BC exploring requiring just one staircase for 8-storey residential buildings

BC exploring requiring just one staircase for residential buildings up to 8 storeys

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Could the new architectural design flexibility of more efficient, smaller multi-family residential buildings help address the housing affordability and supply crisis?

More specifically, could multi-family buildings up to eight storeys tall be built with just one emergency exit stairwell? Currently, under British Columbia’s building and fire codes, at least two stairwells are needed for multi-family buildings three storeys and higher.

The provincial government first announced last month it will examine the feasibility with safety and design efficiency as the top considerations, and it formally launched the process yesterday to seek consultants with professional expertise in building design, engineering, and life safety to better understand the potential for single-egress stair (SES) designs.

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“We’re leaving no stone unturned in our work to deliver more homes faster for people,” said Ravi Kahlon, BC Minister of Housing, in a statement. “This work will focus on developing an understanding of if and how this innovation can be incorporated into building and fire codes in a way that maintains and enhances safety, supports access and egress, while providing more homes for people in BC.”

Amongst building development and urban planning circles, the general idea is that such new SES allowances will make it more financially feasible to build housing on small lots, including infill lots, as it can reduce the floor plate size that would otherwise be needed for multiple stairwells, and enables larger apartment units with more bedrooms.

SES designs would also reduce the amount of internal common space, specifically long hallways that add to both construction and maintenance costs.

A theoretical design concept shared by the provincial government for a SES design on a small lot suggests such buildings with a single stairwell could be regulated to have no more than four units per floor.

Such a design means building floors could be efficiently configured around a central atrium stairwell, with the units optimized with more exterior frontage to natural light and air. At least one elevator would still be provided.

Current two exit stairwell requirement - 1

A potential single-egress stair concept (left) and the current two exit stairwell requirement (right). (LGA Architectural Partners)

Advocates suggest many non-profit housing organizations already own or can only afford to buy smaller lots. If SES designs were enabled for such low-rise building designs, the organizations could build on their small lot, and potentially not have to form a costly land assembly by acquiring adjacent lots. This could also help lower rents.

“Nobody loves long, dark hallways or windowless bedrooms, but that’s often the way we’re forced to build apartments in BC,” said Bryn Davidson, the co-owner of Lanefab Design/Build & Oori Architecture.

“In most of the rest of the world, apartments can have more daylight, better cross breezes and more greenspace, and they don’t need to take up a whole block. What’s missing in BC is a small change to the building code to allow single stair buildings. I hope we can unlock this important design tool.”

According to Uytae Lee, who is best known for his About Here YouTube channel, and was recently appointed to the board of BC Housing, two exit stairwells were first introduced to the building code in 1941, at a time when fire safety considerations were at the absolute forefront. However, he says, major advances have been made since then in the fire safety designs of new buildings, and “it’s appropriate to assess whether that rule is still relevant now.”

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New building designs with SES are currently permitted in New York, Seattle, and many European cities.

In Seattle, since the 1970s, the building code allows residential buildings up to six storeys with no more than four units per floor to be served by a single stairwell. Germany also permits SES for office and residential buildings up to 72 ft or roughly seven storeys.

However, the government of the United Kingdom recently took a major step back from SES designs, as part of the continuation of its sweeping building safety reforms following the 2017 Grenfell tower fire that killed 72 people. The cause of the devastating fire at the 1974-built, 24-storey tower was deemed to be started by an electrical fault in a refrigerator on the fourth floor, which then rapidly spread to upper floors due to the building exterior’s flammable materials.

In July 2023, the UK government stipulated a second staircase will be required in all new buildings taller than 18 metres (59 ft) or roughly equivalent to more than six storeys for residential uses. Initially in early 2023, the proposed threshold requiring a second staircase was originally set at 30 metres (98 ft) or roughly 10 storeys for residential uses, but this threshold was later lowered to 18 metres following consultation.

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