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Policy & Zoning | Single-Stair Reform

Single-Stair Reform: Why Sixplex Now Pencils

The BC Building Code's 2024 single-egress amendment was technical, narrow, and barely covered in the housing press. It also rebuilt the economics of the small multiplex more than any zoning change.

Key Takeaways

  • ✓BC permits single-egress stairs in residential buildings up to six storeys, with strict life-safety conditions.
  • ✓The change took effect with the 2024 BC Building Code update.
  • ✓A second stair plus corridor consumed 20–25% of each small-lot floor plate before the reform.
  • ✓The reform is what makes sixplex viable on standard 33-foot lots.

Before and After

Before (2023 BC Building Code)

Any residential building over three storeys or with more than four units required two means of egress — typically two stairs separated by a fire-rated corridor. On a 33-foot lot, two stairs ate roughly 25% of every floor plate.

After (2024 amendment)

Buildings up to six storeys, with strict fire and life-safety conditions, can be served by a single egress stair. The corridor goes away. The floor plate becomes usable. Sixplex and small mid-rise typologies become buildable on standard urban lots.

The Conditions That Apply

The amendment is not an open door. The single-egress option carries specific conditions, all designed to maintain fire and life-safety equivalency to the two-stair baseline. Builders relying on the provision must satisfy every condition; missing one forces the project back to two stairs.

  • Maximum six storeys above grade.
  • Maximum building area and unit count thresholds set in the amendment.
  • Sprinkler protection throughout (NFPA 13 standard).
  • Pressurized stair shaft or other smoke control measure.
  • Maximum travel distance from any unit to the stair.
  • Limit on dwelling units per storey served by the single stair.

The exact threshold values sit in Division B of the 2024 BC Building Code. Confirm the current numbers with the Building and Safety Standards Branch before relying on them in design.

The Floor-Plate Math

Take a standard 33-foot Vancouver lot at 4,000 sq ft. Vancouver R1-1 at 1.0 FSR (secured-rental track) gives 4,000 sq ft of building. A two-stair scheme with rated corridor consumes about 200 sq ft per floor of vertical-circulation overhead. A single-stair scheme drops that to about 80 sq ft per floor. Across four storeys, the saving is roughly 480 sq ft — the difference between a four-unit and a six-unit project at the same gross floor area.

The reform does not by itself add any new buildable area. It changes how the existing FSR is divided between circulation and units. That is enough to flip a sixplex from non-viable to viable.

What This Means for Design

A single-stair sixplex floor plate looks more like a small European apartment building than a BC condo: a central stair, two units per floor, units extending the full width of the building. Daylight reaches every unit because there is no double-loaded corridor blocking through-ventilation.

The design change is consequential. Design quality concerns about early-wave Bill 44 multiplexes have less to do with the typology and more with the constrained floor plates that two-stair requirements forced.

Best For

  • ✓ Sixplex feasibility on standard 33-foot urban lots near transit.
  • ✓ Architects designing for daylight and cross-ventilation in small multiplex.
  • ✓ Builders comparing four-unit and six-unit pro formas under the same FSR cap.

Usually Fails When

  • ✕ You exceed the maximum unit-per-storey or building-area thresholds in the amendment.
  • ✕ You skip the sprinkler or pressurized-shaft conditions.
  • ✕ You assume the provincial code allowance applies without checking municipal supplemental requirements.

What To Verify Before Spending Money

  • → The current BC Building Code thresholds with the Building and Safety Standards Branch — values can change between code editions.
  • → Whether your fire-protection consultant has signed off on the equivalent-safety analysis.
  • → Whether your municipality has any local rule that goes beyond the provincial code.

Frequently Asked Questions

When did BC allow single-stair buildings up to six storeys?+
The Province announced single-egress provisions for residential buildings up to six storeys in early 2024 as part of an amendment to Division B of the BC Building Code. The change was framed as part of the Housing Action Plan and was timed to take effect alongside Bill 44 implementation.
Is BC the first jurisdiction to do this?+
No. Single-stair residential buildings are common in Europe, Asia, and parts of the United States (notably Seattle and New York City). Until the 2024 amendment, most of Canada and the rest of North America required two egress stairs above three storeys. Quebec and Ontario have not adopted similar provisions as of mid-2026.
Does single-stair compromise life safety?+
The fire-protection conditions attached to the BC provisions — sprinklers, pressurized shafts, travel distance limits, unit count caps — are designed to deliver equivalent or better fire performance to the two-stair baseline. The detailed analysis is in the amendment justification published by the Building and Safety Standards Branch.
Why does single-stair matter for SSMUH sixplexes?+
A sixplex on a 33-foot Vancouver lot at 0.7 FSR has roughly 2,800 sq ft of building. Two stairs plus their corridor consume 600–800 sq ft of that across three or four storeys. A single stair frees that area for living space, making six small units of 350–450 sq ft viable instead of four 600 sq ft units.
Does the change apply to wood-frame construction?+
Yes, within the BC Building Code combustible-construction limits. Six-storey wood-frame residential has been allowed in BC since 2009; the single-stair amendment builds on that envelope without changing the structural rules.
Is the amendment retroactive?+
No. Buildings permitted before the amendment continue under the code in effect at permit issuance. The new provisions apply to new permit applications.

Official Sources Referenced

Province of BC: 2024 BC Building Code amendments and bulletins
https://www2.gov.bc.ca/gov/content/industry/construction-industry/building-codes-standards/the-codes/2024-bc-codes
Building and Safety Standards Branch: Code change announcements
https://www2.gov.bc.ca/gov/content/industry/construction-industry/building-codes-standards
Province of BC: Housing Action Plan (single-egress context)
https://www2.gov.bc.ca/gov/content/housing-tenancy/local-governments-and-housing/housing-initiatives
Canadian Wood Council: Single-Stair Buildings in BC (technical brief)
https://cwc.ca/
NFPA 13: Standard for the Installation of Sprinkler Systems
https://www.nfpa.org/codes-and-standards/all-codes-and-standards/list-of-codes-and-standards/detail?code=13

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