National baseline
Start with the NBC interior finish tables that specify maximum flame spread and smoke developed values by building location and occupancy.
Canadian building code question
What are the building code requirements for interior finish and flame spread in Canada?
The NBC limits flame spread ratings and smoke developed classifications for interior wall, ceiling, and floor finishes based on the location within the building. Exit enclosures have the strictest limits, followed by corridors, then rooms. Requirements depend on occupancy, sprinkler status, and building height.
Interior finish requirements control fire growth and smoke production to give occupants time to evacuate. The code assigns maximum flame spread ratings and smoke developed classifications by location — exits are the most restrictive because they must remain tenable during evacuation. Using the wrong material in a high-restriction location is a common code deficiency that can require costly rework.
What to check first
- Exit enclosures (stairwells, exit corridors) have the lowest allowable flame spread ratings and smoke developed classifications.
- Flame spread rating and smoke developed classification are determined by CAN/ULC-S102 testing — the manufacturer must provide tested values.
- Sprinkler status and building height can modify the flame spread limits for certain locations.
Jurisdiction notes
Province and edition check
Some provinces amend interior finish requirements for specific occupancies or add restrictions for high-rise buildings.
Testing standard
CAN/ULC-S102 is the referenced test standard. Materials must have tested values — manufacturer claims without test data are not sufficient.
Work through it in this order
- Identify the building locations where interior finishes will be applied: exits, corridors, rooms, and other spaces.
- Look up the maximum flame spread rating and smoke developed classification for each location under the applicable code.
- Verify that the proposed finish materials have tested values that meet or exceed the requirements.
- Check whether sprinkler status or building height modifies the finish requirements for any location.
Common questions
What flame spread rating is allowed in an exit stairwell?
Exit stairwells have the most restrictive flame spread limits. The maximum value depends on the code edition. Verify the specific provision and confirm the material has been tested to CAN/ULC-S102.
Do sprinklers allow higher flame spread ratings?
In some locations and code editions, sprinkler protection allows higher flame spread ratings for interior finishes. The allowance is location-specific — verify the applicable provision.
How do I get the flame spread rating for a material?
The flame spread rating must come from testing to CAN/ULC-S102. Manufacturers of finish materials should provide tested values. Do not assume a rating based on the material type.