Canadian building code question

What are the building code requirements for exit stairwell pressurization in Canada?

The NBC requires stairwell pressurization in buildings where the highest floor level used by occupants is more than 18 m above grade, as part of the smoke control measures for high-rise buildings.

Stairwell pressurization keeps smoke out of exit stairs during a fire, allowing occupants to evacuate and firefighters to access upper floors. The National Building Code triggers this requirement based on building height and ties it to the broader smoke control and fire safety system design for high-rise buildings.

What to check first

  • Stairwell pressurization is required in buildings where the highest floor used by occupants is more than 18 m above grade.
  • The pressurization system must maintain a minimum pressure differential to prevent smoke from entering the stair shaft.
  • Design must account for door openings, stack effect, wind pressure, and HVAC interaction.

Jurisdiction notes

National baseline

NBC Part 3 Division B Subsection 3.2.6 covers smoke control requirements including stairwell pressurization for high-rise buildings. CAN/ULC-S1001 provides referenced testing standards.

Provincial variations

Some provinces have different height thresholds or additional smoke control requirements. Ontario and BC may have specific amendments to the high-rise definition or pressurization standards.

Project-specific variables

Building height, number of exit stairs, HVAC system design, building tightness, and climate zone all affect the pressurization system design.

Work through it in this order

  1. Determine if the building meets the high-rise threshold requiring stairwell pressurization.
  2. Review the NBC smoke control requirements applicable to the building's occupancy and height.
  3. Verify the design pressure differential and airflow requirements for the stairwell pressurization system.
  4. Confirm interaction with other building systems including HVAC, fire alarm, and emergency power.
  5. Check provincial amendments and referenced standards for additional design requirements.

Common questions

At what building height is stairwell pressurization required?

Under the NBC, stairwell pressurization is required when the highest floor level used by occupants is more than 18 m above grade, which is the high-rise building threshold.

What pressure differential is required for stairwell pressurization?

The NBC and referenced standards specify minimum pressure differentials that must be maintained between the stairwell and adjacent spaces, typically accounting for door opening scenarios.

Does stairwell pressurization require emergency power?

Yes. Stairwell pressurization fans must be connected to emergency power to operate during a fire when normal power may be interrupted.