Division B
Acceptable Solutions
Part 9 — Housing and Small Buildings
Section 9.12. Excavation
9.12.1. General
9.12.1.1. Removal of Topsoil and Organic Matter
1) 
The topsoil and vegetable matter in all unexcavated areas under a building shall be removed.
The topsoil and vegetable matter in all unexcavated areas under a building shall be removed. 2) In localities where termite infestation is known to be a problem, all stumps, roots and other wood debris shall be removed from the soil to a depth of not less than 300 mm in unexcavated areas under a building.
In localities where termite infestation is known to be a problem, all stumps, roots and other wood debris shall be removed from the soil to a depth of not less than 300 mm in unexcavated areas under a building. 3) The bottom of every excavation shall be free of all organic material.
The bottom of every excavation shall be free of all organic material.
9.12.1.2. Standing Water
1) Excavations shall be kept free of standing water.
Excavations shall be kept free of standing water.
9.12.1.3. Protection from Freezing
9.12.2. Depth
9.12.2.1. Excavation to Undisturbed Soil
9.12.2.2. Minimum Depth of Foundations
1) Except as provided in 
Sentences (4) to (7)
, the minimum depth of foundations below finished ground level shall conform to Table 9.12.2.2.
Sentences (4) to (7), the minimum depth of foundations below finished ground level shall conform to Table 9.12.2.2.
| Table 9.12.2.2. Minimum Depths of Foundations Forming part of Sentence 9.12.2.2.(1) | ||||
|
Type of Soil |
Minimum Depth of Foundation Containing Heated Basement or Crawl Space(1) |
Minimum Depth of Foundation Containing No Heated Space(2) | ||
|
Good Soil Drainage |
Poor Soil Drainage |
Good Soil Drainage |
Poor Soil Drainage |
|
| No limit | No limit | No limit | No limit | |
|
Coarse grained soils |
No limit | No limit | No limit | Below the depth of frost penetration |
| Silt | No limit | No limit |
Below the depth of frost penetration(3) |
Below the depth of frost penetration |
|
1.2 m (3 ft. 11 in.)(3) |
1.2 m (3 ft. 11 in.) |
1.2 m (3 ft. 11 in.) but not less than the depth of frost penetration(3) |
1.2 m (3 ft. 11 in.) but not less than the depth of frost penetration |
|
| Notes to Table 9.12.2.2.: | |
|
|
|
| (1) | Foundation not insulated to reduce heat loss through the footings. |
| (2) | Including foundations insulated to reduce heat loss through the footings. |
| (3) | Good soil drainage to not less than the depth of frost penetration. |
| (4) | See Appendix A. |
2) Where a foundation is insulated in a manner that will reduce heat flow to the soil beneath the footings, the foundation depth shall conform to that required for foundations containing no heated space. (See Appendix A.)
Where a foundation is insulated in a manner that will reduce heat flow to the soil beneath the footings, the foundation depth shall conform to that required for foundations containing no heated space. (See Appendix A.)3) The minimum depth of foundations for exterior concrete steps with more than 2 risers shall conform to Sentences (1), (2) and (5).
The minimum depth of foundations for exterior concrete steps with more than 2 risers shall conform to Sentences (1), (2) and (5). 4) Concrete steps with 1 and 2 risers are permitted to be laid on ground level.
Concrete steps with 1 and 2 risers are permitted to be laid on ground level.
5) The foundation depths required in Sentence (1) are permitted to be decreased where experience with local soil conditions shows that lesser depths are satisfactory, or where the foundation is designed for lesser depths.
The foundation depths required in Sentence (1) are permitted to be decreased where experience with local soil conditions shows that lesser depths are satisfactory, or where the foundation is designed for lesser depths.
6) The foundation depths required by Sentence (1) do not apply to foundations for
a) buildings
i) that are not of masonry or masonry veneer construction, and
ii) whose superstructure conforms to the requirements of the deformation resistance test in Z240.2.1, “Structural Requirements for Manufactured Homes,” or
b) accessory buildings
i) that are not of masonry or masonry veneer construction,
ii) not more than 1 storey in height,
iii) not more than 55 m2 in building area, and
iv) where the distance from finished ground to the underside of the floor joists is not more than 600 mm.
7) The foundation depths required by Sentence (1) do not apply to foundations for decks and other accessible exterior platforms
The foundation depths required by Sentence (1) do not apply to foundations for decks and other accessible exterior platformsa) of not more than 1 storey,
b) not more than 55 m2 in area,
c) where the distance from finished ground to the underside of
the joists is not more than 600 mm,
d) not supporting a roof, and
e) not attached to another structure, unless it can be demonstrated
that differential movement will not adversely affect the performance
of that structure.
8) Where decks or other accessible exterior platforms are supported on surface foundations supported on other than coarse-grained soil with good drainage or rock, access to the foundation positions to permit re-levelling of the platform shall be provided
Where decks or other accessible exterior platforms are supported on surface foundations supported on other than coarse-grained soil with good drainage or rock, access to the foundation positions to permit re-levelling of the platform shall be provideda) by passageways with a clear height under the platform of not
less than 600 mm and a width of not less than 600
mm, or
b) by installing the decking in a manner that allows easy removal.
9.12.3. Backfill
9.12.3.1. Placement of Backfill
1) Backfill shall be placed to avoid damaging the foundation wall, the drainage tile, externally applied thermal insulation and waterproofing or dampproofing of the wall.
Backfill shall be placed to avoid damaging the foundation wall, the drainage tile, externally applied thermal insulation and waterproofing or dampproofing of the wall.
9.12.3.2. Grading of Backfill
9.12.3.3. Deleterious Debris and Boulders
1) Backfill that is within 600 mm of the foundation shall be free of deleterious debris and boulders larger that 250 mm diam. (See Appendix A.)
Backfill that is within 600 mm of the foundation shall be free of deleterious debris and boulders larger that 250 mm diam. (See Appendix A.) 2) Except as provided in Sentence (3), backfill shall not contain pyritic material or material that is susceptible to ice lensing in concentrations that will damage the building to a degree that would adversely affect its stability or the performance of assemblies. (See A-9.4.4.4.(1) in Appendix A.)
Except as provided in Sentence (3), backfill shall not contain pyritic material or material that is susceptible to ice lensing in concentrations that will damage the building to a degree that would adversely affect its stability or the performance of assemblies. (See A-9.4.4.4.(1) in Appendix A.) 3) Backfill with material of any concentration that is susceptible to ice lensing is permitted where foundation walls are cast-in-place concrete, concrete block insulated on the exterior or concrete block protected from the backfill by a material
that serves as a slip plane. (See A-9.4.4.4.(1) in Appendix A.)
Backfill with material of any concentration that is susceptible to ice lensing is permitted where foundation walls are cast-in-place concrete, concrete block insulated on the exterior or concrete block protected from the backfill by a material
that serves as a slip plane. (See A-9.4.4.4.(1) in Appendix A.) 9.12.4. Trenches beneath Footings
9.12.4.1. Support of Footings
1) The soil in trenches beneath footings for sewers and watermains shall be compacted by tamping up to the
level of the footing base, or shall be filled with concrete having
a strength not less than 10 MPa to support the footing.
The soil in trenches beneath footings for sewers and watermains shall be compacted by tamping up to the
level of the footing base, or shall be filled with concrete having
a strength not less than 10 MPa to support the footing.