National baseline
The NBC provides spatial separation tables that relate limiting distance, exposing building face area, and allowable unprotected openings to the required fire-resistance rating.
Canadian building code question
What are the building code requirements for building setbacks and property lines in Canada?
The NBC controls construction at property lines through spatial separation rules — limiting unprotected openings and requiring fire-resistance ratings for exposing building faces based on the distance from the property line, the building area, and the occupancy classification.
Building setbacks under the NBC are not zoning setbacks — they are spatial separation rules that govern how much of a building face can have unprotected openings and what fire-resistance rating the exposing building face must have, based on the distance to the property line or another building. These rules prevent fire spread between buildings and are independent of municipal zoning setbacks.
What to check first
- The NBC spatial separation rules limit unprotected openings and require fire-resistance ratings for exposing building faces based on property line distance.
- Building code setback requirements are independent of — and in addition to — municipal zoning setbacks.
- The allowable percentage of unprotected openings and the required fire-resistance rating depend on the building face area, the distance, and the occupancy.
Jurisdiction notes
Provincial adoption check
Provinces adopt the spatial separation rules with possible amendments. Municipal zoning setbacks are a separate layer that must also be satisfied.
Project-specific variables
The building face area, distance to property line, occupancy, sprinkler status, and whether the building is on both sides of the property line all affect the calculation.
Work through it in this order
- Determine the limiting distance from each exposing building face to the property line or centre line of a public way.
- Calculate the exposing building face area for each face.
- Use the NBC spatial separation tables to find the allowable percentage of unprotected openings and the required fire-resistance rating.
- Confirm whether sprinklering allows an increase in unprotected openings.
- Verify provincial adoption and coordinate with municipal zoning setback requirements.
Common questions
Are building code setbacks the same as zoning setbacks?
No. Building code spatial separation rules govern fire-resistance and unprotected openings based on property line distance. Zoning setbacks are a separate municipal requirement.
How do you calculate the allowable unprotected openings for a building face?
The NBC provides tables that relate the limiting distance, exposing building face area, and occupancy to the maximum allowable percentage of unprotected openings.
Can sprinklering allow more windows near a property line?
Yes, sprinklering can increase the allowable percentage of unprotected openings, but the exposing building face may still require a fire-resistance rating depending on the limiting distance.