Canada · Roofs & rooftops

What are the building code requirements for roofing replacement in Canada?

Roof replacement must address structural capacity for the new roofing material, ice and water protection at eaves and valleys, attic ventilation preservation, and may require a permit depending on the scope. Adding layers of roofing material increases dead load and may not be permitted beyond code limits.

Roof replacement is a major maintenance project with code implications that are often overlooked. The structural capacity of the roof must support the new roofing material, especially when overlaying existing layers. Ice and water protection membrane requirements apply at eaves, valleys, and other vulnerable locations. Attic ventilation must be maintained during the replacement. Some municipalities require building permits for roof replacement, particularly when structural modifications or material changes are involved.

What to check first

  • Adding roofing layers increases dead load and may exceed structural capacity or the maximum number of permitted layers.
  • Ice and water protection membrane is required at eaves, valleys, and other vulnerable locations.
  • Attic ventilation must not be compromised during roofing replacement.

Jurisdiction notes

National baseline

The NBC sets structural load, ventilation, and roofing material requirements.

Climate considerations

Ice and water protection requirements vary by climate zone. Northern and coastal regions have additional considerations.

Municipal permits

Permit requirements for roofing replacement vary by municipality. Check local requirements before starting work.

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 whether the existing roofing will be removed or overlaid, and check the maximum permitted number of layers.
  2. Verify structural capacity for the chosen roofing material weight, especially if overlaying.
  3. Confirm ice and water protection requirements for the project location.
  4. Ensure attic ventilation is maintained and check municipal permit requirements.

Common questions

Do I need a permit for a roof replacement?

Permit requirements vary by municipality. Some require permits for all roofing work; others only for structural changes or material type changes.

How many layers of shingles are allowed?

The building code and manufacturer requirements typically limit the number of overlay layers. Check the applicable provision for your roofing material.

Is ice and water shield required?

Ice and water protection membrane is required at eaves, valleys, and other vulnerable locations in most Canadian climate zones.