Canadian building code question

What are the building code requirements for frost depth and footings in Canada?

Footings must extend below the frost penetration depth for the project location, with minimum sizes based on building loads, soil bearing capacity, and construction type. Frost depth values are location-specific and published in the NBC climatic data tables or local supplements.

Foundation depth and footing design are fundamental structural requirements that protect buildings from frost heave. The code requires footings to be placed below the frost line, with dimensions based on soil bearing capacity and building loads. Getting the frost depth wrong can lead to heave, settlement, and structural damage that is extremely expensive to repair.

What to check first

  • Footings must be placed below the frost penetration depth, which varies by location across Canada.
  • Minimum footing sizes depend on the number of storeys, soil bearing capacity, and whether the building is load-bearing masonry or frame construction.
  • Frost-protected shallow foundations are an alternative in some conditions, with specific insulation and drainage requirements.

Jurisdiction notes

National baseline

Use NBC climatic data tables for design frost depth and the Part 9 footing tables for minimum sizes based on building loads and soil conditions.

Province and municipal data

Some municipalities publish local frost depth values that may differ from the NBC tables. Confirm with the local authority having jurisdiction.

Alternative foundations

Frost-protected shallow foundations, helical piles, and other systems have specific code provisions and may require engineered design.

Work through it in this order

  1. Determine the frost penetration depth for the project location using NBC climatic data or local municipal data.
  2. Identify the soil bearing capacity and building load conditions to select minimum footing dimensions.
  3. Verify whether a frost-protected shallow foundation is permitted as an alternative for the building type and location.
  4. Check provincial or municipal amendments that may affect minimum foundation depth or footing size.

Common questions

Where do I find the frost depth for my project location?

The NBC climatic data tables provide design frost depth values by location. Some municipalities also publish local values that may supersede the NBC data.

Can I use a frost-protected shallow foundation instead of deep footings?

In some conditions, yes. The code allows frost-protected shallow foundations with specific insulation and drainage requirements. Verify whether your building type and location qualify.

What soil bearing capacity should I use if I don't have a geotechnical report?

The NBC provides presumptive bearing capacity values for common soil types in Part 9. For Part 3 buildings or unusual conditions, a geotechnical report is typically required.