Footings and Foundations
Application
(1)Except as provided in Articles 9.15.1.2. and 9.15.1.3., this Section applies to
- (a) concrete or unit masonry foundation walls and concrete footings not subject to surcharge (i) on stable soils with an allowable bearing pressure of 75 kPa or greater, and (ii) for buildings of wood-frame or masonry construction,
- (b) wood-frame foundation walls and wood or concrete footings not subject to surcharge (i) on stable soils with an allowable bearing pressure of 75 kPa or greater, and (ii) for buildings of wood-frame construction, and
- (c) flat insulating concrete form foundation walls and concrete footings not subject to surcharge (i) on stable soils with an allowable bearing pressure of 75 kPa or greater, and (ii) for buildings of light-frame or flat insulating concrete form construction that are not more than 2 storeys in building height, with a maximum floor-to-floor height of 3 m.
(2)Foundations for applications other than as described in Sentence (1) shall be designed in accordance with Section 9.4.
(3)Where a foundation is erected on filled ground, peat or sensitive clay, the footing sizes shall be designed in conformance with Section 4.2.
(4)For the purpose of Sentence (3), sensitive clay means the grain size of the majority of the particles is smaller than 0.002 mm, including leda clay.
(1)Buildings erected on permafrost shall have foundations designed by a designer competent in this field in accordance with the appropriate requirements of Part 4.
(1)Where the superstructure of a detached building conforms to the requirements of the deformation resistance test in CSA Z240.2.1, "Structural requirements for manufactured homes," the foundation shall be constructed in conformance with,
- (a) the remainder of this Section, or
- (b) CSA Z240.10.1, "Site preparation, foundation, and installation of buildings."
General
(1)Concrete block shall conform to CSA A165.1, "Concrete block masonry units," and shall have a compressive strength over the average net cross-sectional area of the block of not less than 15 MPa.
(2)Mortar, grout, mortar joints, corbelling and protection for unit masonry shall conform to Section 9.20.
(3)For concrete block foundation walls required to be reinforced,
- (a) mortar shall be Type S, conforming to CAN/CSA-A179, "Mortar and grout for unit masonry,"
- (b) grout shall be coarse, conforming to CAN/CSA-A179, "Mortar and grout for unit masonry," and
- (c) placement of grout shall conform to CAN/CSA-A371, "Masonry construction for buildings."
(1)Where pier type foundations are used, the piers shall be designed to support the applied loads from the superstructure.
(2)Where piers are used as a foundation system in a building of 1 storey in building height, the piers shall be installed to support the principal framing members and shall be spaced not more than 3.5 m apart along the framing, unless the piers and their footings are designed for larger spacings.
(3)The height of piers described in Sentence (2) shall not exceed 3 times their least dimension at the base of the pier.
(4)Where concrete block is used for piers described in Sentence (2), they shall be laid with cores placed vertically, and where the width of the building is 4.3 m or less, placed with their longest dimension at right angles to the longest dimension of the building.
(1)Foundations of wood-frame construction shall conform to
- (a) CSA S406, "Specification of permanent wood foundations for housing and small buildings," or
- (b) Part 4.
Footings
(1)Footings shall be provided under walls, pilasters, columns, piers, fireplaces and chimneys that bear on soil or rock, except that footings may be omitted under piers or monolithic concrete walls if the safe loadbearing capacity of the soil or rock is not exceeded.
(1)Footings shall rest on undisturbed soil, rock or compacted granular fill.
(2)Granular fill shall not contain pyritic material in a concentration that would adversely affect its stability or the performance of assemblies separating dissimilar environments.
(1)Except as provided in Sentence 9.15.3.4.(2), the minimum footing width or area requirements provided in Articles 9.15.3.4. to 9.15.3.7. shall apply to footings, where
- (a) the footings support (i) foundation walls of masonry, concrete, or flat insulating concrete form walls, (ii) above ground walls of masonry, flat insulating concrete form walls or light wood-frame construction, and (iii) floors and roofs of light wood-frame construction,
- (b) the span of supported joists does not exceed 4.9 m, and
- (c) the specified live load on any floor supported by the footing does not exceed 2.4 kPa.
(2)Except as provided in Sentence 9.15.3.4.(2), where the span of the supported joists exceeds 4.9 m, footings shall be designed in accordance with Section 4.2.
(3)Where the specified live load exceeds 2.4 kPa footings shall be designed in accordance with Section 4.2.
(1)Except as provided in Sentences (2) and (3) and in Articles 9.15.3.5. to 9.15.3.7., the minimum footing width or area shall comply with Table 9.15.3.4.
(2)Where the supported joist span exceeds 4.9 m in buildings with light wood-frame walls, floors and roofs, strip footing widths shall be determined according to
- (a) Section 4.2., or
- (b) the following formula: W = w × [ ∑ sjs / (storeys × 4.9)] where W = minimum footing width, w = minimum width of footings supporting joists not exceeding 4.9 m, as defined by Table 9.15.3.4., ∑ sjs = sum of the supported joist spans on each storey bearing on an exterior wall whose load is transferred to the footing, or sum of half of the supported joist spans on each storey bearing on both sides of an interior wall whose load is transferred to the footing, and storeys = number of storeys supported by the footing.
(3)Where a foundation rests on gravel, sand or silt in which the water table level is less than the width of the footings below the bearing surface,
- (a) the footing width for walls shall be not less than twice the width required by Sentences (1) and (2), and Articles 9.15.3.5. and 9.15.3.6., and
- (b) the footing area for columns shall be not less than twice the area required by Sentences (1) and (2) and Article 9.15.3.7.
| Number of Floors Supported | Minimum Width of Strip Footings, mm Supporting Exterior Walls | Minimum Width of Strip Footings, mm Supporting Interior Walls | Minimum Footing Area for Columns Spaced 3 m o.c., m2 |
|---|---|---|---|
| 1 | 0.40 | 0.75 | 1.0 |
(1)The strip footing widths for exterior walls shown in Table 9.15.3.4. shall be increased by
- (a) 65 mm for each storey of masonry veneer over wood-frame construction supported by the foundation wall,
- (b) 130 mm for each storey of masonry construction supported by the foundation wall, and
- (c) 150 mm for each storey of flat insulating concrete form wall construction supported by the foundation wall.
(1)The minimum strip footing widths for interior loadbearing masonry walls shown in Table 9.15.3.4. shall be increased by 100 mm for each storey of masonry construction supported by the footing.
(2)Footings for interior non-loadbearing masonry walls shall be not less than 200 mm wide for walls up to 5.5 m high and the width shall be increased by 100 mm for each additional 2.7 m of height.
(1)The footing area for column spacings other than shown in Table 9.15.3.4. shall be adjusted in proportion to the distance between columns.
(1)Footing thickness shall be not less than the greater of
- (a) 100 mm, or
- (b) the width of the projection of the footing beyond the supported element.
(1)Where step footings are used,
- (a) the vertical rise between horizontal portions shall not exceed 600 mm, and
- (b) the horizontal distance between risers shall be not less than 600 mm.
Foundation Walls
(1)Flat wall insulating concrete form units shall conform to CAN/ULC-S717.1, "Standard for Flat Wall Insulating Concrete Form (ICF) Units – Material Properties."
(1)Except as required in Sentence (2), the thickness of foundation walls made of unreinforced concrete block, concrete core in flat wall insulating concrete forms or solid concrete and subject to lateral earth pressure shall conform to Table 9.15.4.2.-A for walls not exceeding 3.0 m in unsupported height.
(2)The concrete core in flat insulating concrete form foundation walls shall be not less than the greater of
- (a) 150 mm, or
- (b) the thickness of the concrete in the wall above.
(2.1)Foundation walls made of flat insulating concrete form units shall be laterally supported at the top and at the bottom.
(3)The thickness and reinforcing of foundation walls made of reinforced concrete block and subject to lateral earth pressure shall conform to Table 9.15.4.2.-B and Sentences (4) to (7), where
- (a) the walls are laterally supported at the top,
- (b) average stable soils are encountered, and
- (c) wind loads on the exposed portion of the foundation are no greater than 0.70 kPa.
(4)For concrete block walls required to be reinforced, continuous vertical reinforcement shall
- (a) be provided at wall corners, wall ends, wall intersections, at changes in wall height, at the jambs of all openings and at movement joints,
- (b) extend from the top of the footing to the top of the foundation wall, and
- (c) where foundation walls are laterally supported at the top, have not less than 50 mm embedment into the footing, if the floor slab does not provide lateral support at the wall base.
(5)For concrete block walls required to be reinforced, a continuous horizontal bond beam containing not less than one 15M bar shall be installed
- (a) along the top of the wall,
- (b) at the sill and head of all openings greater than 1.20 m in width, and
- (c) at structurally connected floors.
(6)In concrete block walls required to be reinforced, all vertical bar reinforcement shall be installed along the centre line of the wall.
(7)In concrete block walls required to be reinforced, ladder- or truss-type lateral reinforcement not less than 3.8 mm in diameter (No. 9 ASWG) shall be installed in the bed joint of every second masonry course.
| Type of Foundation Wall | Minimum Thickness of Concrete or Concrete Block, mm | Maximum Height of Finish Ground Above Basement Floor or Crawl Space Ground Cover, m | Height of Foundation Wall Laterally Unsupported at the Top | Height of Foundation Wall Laterally Supported at the Top 3.0 m | 2.5 m | > 2.5 m and ≤ 2.75 m | > 2.75 m and ≤ 3.0 m |
|---|---|---|---|---|---|---|---|
| Solid concrete and concrete core in flat wall insulating concrete forms, 15 MPa min. strength | 150 | 0.8 | 1.5 | 1.5 | 1.4 | 1.2 | |
| 190 | 2.15 | 2.15 | 2.1 | 1.4 | |||
| 240 | 2.3 | 2.6 | 2.5 | 1.5 | |||
| 290 | 2.3 | 2.6 | 2.85 | ||||
| Solid concrete and concrete core in flat wall insulating concrete forms, 20 MPa min. strength | 150 | 0.8 | 1.8 | 1.6 | 1.6 | 1.2 | |
| 190 | 2.3 | 2.3 | 2.2 | 1.4 | |||
| 240 | 2.3 | 2.6 | 2.85 | 1.5 | |||
| 290 | 2.3 | 2.6 | 2.85 | ||||
| Unreinforced concrete block | 190 | 0.6 | 0.8 | — | — | ||
| 240 | 0.9 | 1.2 | See Table 9.15.4.2.-B | See Table 9.15.4.2.-B | |||
| 290 | 1.2 | 1.8 | See Table 9.15.4.2.-B | See Table 9.15.4.2.-B | |||
| 340 | 1.4 | 2.2 | — | — |
| Maximum Height of Finished Ground Above Basement Floor or Crawl Space Ground Cover, m | 190 mm Minimum Wall Thickness - 2.5 m | 190 mm Minimum Wall Thickness - 2.75 m | 190 mm Minimum Wall Thickness - 3.0 m | 240 mm Minimum Wall Thickness - 2.5 m | 240 mm Minimum Wall Thickness - 2.75 m | 240 mm Minimum Wall Thickness - 3.0 m |
|---|---|---|---|---|---|---|
| 0.8 | No reinforcement required | No reinforcement required | No reinforcement required | No reinforcement required | No reinforcement required | No reinforcement required |
| 1.0 | No reinforcement required | 1-15M at 1800 | 1-15M at 1800 | No reinforcement required | No reinforcement required | No reinforcement required |
| 1.2 | No reinforcement required | 1-15M at 1600 | 1-15M at 1600 | No reinforcement required | 1-20M at 2000 | 1-20M at 2000 |
| 1.4 | 1-15M at 1600 | 1-15M at 1600 | 1-15M at 1600 | No reinforcement required | 1-20M at 1800 | 1-20M at 1800 |
| 1.6 | 1-15M at 1400 | 1-15M at 1400 | 1-15M at 1400 | No reinforcement required | 1-20M at 1600 | 1-20M at 1600 |
| 1.8 | 1-15M at 1400 | 1-15M at 1400 | 1-15M at 1200 | No reinforcement required | 1-20M at 1600 | 1-20M at 1600 |
| 2.0 | 1-15M at 1200 | 1-15M at 1000 or 1-20M at 1200 | 2-15M at 1200 | 1-20M at 1600 | 1-20M at 1600 | 1-20M at 1600 |
| 2.2 | 2-15M at 1200 | 2-15M at 1000 | 2-15M at 1000 | 1-20M at 1400 | 1-20M at 1400 | 1-20M at 1400 |
| 2.4 | 2-15M at 1000 | 2-15M at 1000 | 2-15M at 800 | 1-20M at 1400 | 1-20M at 1400 | 1-20M at 1200 |
| 2.6 | n/a | 2-15M at 800 or 1-25M at 1000 | 2-15M at 800 or 1-25M at 1000 | n/a | 1-20M at 1000 | 1-20M at 1000 |
| 2.8 | n/a | n/a | 1-20M at 600 | n/a | n/a | 1-20M at 800 or 2-15M at 1000 |
| 3.0 | n/a | n/a | 1-20M at 400 or 1-25M at 600 | n/a | n/a | 2-15M at 800 |
(1)Sentences (2) to (4) pertain to lateral support for walls described in Sentence 9.15.4.2.(1).
(2)Foundation walls shall be considered to be laterally supported at the top if
- (a) such walls support a solid masonry superstructure or flat insulating concrete form wall,
- (b) the floor joists are embedded in the top of the foundation walls,
- (c) the floor system is anchored to the top of the foundation walls with anchor bolts, in which case the joists may run either parallel or perpendicular to the foundation walls, or
- (d) they extend from the footing to no more than 300 mm above the finished ground level and are backfilled on both sides such that the difference in elevation between the finished ground levels on either side of the wall is no more than 150 mm.
(3)Unless the wall around an opening is reinforced to withstand earth pressure, the portion of the foundation wall beneath an opening shall be considered laterally unsupported if
- (a) the opening is more than 1.2 m wide, or
- (b) the total width of the openings in the foundation wall constitutes more than 25% of the length of the wall.
(4)For the purposes of Sentence (3), the combined width of the openings shall be considered as a single opening if the average width is greater than the width of solid wall between them.
(5)Flat insulating concrete form foundation walls shall be considered to be laterally supported at the top if the floor joists are installed according to Article 9.20.17.5.
(1)Flat insulating concrete form foundation walls shall be considered to be laterally supported at the bottom where the foundation wall
- (a) supports backfill not more than 1.2 m in height,
- (b) is supported at the footing by a shear key and at the top by the ground floor framing, or
- (c) is dowelled to the footing with not less than (i) 15M bars spaced not more than 1.2 m o.c., or (ii) 10M bars spaced not more than 600 mm o.c.
(1)Horizontal reinforcement in flat insulating concrete form foundation walls shall
- (a) consist of (i) one 10M bar placed not more than 300 mm from the top of the wall, and (ii) 10M bars spaced not more than 600 mm o.c., and
- (b) be located (i) in the inside half of the wall section, and (ii) with a minimum cover of 30 mm from the inside face of the concrete.
(2)Vertical reinforcement in flat insulating concrete form foundation walls shall be
- (a) provided in accordance with (i) Table 9.15.4.5.-A for 150 mm walls, (ii) Table 9.15.4.5.-B for 190 mm walls, and (iii) Table 9.15.4.5.-C for 240 mm walls,
- (b) located in the inside half of the wall section with a minimum cover of 30 mm from the inside face of the concrete wall, and
- (c) where interrupted by wall openings, be placed not more than 600 mm from each side of the openings.
(3)Cold joints in flat insulating concrete form foundation walls shall be reinforced with at least one 15M bar spaced not more than 600 mm o.c. and embedded not less than 300 mm on both sides of the joint.
(4)Reinforcing around openings in flat insulating concrete form foundation walls shall comply with Article 9.20.17.3. or 9.20.17.4.
| Maximum Height of Finished Ground Above Finished Basement Floor, m | Maximum Unsupported Basement Wall Height 2.44 m | 2.75 m | 3.00 m |
|---|---|---|---|
| 1.35 | 10M at 400 mm o.c. | 10M at 400 mm o.c. | 10M at 400 mm o.c. |
| 1.60 | 10M at 400 mm o.c. | 10M at 380 mm o.c. | 10M at 380 mm o.c. |
| 2.00 | 10M at 380 mm o.c. | 10M at 380 mm o.c. | 10M at 380 mm o.c. |
| 2.20 | 10M at 250 mm o.c. | 10M at 250 mm o.c. | 10M at 250 mm o.c. |
| 2.35 | n/a | 10M at 250 mm o.c. | 10M at 250 mm o.c. |
| 2.60 | n/a | 10M at 250 mm o.c. | 10M at 250 mm o.c. |
| 3.00 | n/a | n/a | 10M at 250 mm o.c. |
| Maximum Height of Finished Ground Above Finished Basement Floor, m | Maximum Unsupported Basement Wall Height 2.44 m | 2.75 m | 3.00 m |
|---|---|---|---|
| 2.20 | none required | 10M at 400 mm o.c. | 10M at 400 mm o.c. |
| 2.35 | n/a | 10M at 300 mm o.c. | 10M at 300 mm o.c. |
| 2.60 | n/a | 10M at 300 mm o.c. | 15M at 400 mm o.c. |
| 3.00 | n/a | n/a | 15M at 400 mm o.c. |
| Maximum Height of Finished Ground Above Finished Basement Floor, m | Maximum Unsupported Basement Wall Height 2.44 m | 2.75 m | 3.00 m |
|---|---|---|---|
| 2.20 | none required | none required | none required |
| 2.60 | n/a | 15M at 400 mm o.c. | 15M at 400 mm o.c. |
| 3.00 | n/a | n/a | 15M at 400 mm o.c. |
(1)Exterior foundation walls shall extend not less than 150 mm above finished ground level.
(1)Where the top of a foundation wall is reduced in thickness to permit the installation of floor joists, the reduced section shall be not more than 350 mm high and not less than 90 mm thick.
(2)Where the top of a foundation wall is reduced in thickness to permit the installation of a masonry exterior facing, the reduced section shall be
- (a) not less than 90 mm thick, and
- (b) tied to the facing material with metal ties conforming to Sentence 9.20.9.4.(3) spaced not more than (i) 200 mm o.c. vertically, and (ii) 900 mm o.c. horizontally.
(3)The space between wall and facing described in Sentence (2) shall be filled with mortar.
(1)Corbelling of masonry foundation walls supporting cavity walls shall conform to Article 9.20.12.2.
(1)Crack control joints shall be provided in foundation walls more than 25 m long at intervals of not more than 15 m.
(2)Joints required in Sentence (1) shall be designed to resist moisture penetration and shall be keyed to prevent relative displacement of the wall portions adjacent to the joint.
(1)Interior masonry foundation walls not subject to lateral earth pressure shall conform to Section 9.20.
Support of Joists and Beams on Masonry Foundation Walls
(1)Except as permitted in Sentence (2), foundation walls of hollow masonry units supporting floor joists shall be capped with
- (a) not less than 50 mm of concrete,
- (b) solid masonry units that are 100% solid and not less than 50 mm high, or
- (c) semi-solid or hollow solid masonry units that have the top course completely filled with mortar, grout or concrete.
(2)Capping required in Sentence (1) need not be provided
- (a) in localities where termites are not known to occur,
- (b) when the joists are supported on a wood plate not less than 38 mm by 89 mm, and
- (c) when the siding overlaps the foundation wall not less than 12 mm.
(1)Not less than a 190 mm depth of solid masonry shall be provided beneath beams supported on masonry.
(2)Where the beam referred to in Sentence (1) is supported below the top of the foundation walls, the ends of such beams shall be protected from the weather.
(1)Pilasters shall be provided under beams that frame into unit masonry foundation walls 140 mm or less in thickness.
(2)Pilasters required in Sentence (1) shall be not less than 90 mm by 290 mm and shall be bonded or tied into the wall.
(3)The top 200 mm of pilasters required in Sentence (1) shall be solid masonry with the cells of hollow or semi-solid units filled with mortar, grout or concrete.
Parging and Finishing of Masonry Foundation Walls
(1)Concrete block foundation walls shall be parged on the exterior face below ground level as required in Section 9.13.
(1)Exterior surfaces of concrete block foundation walls above ground level shall have tooled joints, or shall be parged or otherwise suitably finished.
(1)All form ties shall be removed at least flush with the concrete surface.