-frame floors where (i) the supported length of joists bearing on such beams does not exceed 5 m, and (ii) the live load on any floor does not exceed 2.4 kPa, (See Table 4.1.5.3.) (b) beams or header joists carrying…. Outside those limits, the columns are designed to Part 4.
Columns sit centrally on a footing that meets 9.15. They must be fastened to the member they support and braced against racking. A deck column no more than 600 mm long that carries no superstructure is exempt from bracing OBC Div. B 9.17.2.2.OBC Div. B 9.17.2.2. Lateral Support(1) Columns shall be securely fastened to the supported member to reduce the likelihood of lateral differential movement between the column and the supported member. (See also Article 9.23.6.2.) (2) Except as permitted by Sentence (3), columns shall be laterally supported to resist racking (a) directly, or (b) by….
| Column type | Minimum |
|---|---|
| Steel pipe | 73 mm outside diameter, 4.76 mm wall (9.17.3.1.OBC Div. B 9.17.3.1. Size and Thickness(1) Except as permitted in Sentence (2), steel pipe columns shall have an outside diameter of not less than 73 mm and a wall thickness of not less than 4.76 mm. (2) Columns of sizes other than as specified in Sentence (1) are permitted to be used where the loadbearing capacities are shown to be adequate.) |
| Steel end plates | 100 x 100 x 6.35 mm. A top plate spans the full width of a wood beam (9.17.3.2.OBC Div. B 9.17.3.2. End Bearing Plates(1) Except as permitted in Sentence (2), steel columns shall be fitted with not less than 100 mm by 100 mm by 6.35 mm thick steel plates at each end, and where the column supports a wooden beam, the top plate shall extend across the full width of the beam. (2) The top plate required in Sentence (1) need not be…) |
| Wood, round | 184 mm diameter (9.17.4.1.OBC Div. B 9.17.4.1. Column Sizes(1) The width or diameter of a wood column shall be not less than the width of the supported member. (2) Except as provided in Article 9.35.4.2., columns shall be not less than 184 mm for round columns and 140 mm by 140 mm for rectangular columns, unless calculations are provided to show that lesser sizes are adequate.) |
| Wood, rectangular | 140 x 140 mm, and never narrower than the supported member |
| Unit masonry | 290 x 290 mm or 240 x 380 mm (9.17.5.2.OBC Div. B 9.17.5.2. Sizes(1) Unit masonry columns shall be not less than 290 mm by 290 mm or 240 mm by 380 mm in size.) |
| Concrete | 200 x 200 mm, or 230 mm diameter (9.17.6.2.OBC Div. B 9.17.6.2. Sizes(1) Concrete columns shall be not less than 200 mm by 200 mm for rectangular columns and 230 mm diam for circular columns.) |
Other column rules:
- Adjustable steel columns conform to CAN/CGSB-7.2 only where the imposed load is 36 kN or less. Above that, they are designed to Part 4 OBC Div. B 9.17.3.4.OBC Div. B 9.17.3.4. Design of Adjustable Steel Columns(1) Where the imposed load does not exceed 36 kN, adjustable steel columns shall conform to CAN/CGSB-7.2, "Adjustable Steel Columns." (2) Adjustable steel columns other than those described in Sentence (1) shall be designed in accordance with Part 4..
- Built-up wood columns use full-length members at least 38 mm thick. Fasten them with bolts of at least 9.52 mm at no more than 450 mm, or 76 mm nails at no more than 300 mm OBC Div. B 9.17.4.2.OBC Div. B 9.17.4.2. Materials(1) Wood columns shall be either solid, glued-laminated or built-up. (2) Built-up columns shall consist of not less than 38 mm thick full-length members (a) bolted together with not less than 9.52 mm diam bolts spaced not more than 450 mm o.c., or (b) nailed together with not less than 76 mm nails spaced not more than….
- Wood on concrete: separate a wood column from concrete in contact with the ground with polyethylene or Type S roll roofing.
Masonry walls (9.20)
Thickness OBC Div. B 9.20.6.1.OBC Div. B 9.20.6.1. Thickness of Exterior Walls(1) Masonry exterior walls, other than cavity walls, in 1-storey buildings and the top storeys of 2- and 3-storey buildings shall be not less than 140 mm thick, provided the walls are not more than 2.8 m high at the eaves and 4.6 m high at the peaks of gable ends. (2) The exterior walls of the bottom storeys of…:
- 140 mm in 1-storey buildings and in the top storey of 2- and 3-storey buildings. This holds only if the wall is no more than 2.8 m high at the eaves and 4.6 m at gable peaks.
- 190 mm in the bottom storey of a 2-storey building, and in the bottom 2 storeys of a 3-storey building.
- 90 mm minimum for each wythe.
Cavity walls need a cavity of 50 to 150 mm OBC Div. B 9.20.6.2.OBC Div. B 9.20.6.2. Cavity Walls(1) Cavity walls shall be made with not less than 90 mm wide units if the joints are raked and not less than 75 mm wide units if the joints are not raked. (2) The width of a cavity in a cavity wall shall be not less than 50 mm and not greater than 150 mm. (3) The minimum thickness of cavity walls above the supporting….
Veneer is solid units at least 70 mm thick, with a 25 mm air space over wood framing OBC Div. B 9.20.6.4.OBC Div. B 9.20.6.4. Masonry Veneer(1) Except for masonry veneer where each masonry unit is supported individually by the structural backing, masonry veneer shall consist of solid masonry units not less than 70 mm thick. (2) Veneer described in Sentence (1) over wood-frame walls shall have not less than a 25 mm air space behind the veneer. (3) Masonry….
Parapets may rise no more than 3 times their thickness above the roof OBC Div. B 9.20.6.5.OBC Div. B 9.20.6.5. Parapet Walls(1) The height of parapet walls above the adjacent roof surface shall be not more than 3 times the parapet wall thickness. (2) A parapet wall shall be solid masonry that extends from the top of the parapet wall to not less than 300 mm below the adjacent roof level. (3) Where semi-solid or hollow units are used in a….
Bearing on masonry OBC Div. B 9.20.8.3.OBC Div. B 9.20.8.3. Bearing of Beams and Joists(1) The bearing area under beams and joists shall be sufficient to carry the supported load. (2) In no case shall the minimum length of end bearing of beams supported on masonry be less than 90 mm. (3) The length of end bearing of floor, roof or ceiling joists supported on masonry shall be not less than 40 mm.:
- Beams need at least 90 mm of end bearing; joists need at least 40 mm.
- On a wall or wythe thinner than 190 mm, beams and columns sit on pilasters. Provide at least 190 mm of solid masonry or concrete under them OBC Div. B 9.20.8.4.OBC Div. B 9.20.8.4. Support of Beams and Columns(1) Beams and columns supported on masonry walls shall be supported on pilasters where the thickness of the masonry wall or wythe is less than 190 mm. (2) Not less than 190 mm depth of solid masonry or concrete shall be provided under the beam or column referred to in Sentence (1). (3) Pilasters required in Sentence….
- Hollow-unit walls carrying framing are capped with 50 mm of solid masonry, or have the top course filled. A 38 x 89 mm wood plate under roof framing is the exception OBC Div. B 9.20.8.1.OBC Div. B 9.20.8.1. Capping of Hollow Masonry Walls(1) Except as permitted in Sentence (2), loadbearing walls of hollow masonry units supporting roof or floor framing members shall be capped with not less than 50 mm of solid masonry or have the top course filled with concrete. (2) Capping required in Sentence (1) may be omitted where the roof framing is supported on a….
Bonding and ties OBC Div. B 9.20.9.3.OBC Div. B 9.20.9.3. Bonding(1) Where wythes are bonded together with masonry units, the bonding units shall comprise not less than 4% of the wall surface area. (2) Bonding units described in Sentence (1) shall be spaced not more than 600 mm vertically and horizontally in the case of brick masonry and 900 mm o.c. in the case of block or tile…:
- Bonding units make up at least 4% of the wall area and extend 90 mm into the next wythe.
- Rod ties in cavity walls go at no more than 900 mm horizontally and 400 mm vertically OBC Div. B 9.20.9.4.OBC Div. B 9.20.9.4. Tying(1) Where 2 or more wythes are tied together with metal ties of the individual rod type, the ties shall conform to the requirements in Sentences (3) to (6). (2) Other ties may be used where it can be shown that such ties provide walls that are at least as strong and as durable as those made with the individual rod….
Lateral support is the classic calculation OBC Div. B 9.20.10.1.OBC Div. B 9.20.10.1. Lateral Support Required(1) Masonry walls shall be laterally supported by floor or roof construction or by intersecting masonry walls or buttresses. (2) The spacing of supports required in Sentence (1) shall be not more than (a) 20 times the wall thickness for all loadbearing walls and exterior non-loadbearing walls, and (b) 36 times the…. Supports (floors, roofs, cross walls or buttresses) may be no farther apart than:
- 20 times the wall thickness, for loadbearing walls and exterior non-loadbearing walls;
- 36 times the thickness, for interior non-loadbearing walls.
For a cavity wall, the thickness is the greater of two-thirds of the sum of the wythes and the thicker wythe.
Flat ICF walls (9.20.17)
Above-grade flat ICF walls have a concrete core at least 140 mm thick, constant over the full height OBC Div. B 9.20.17.1.OBC Div. B 9.20.17.1. Thickness of Flat Insulating Concrete Form Walls(1) The thickness of concrete in flat insulating concrete form walls not in contact with the ground shall be (a) not less than 140 mm, and (b) constant for the entire height of the wall.. Reinforcement OBC Div. B 9.20.17.2.OBC Div. B 9.20.17.2. Reinforcement for Flat Insulating Concrete Form Walls(1) Horizontal reinforcement in above-grade flat insulating concrete form walls shall (a) consist of (i) one 10 M bar placed not more than 300 mm from the top of the wall, and (ii) 10 M bars spaced not more than 600 mm o.c., and (b) be placed in the middle third of the wall section. (2) Vertical reinforcement in…:
- Horizontal: one 10M bar within 300 mm of the top, then 10M at 600 mm.
- Vertical: 10M at 400 mm.
- Both go in the middle third of the wall.
Openings OBC Div. B 9.20.17.4.OBC Div. B 9.20.17.4. Openings in Loadbearing Flat Insulating Concrete Form Walls(1) No openings shall occur within 1,200 mm of interior and exterior corners of exterior loadbearing flat insulating concrete form walls. (2) In loadbearing flat insulating concrete form walls, lintels shall be provided over all openings wider than 900 mm. (3) Lintels described in Sentence (2) shall be constructed in…:
- No openings within 1,200 mm of the corners of exterior loadbearing ICF walls.
- Lintels are required over openings wider than 900 mm.
- Over openings wider than 1,200 mm, lintels also need 10M stirrups.
Table 9.20.17.4.-AOBC Div. B Table 9.20.17.4-A. Maximum Allowable Clear Spans for Lintels in Flat ICF Walls (1-10M Bottom Bar) for Supporting Light-Frame Roof OnlyTable 9.20.17.4-A Maximum Allowable Clear Spans for Lintels in Flat ICF Walls (1-10M Bottom Bar) for Supporting Light-Frame Roof Only Forming Part of Sentences 9.3.2.8.(1) and 9.20.17.4.(3) Minimum Lintel Thickness, mm | Minimum Lintel Depth, mm | Maximum Ground Snow Load, 1.50 kN/m² | Maximum Ground Snow Load, 3.33… gives the maximum lintel clear span with one 10M bottom bar. Read it in this order:
- The part of the table (roof only, or ICF second storey plus roof).
- The lintel thickness and depth.
- The ground snow load column (1.50 or 3.33 kN/m²).
Linear interpolation is permitted between snow loads and between depths.
Roof framing on ICF walls is fixed to top plates. The plates are anchored with bolts of at least 12.7 mm, at no more than 1,200 mm and embedded 100 mm OBC Div. B 9.20.17.6.OBC Div. B 9.20.17.6. Anchoring of Roof Framing to Top of Flat Insulating Concrete Form Walls(1) Roof framing supported on the top of flat insulating concrete form walls shall be fixed to the top plates, which shall be anchored to the wall with anchor bolts (a) not less than 12.7 mm in diameter, and (b) spaced not more than 1,200 mm o.c. (2) The anchor bolts described in Sentence (1) shall be placed in the….
Chimneys and fireplaces
The structural rules for chimneys are short:
- Footings for masonry and concrete chimneys and fireplaces follow Section 9.15 (9.21.4.3.OBC Div. B 9.21.4.3. Footings(1) Footings for masonry chimneys and concrete chimneys shall conform to Section 9.15., 9.22.1.3.OBC Div. B 9.22.1.3. Footings(1) Footings for masonry and concrete fireplaces shall conform to Section 9.15.).
- Chimney walls are solid masonry units at least 70 mm thick OBC Div. B 9.21.4.8.OBC Div. B 9.21.4.8. Wall Thickness(1) The walls of a masonry chimney shall be built of solid masonry units not less than 70 mm thick..
- A chimney must be braced to Subsection 4.3.2 for wind, unless two conditions are both met: no horizontal outside dimension is under 400 mm, and the chimney rises no more than 3.6 m above the roof or wall it is part of OBC Div. B 9.21.4.5.OBC Div. B 9.21.4.5. Lateral Stability(1) Except as provided in Sentence (2), chimneys shall be braced in accordance with Subsection 4.3.2. to provide lateral stability under wind loads. (2) A chimney need not be laterally braced provided (a) no horizontal outside dimension is less than 400 mm, and (b) the chimney extends not more than 3.6 m above a roof….
- Joists or beams may bear on masonry walls that enclose flues only if at least 290 mm of solid masonry separates them from the flue OBC Div. B 9.21.5.3.OBC Div. B 9.21.5.3. Support of Joists or Beams(1) Joists or beams may be supported on masonry walls which enclose chimney flues provided the combustible members are separated from the flue by not less than 290 mm of solid masonry..
The fire chamber floor and hearth sit on a reinforced concrete slab. It is at least 100 mm thick at its supports and, if cantilevered, at least 50 mm at the free edge. A raised hearth (opening at least 200 mm above a combustible floor) may instead bear on that floor under the CSA A405 conditions OBC Div. B 9.22.5.2.OBC Div. B 9.22.5.2. Support of Hearth(1) Except as permitted in Sentence (2), the fire chamber floor and hearth shall be supported on a reinforced concrete slab not less than 100 mm thick at its supports and, if cantilevered, not less than 50 mm thick at its unsupported edge. (2) A hearth for a fireplace with an opening raised not less than 200 mm from a….
Chapter review
Chapter at a glance
One line per section: the idea to carry into the exam. Then the answers that most often catch candidates out.
- Columns (9.17)
Section 9.17 applies to columns supporting beams that carry no more than 2 wood-frame floors.
- Masonry walls (9.20)
Cavity walls need a cavity of 50 to 150 mm.
- Flat ICF walls (9.20.17)
Above-grade flat ICF walls have a concrete core at least 140 mm thick, constant over the full height.
- Chimneys and fireplaces
The fire chamber floor and hearth sit on a reinforced concrete slab.
Practice this chapter
Questions on Columns, masonry, chimneys and fireplaces (Part 9), in the exam format, every answer explained and cited to its article. Sign in to start; a free account gets the free questions.
Code cited in this chapter
Based on the official 2024 Building Code Compendium on ontario.ca.
© King's Printer for Ontario, 2024. Reproduced with permission.
OBC Div. B 9.17.1.1. Application
Open OBC Div. B 9.17.1.1. in the code viewer(1)This Section applies to columns used to support
(a)beams carrying loads from not more than 2 wood-frame floors where
(i)the supported length of joists bearing on such beams does not exceed 5 m, and
(ii)the live load on any floor does not exceed 2.4 kPa, (See Table 4.1.5.3.)
(b)beams or header joists carrying loads from not more than 2 levels of wood-frame balconies, decks or other accessible exterior platforms, or 1 level plus the roof, where
(i)the supported length of joists bearing on such beams or joists does not exceed 5 m,
(ii)the sum of the specified snow and occupancy loads does not exceed 4.8 kPa for the determination of load on platform-type constructions, and (See Sentence 9.4.2.3.(1))
(iii)the platform serves only a single suite of residential occupancy, or
(c)carport roofs. (See Section 9.35.)
(2)Columns for applications other than as described in Sentence (1) shall be designed in accordance with Part 4.
OBC Div. B 9.17.2.2. Lateral Support
Open OBC Div. B 9.17.2.2. in the code viewer(1)Columns shall be securely fastened to the supported member to reduce the likelihood of lateral differential movement between the column and the supported member. (See also Article 9.23.6.2.)
(2)Except as permitted by Sentence (3), columns shall be laterally supported to resist racking
(a)directly, or
(b)by connection to the supported members. (See Note A-9.17.2.2.(2))
(3)Columns need not be provided with lateral support as described in Sentence (2), where
(a)the length of the columns are not more than 600 mm measured from the finished ground to the underside of the supported member, and
(b)the columns support a deck with no superstructure.
OBC Div. B 9.17.3.1. Size and Thickness
Open OBC Div. B 9.17.3.1. in the code viewer(1)Except as permitted in Sentence (2), steel pipe columns shall have an outside diameter of not less than 73 mm and a wall thickness of not less than 4.76 mm.
(2)Columns of sizes other than as specified in Sentence (1) are permitted to be used where the loadbearing capacities are shown to be adequate.
OBC Div. B 9.17.3.2. End Bearing Plates
Open OBC Div. B 9.17.3.2. in the code viewer(1)Except as permitted in Sentence (2), steel columns shall be fitted with not less than 100 mm by 100 mm by 6.35 mm thick steel plates at each end, and where the column supports a wooden beam, the top plate shall extend across the full width of the beam.
(2)The top plate required in Sentence (1) need not be provided where a column supports a steel beam and provision is made for the attachment of the column to the beam
OBC Div. B 9.17.4.1. Column Sizes
Open OBC Div. B 9.17.4.1. in the code viewer(1)The width or diameter of a wood column shall be not less than the width of the supported member.
(2)Except as provided in Article 9.35.4.2., columns shall be not less than 184 mm for round columns and 140 mm by 140 mm for rectangular columns, unless calculations are provided to show that lesser sizes are adequate.
OBC Div. B 9.17.5.2. Sizes
Open OBC Div. B 9.17.5.2. in the code viewer(1)Unit masonry columns shall be not less than 290 mm by 290 mm or 240 mm by 380 mm in size.
OBC Div. B 9.17.6.2. Sizes
Open OBC Div. B 9.17.6.2. in the code viewer(1)Concrete columns shall be not less than 200 mm by 200 mm for rectangular columns and 230 mm diam for circular columns.
OBC Div. B 9.17.3.4. Design of Adjustable Steel Columns
Open OBC Div. B 9.17.3.4. in the code viewer(1)Where the imposed load does not exceed 36 kN, adjustable steel columns shall conform to CAN/CGSB-7.2, "Adjustable Steel Columns."
(2)Adjustable steel columns other than those described in Sentence (1) shall be designed in accordance with Part 4.
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OBC Div. B 9.17.4.2. Materials
Open OBC Div. B 9.17.4.2. in the code viewer(1)Wood columns shall be either solid, glued-laminated or built-up.
(2)Built-up columns shall consist of not less than 38 mm thick full-length members
(a)bolted together with not less than 9.52 mm diam bolts spaced not more than 450 mm o.c., or
(b)nailed together with not less than 76 mm nails spaced not more than 300 mm o.c.
(3)Glued-laminated columns shall conform to Section 4.3.
OBC Div. B 9.20.6.1. Thickness of Exterior Walls
Open OBC Div. B 9.20.6.1. in the code viewer(1)Masonry exterior walls, other than cavity walls, in 1-storey buildings and the top storeys of 2- and 3-storey buildings shall be not less than 140 mm thick, provided the walls are not more than 2.8 m high at the eaves and 4.6 m high at the peaks of gable ends.
(2)The exterior walls of the bottom storeys of 2-storey buildings, and exterior walls of the bottom 2 storeys of 3-storey buildings shall be not less than 190 mm thick.
(3)In exterior walls composed of more than one wythe, each wythe shall be not less than 90 mm thick.
OBC Div. B 9.20.6.2. Cavity Walls
Open OBC Div. B 9.20.6.2. in the code viewer(1)Cavity walls shall be made with not less than 90 mm wide units if the joints are raked and not less than 75 mm wide units if the joints are not raked.
(2)The width of a cavity in a cavity wall shall be not less than 50 mm and not greater than 150 mm.
(3)The minimum thickness of cavity walls above the supporting base shall be 230 mm for the top 7.6 m and 330 mm for the remaining portion, except that where 75 mm wide units are used, the wall height above the top of the foundation wall shall not exceed 6 m.
OBC Div. B 9.20.6.4. Masonry Veneer
Open OBC Div. B 9.20.6.4. in the code viewer(1)Except for masonry veneer where each masonry unit is supported individually by the structural backing, masonry veneer shall consist of solid masonry units not less than 70 mm thick.
(2)Veneer described in Sentence (1) over wood-frame walls shall have not less than a 25 mm air space behind the veneer.
(3)Masonry veneer less than 90 mm thick shall have unraked joints.
(4)Masonry veneer shall conform to Subsection 4.3.2. where the masonry units are required to be individually supported by the structural backing.
OBC Div. B 9.20.6.5. Parapet Walls
Open OBC Div. B 9.20.6.5. in the code viewer(1)The height of parapet walls above the adjacent roof surface shall be not more than 3 times the parapet wall thickness.
(2)A parapet wall shall be solid masonry that extends from the top of the parapet wall to not less than 300 mm below the adjacent roof level.
(3)Where semi-solid or hollow units are used in a parapet wall, the cells of those units shall be filled with mortar, grout or concrete.
OBC Div. B 9.20.8.3. Bearing of Beams and Joists
Open OBC Div. B 9.20.8.3. in the code viewer(1)The bearing area under beams and joists shall be sufficient to carry the supported load.
(2)In no case shall the minimum length of end bearing of beams supported on masonry be less than 90 mm.
(3)The length of end bearing of floor, roof or ceiling joists supported on masonry shall be not less than 40 mm.
OBC Div. B 9.20.8.4. Support of Beams and Columns
Open OBC Div. B 9.20.8.4. in the code viewer(1)Beams and columns supported on masonry walls shall be supported on pilasters where the thickness of the masonry wall or wythe is less than 190 mm.
(2)Not less than 190 mm depth of solid masonry or concrete shall be provided under the beam or column referred to in Sentence (1).
(3)Pilasters required in Sentence (1) shall be bonded or tied to masonry walls.
(4)Concrete pilasters required in Sentence (1) shall be not less than 50 mm by 300 mm.
(5)Unit masonry pilasters required in Sentence (1) shall be not less than 100 mm by 290 mm.
OBC Div. B 9.20.8.1. Capping of Hollow Masonry Walls
Open OBC Div. B 9.20.8.1. in the code viewer(1)Except as permitted in Sentence (2), loadbearing walls of hollow masonry units supporting roof or floor framing members shall be capped with not less than 50 mm of solid masonry or have the top course filled with concrete.
(2)Capping required in Sentence (1) may be omitted where the roof framing is supported on a wood plate not less than 38 mm by 89 mm.
OBC Div. B 9.20.9.3. Bonding
Open OBC Div. B 9.20.9.3. in the code viewer(1)Where wythes are bonded together with masonry units, the bonding units shall comprise not less than 4% of the wall surface area.
(2)Bonding units described in Sentence (1) shall be spaced not more than 600 mm vertically and horizontally in the case of brick masonry and 900 mm o.c. in the case of block or tile.
(3)Units described in Sentence (1) shall extend not less than 90 mm into adjacent wythes.
OBC Div. B 9.20.9.4. Tying
Open OBC Div. B 9.20.9.4. in the code viewer(1)Where 2 or more wythes are tied together with metal ties of the individual rod type, the ties shall conform to the requirements in Sentences (3) to (6).
(2)Other ties may be used where it can be shown that such ties provide walls that are at least as strong and as durable as those made with the individual rod type.
(3)Metal ties of the individual rod type shall
(a)be corrosion-resistant,
(b)have a minimum cross-sectional area of not less than 17.8 mm², and
(c)have not less than a 50 mm portion bent at right angles at each end.
(4)Metal ties of the individual rod type shall
(a)extend from within 25 mm of the outer face of the wall to within 25 mm of the inner face of the wall,
(b)be completely embedded in mortar except for the portion exposed in cavity walls, and
(c)be staggered from course to course.
(5)Where 2 or more wythes in walls other than cavity walls and masonry veneer/masonry backing walls are tied together with metal ties of the individual rod type, the space between wythes shall be completely filled with mortar.
(6)Ties described in Sentence (5) shall be
(a)located within 300 mm of openings and spaced not more than 900 mm apart around openings, and
(b)spaced not more than 900 mm apart horizontally and 460 mm apart vertically at other locations.
(7)Except as required in Sentences (8) and (9), where the inner and outer wythes of cavity walls are tied with individual wire ties, the ties shall be spaced not more than 900 mm apart horizontally and 400 mm apart vertically.
(8)Within 100 mm of the bottom of each floor or roof assembly where the cavity extends below the assemblies, the ties described in Sentence (7) shall be spaced not more than 600 mm apart horizontally.
(9)Within 300 mm of any openings, the ties described in Sentence (7) shall be spaced not more than 900 mm apart.
OBC Div. B 9.20.10.1. Lateral Support Required
Open OBC Div. B 9.20.10.1. in the code viewer(1)Masonry walls shall be laterally supported by floor or roof construction or by intersecting masonry walls or buttresses.
(2)The spacing of supports required in Sentence (1) shall be not more than
(a)20 times the wall thickness for all loadbearing walls and exterior non-loadbearing walls, and
(b)36 times the wall thickness for interior non-loadbearing walls.
(3)In applying Sentence (2), the thickness of cavity walls shall be taken as the greater of
(a)two-thirds of the sum of the thicknesses of the wythes, or
(b)the thickness of the thicker wythe.
(4)Floor and roof structural elements providing lateral support for walls as required in Sentence (1) shall be constructed to transfer lateral loads to walls or buttresses approximately at right angles to the laterally supported walls.
OBC Div. B 9.20.17.1. Thickness of Flat Insulating Concrete Form Walls
Open OBC Div. B 9.20.17.1. in the code viewer(1)The thickness of concrete in flat insulating concrete form walls not in contact with the ground shall be
(a)not less than 140 mm, and
(b)constant for the entire height of the wall.
OBC Div. B 9.20.17.2. Reinforcement for Flat Insulating Concrete Form Walls
Open OBC Div. B 9.20.17.2. in the code viewer(1)Horizontal reinforcement in above-grade flat insulating concrete form walls shall
(a)consist of
(i)one 10 M bar placed not more than 300 mm from the top of the wall, and
(ii)10 M bars spaced not more than 600 mm o.c., and
(b)be placed in the middle third of the wall section.
(2)Vertical reinforcement in above-grade flat insulating concrete form walls shall
(a)consist of 10 M bars spaced not more than 400 mm o.c., and
(b)be placed in the middle third of the wall section.
(3)Vertical reinforcement required by Sentence (2) and interrupted by wall openings shall be placed not more than 600 mm from each side of the opening.
OBC Div. B 9.20.17.4. Openings in Loadbearing Flat Insulating Concrete Form Walls
Open OBC Div. B 9.20.17.4. in the code viewer(1)No openings shall occur within 1,200 mm of interior and exterior corners of exterior loadbearing flat insulating concrete form walls.
(2)In loadbearing flat insulating concrete form walls, lintels shall be provided over all openings wider than 900 mm.
(3)Lintels described in Sentence (2) shall be constructed in accordance with Span Table 9.20.17.4.-A, 9.20.17.4.-B or 9.20.17.4.-C.
(4)Lintels described in Sentence (2) over openings wider than 1,200 mm shall be reinforced for shear with 10 M stirrups at a maximum spacing of half the distance from the bottom reinforcing bar to the top of the lintel.
OBC Div. B Table 9.20.17.4-A. Maximum Allowable Clear Spans for Lintels in Flat ICF Walls (1-10M Bottom Bar) for Supporting Light-Frame Roof Only
Open OBC Div. B Table 9.20.17.4-A. in the code viewerTable 9.20.17.4-A Maximum Allowable Clear Spans for Lintels in Flat ICF Walls (1-10M Bottom Bar) for Supporting Light-Frame Roof Only Forming Part of Sentences 9.3.2.8.(1) and 9.20.17.4.(3) Minimum Lintel Thickness, mm | Minimum Lintel Depth, mm | Maximum Ground Snow Load, 1.50 kN/m² | Maximum Ground Snow Load, 3.33 kN/m² 140 | 200 | 1.41 | 1.18 140 | 300 | 1.78 | 1.50 140 | 400 | 2.08 | 1.75 140 | 500 | 2.33 | 1.97 140 | 600 | 2.55 | 2.16 150 | 200 | 1.41 | 1.18 150 | 300 | 1.78 | 1.50 150 | 400 | 2.08 | 1.75 150 | 500 | 2.33 | 1.97 150 | 600 | 2.54 | 2.15 160 | 200 | 1.41 | 1.18 160 | 300 | 1.78 | 1.50 160 | 400 | 2.07 | 1.75 160 | 500 | 2.32 | 1.96 160 | 600 | 2.53 | 2.15 190 | 200 | 1.41 | 1.19 190 | 300 | 1.78 | 1.50 190 | 400 | 2.06 | 1.74 190 | 500 | 2.30 | 1.95 190 | 600 | 2.51 | 2.13 200 | 200 | 1.41 | 1.19 200 | 300 | 1.77 | 1.49 200 | 400 | 2.06 | 1.74 200 | 500 | 2.30 | 1.95 200 | 600 | 2.50 | 2.13 240 | 200 | 1.41 | 1.19 240 | 300 | 1.76 | 1.49 240 | 400 | 2.04 | 1.73 240 | 500 | 2.27 | 1.93 240 | 600 | 2.47 | 2.11 Table 9.20.17.4-A (continued) — Maximum Allowable Clear Spans for Lintels in Flat ICF Walls (1-10M Bottom Bar) for Supporting ICF Second Storey and Light-Frame Roof Minimum Lintel Thickness, mm | Minimum Lintel Depth, mm | Maximum Ground Snow Load, 1.50 kN/m² | Maximum Ground Snow Load, 3.33 kN/m² 140 | 200 | 1.03 | 0.93 140 | 300 | 1.30 | 1.18 140 | 400 | 1.53 | 1.38 140 | 500 | 1.72 | 1.56 140 | 600 | 1.89 | 1.71 150 | 200 | 1.02 | 0.92 150 | 300 | 1.29 | 1.17 150 | 400 | 1.51 | 1.37 150 | 500 | 1.70 | 1.54 150 | 600 | 1.87 | 1.70 160 | 200 | 1.01 | 0.91 160 | 300 | 1.28 | 1.16 160 | 400 | 1.50 | 1.36 160 | 500 | 1.68 | 1.53 160 | 600 | 1.85 | 1.68 190 | 200 | 0.98 | 0.89 190 | 300 | 1.24 | 1.13 190 | 400 | 1.45 | 1.32 190 | 500 | 1.63 | 1.49 190 | 600 | 1.78 | 1.63 200 | 200 | 0.97 | 0.89 200 | 300 | 1.23 | 1.12 200 | 400 | 1.43 | 1.31 200 | 500 | 1.61 | 1.48 200 | 600 | 1.77 | 1.62 240 | 200 | 0.94 | 0.86 240 | 300 | 1.18 | 1.09 240 | 400 | 1.38 | 1.27 240 | 500 | 1.55 | 1.43 240 | 600 | 1.70 | 1.56 Notes to Table 9.20.17.4.-A: (1) Deflection criteria is L/240, where “L” is the clear span of the lintel. (2) Linear interpolation is permitted between ground snow loads and between lintel depths. (3) 10 M stirrups are required at a maximum d/2 spacing for spans greater than 1,200 mm, where “d” is the distance from the top of the lintel to the level of the bottom reinforcing bar in the lintel.
OBC Div. B 9.20.17.6. Anchoring of Roof Framing to Top of Flat Insulating Concrete Form Walls
Open OBC Div. B 9.20.17.6. in the code viewer(1)Roof framing supported on the top of flat insulating concrete form walls shall be fixed to the top plates, which shall be anchored to the wall with anchor bolts
(a)not less than 12.7 mm in diameter, and
(b)spaced not more than 1,200 mm o.c.
(2)The anchor bolts described in Sentence (1) shall be placed in the centre of the flat insulating concrete form wall and shall be embedded no less than 100 mm into the concrete.
(3)Attachment of roof framing to wood top plates shall be in accordance with Table 9.23.3.4.
OBC Div. B 9.21.4.3. Footings
Open OBC Div. B 9.21.4.3. in the code viewer(1)Footings for masonry chimneys and concrete chimneys shall conform to Section 9.15.
OBC Div. B 9.22.1.3. Footings
Open OBC Div. B 9.22.1.3. in the code viewer(1)Footings for masonry and concrete fireplaces shall conform to Section 9.15.
OBC Div. B 9.21.4.8. Wall Thickness
Open OBC Div. B 9.21.4.8. in the code viewer(1)The walls of a masonry chimney shall be built of solid masonry units not less than 70 mm thick.
OBC Div. B 9.21.4.5. Lateral Stability
Open OBC Div. B 9.21.4.5. in the code viewer(1)Except as provided in Sentence (2), chimneys shall be braced in accordance with Subsection 4.3.2. to provide lateral stability under wind loads.
(2)A chimney need not be laterally braced provided
(a)no horizontal outside dimension is less than 400 mm, and
(b)the chimney extends not more than 3.6 m above a roof or the masonry wall of which it forms a part. (See Note A-9.21.4.5.(2))
OBC Div. B 9.21.5.3. Support of Joists or Beams
Open OBC Div. B 9.21.5.3. in the code viewer(1)Joists or beams may be supported on masonry walls which enclose chimney flues provided the combustible members are separated from the flue by not less than 290 mm of solid masonry.
OBC Div. B 9.22.5.2. Support of Hearth
Open OBC Div. B 9.22.5.2. in the code viewer(1)Except as permitted in Sentence (2), the fire chamber floor and hearth shall be supported on a reinforced concrete slab not less than 100 mm thick at its supports and, if cantilevered, not less than 50 mm thick at its unsupported edge.
(2)A hearth for a fireplace with an opening raised not less than 200 mm from a combustible floor is permitted to be supported on that floor provided the requirements of Clauses 5.3.6.5. to 5.3.6.7. of CAN/CSA-A405-M, "Design and Construction of Masonry Chimneys and Fireplaces," are followed.