Canadian building code question

What are the building code requirements for stairway headroom in Canada?

The building code sets minimum headroom clearance measured vertically from the stair nosing line to any overhead obstruction. Requirements vary between Part 3 and Part 9 buildings, and reduced headroom is one of the most common code violations in basement renovations.

Stairway headroom is measured vertically from the nosing line of treads and the surface of landings to the nearest overhead obstruction. The code sets a minimum clearance that must be maintained along the full length of the stair and over landings. This requirement is straightforward in new construction but becomes a major design constraint in basement renovations, attic conversions, and buildings with low floor-to-floor heights.

What to check first

• Minimum headroom must be maintained from the stair nosing line to any overhead obstruction.
• The measurement applies along the full length of the stair and over landings.
• Reduced headroom is one of the most common code violations in basement and attic stair designs.

Jurisdiction notes

Work through it in this order

1. Measure the vertical clearance from the stair nosing line to the nearest overhead obstruction.
2. Check the applicable minimum headroom requirement for the building type (Part 3 or Part 9).
3. Verify headroom clearance at all points along the stair including where structure, ductwork, or ceilings may reduce clearance.
4. If headroom is insufficient, evaluate options including lowering the floor, raising the ceiling, or modifying the stair geometry.

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