Canada · Permits & process

What are the building code requirements for retaining wall permits in Canada?

Retaining walls above a certain height threshold, typically 1.0 m to 1.2 m depending on jurisdiction, require a building permit and engineered design. Walls that retain soil adjacent to a building, driveway, or public area may require a permit regardless of height.

Retaining wall construction intersects building code, structural engineering, and municipal bylaw requirements. The building code and municipal bylaws address when a permit is required based on wall height and proximity to buildings or public areas, engineered design requirements for walls above the permit threshold, drainage and waterproofing behind the wall, guardrail requirements at the top of retaining walls where a fall hazard exists, and setback requirements from property lines.

What to check first

  • Retaining walls above a height threshold (typically 1.0 m to 1.2 m) require a building permit and engineered design.
  • Walls retaining soil near a building foundation may need a permit regardless of height.
  • Guards may be required at the top of retaining walls where a fall hazard exists.

Jurisdiction notes

National baseline

The NBC addresses structural and guard requirements for retaining walls, with permit thresholds typically set by municipal bylaws.

Municipal permit thresholds

The height at which a retaining wall requires a permit varies by municipality, commonly between 1.0 m and 1.2 m.

Engineering requirements

Retaining walls above the permit threshold typically require a design sealed by a professional engineer.

Not professional advice

CodeCan reports what the published building code says. It is not legal, engineering, or architectural advice, and it does not certify compliance. Building codes are adopted and amended provincially and enforced locally — always verify with your authority having jurisdiction (AHJ) before you build.

Work through it in this order

  1. Determine the retaining wall height and check the municipal permit threshold for the location.
  2. Confirm whether proximity to a building, driveway, or property line triggers additional requirements.
  3. Obtain engineered design if the wall exceeds the permit threshold or supports building loads.
  4. Verify drainage, waterproofing, and guard requirements for the retaining wall design.

Common questions

When does a retaining wall need a permit?

Most municipalities require a building permit for retaining walls above 1.0 m to 1.2 m in height, or when the wall retains soil near a building or public area.

Does a retaining wall need an engineer?

Retaining walls above the permit threshold typically require a design sealed by a professional engineer, including structural calculations and drainage details.

Is a guard required at the top of a retaining wall?

If the retaining wall creates a fall hazard above a certain height (typically 600 mm), a guard is required at the top to prevent falls.