Canadian building code question

What are the building code requirements for interconnected floor spaces in Canada?

Interconnected floor spaces — including atriums, open stairs between floors, and multi-storey lobbies — are governed by specific provisions that address fire separation, smoke control, sprinkler requirements, and egress. The applicable requirements depend on the number of interconnected storeys, occupancy, building height, and how the province has adopted the relevant code provisions.

Interconnected floor spaces are among the most complex conditions in the building code because they create exceptions to the normal floor-by-floor fire separation model. When floors are intentionally connected through atriums, open stairs, or multi-storey voids, the fire safety strategy must account for smoke spread, egress paths, and sprinkler coverage across multiple levels. The safest approach is to identify the exact type of interconnection before applying any code provisions.

What to check first

  • The code treats interconnected floor spaces differently from standard floor-by-floor fire compartments, and the requirements change with the number of interconnected storeys.
  • Smoke control, sprinkler coverage, and fire separation provisions all interact in interconnected floor conditions and must be checked together.
  • Provincial adoption and AHJ interpretation can significantly affect how interconnected floor space provisions are applied on a specific project.

Jurisdiction notes

National baseline

Start with the NBC provisions governing interconnected floor spaces, atriums, and the conditions under which normal floor separations can be modified or omitted.

Province and edition check

Confirm how the province adopts the interconnected floor space provisions and whether any amendments change the storey limits or fire safety requirements.

Design-specific variables

The number of interconnected storeys, whether the space qualifies as an atrium, sprinkler status, and occupancy classification can all change the applicable code path.

Work through it in this order

  1. Identify the type of floor interconnection: atrium, open stair, escalator void, multi-storey lobby, or another condition.
  2. Determine the number of interconnected storeys and confirm how the code classifies the space.
  3. Review the NBC provisions governing fire separation modifications, smoke control, sprinklers, and egress for the applicable interconnected condition.
  4. Verify provincial adoption and document the cited provisions, including any AHJ-specific interpretations, before advancing the design.

Common questions

How many storeys can be interconnected before additional requirements apply?

The threshold depends on the adopted code edition and provincial adoption. The code typically distinguishes between two-storey and larger interconnections, with more stringent requirements as more floors are connected.

Is an open stair between two floors always considered an interconnected floor space?

Not necessarily. The code has specific definitions for what qualifies as an interconnected floor space versus other types of floor openings. The classification determines which provisions apply.

Do interconnected floor spaces always require smoke control?

In many cases, yes, but the type and extent of smoke control depends on the number of interconnected storeys, building height, occupancy, and provincial adoption.