Typology
3-Storey Apartment Building

Occupancy
Group C, 10 Dwelling Units

Classification
2023 National Building Code Alberta Edition, Part 9

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Status: Submitted for Building Permit, City of Edmonton (February 2025)

An alternative solution has been submitted for this three-storey small apartment building on a typical lot (33’ x 150’) in downtown Edmonton. The site is zoned for medium-scale residential use and allows for buildings up to 16 metres in height with side yard setbacks from the adjacent homes built in the early 20th century. The proposed building contains 10 dwelling units, with a total of six dwelling units on the second and third floor served by the single exit stair.

Prescriptive building code compliance requires two means of egress for buildings over two storeys in height. Following a number of test fit scenarios, providing two separate exit stairs limits the project to a maximum of 6 dwelling units. As a result of the single exit stair alternative solution, the site accomodates an extra 4 dwelling units to improve the feasibility of the project and increase housing supply.

This solution enables the creation of more affordable "missing middle" housing types that are well-suited for smaller infill lots in mature neighborhoods within Edmonton's downtown core without the need for land assembly of multiple adjacent properties.

The proposed building design includes three dwelling units on each of the upper floors served by a public corridor, such that prescriptive compliance with NBC/AE 9.9.9.2.(1) requires access to a minimum of two exits from public corridors serving each storey. An alternative solution is proposed for the building to be served by a single exit stair. The dwelling units on the upper storeys are proposed to be served by a public corridor with access to a single enclosed exit stair. The travel distance in this corridor is less than the 6m maximum travel distance permitted for dead-end corridors.

The proposed alternative solution incorporates a combination of active and passive fire protection measures designed to ensure safe and timely egress during emergencies. These measures are based on a review of established standards including the NFPA 101 Life Safety Code requirements for single exit stair apartment buildings of up to 4 storeys in height. Key compensatory measures include:

• Sprinkler System: A sprinkler system designed to the NFPA 13-R standard provides effective fire suppression, mitigating fire growth and improving occupant safety.

• Enhanced Compartmentation: The fire-resistance rating of load-bearing assemblies, exit enclosure and dwelling unit fire separations and the fire-protection rating of doors are upgraded.

• Flame Spread Limitation: Interior finishes in the exit and public corridors are limited to a flame spread rating of 25 or less (per CAN/ULC S102 testing), minimizing fire propagation in the egress route.

• Minimized Travel Distances: Travel distances to the single exit are very short, ensuring significantly reduced egress time compared to travel distances permitted for two exit conditions.

• Occupant Load Management: The number of suites per floor are limited to maintain a low occupant load, to facilitate timely egress and avoid counterflow with emergency responder ingress.

• Fire Safety Plan: A comprehensive fire safety plan will be implemented, detailing emergency evacuation procedures and maintenance protocols for life safety systems.

These alternative solution measures ensure the proposed building design meets the objectives of the building code and achieves at least the same level of performance and level of acceptable risk as the applicable acceptable solutions in Division B of the NBC/AE.