The building design that could crack the code on climate adaptation

In most of Canada, low- and mid-rise apartment buildings are designed like hotels and dormitories: long hallways with units on either side, capped off with staircases at the ends. Once you see it, it’s everywhere; the design forces buildings into the particular shape and dimensions that now fill Canadian cities, and for those living in them, there are consequences, too.

Because the hallway has to connect every unit to two staircases, the typical building design can’t allow for cross breezes, and units with more space are rare.

The layout is baked into provincial housing codes, which require two staircases for fire safety, typically two floors and up. But architects and urban planners stress that buildings can be fire safe with just one staircase: a change that would allow more density and livability, while bringing a host of climate-related benefits. The province of British Columbia is currently exploring the possibility of updating its building code to make them legal.

Most of the world builds multi-family housing with what are called “point access blocks,” explains Michael Eliason, founder of Seattle-based architecture think tank Larch Labs. Instead of building apartments around two staircases (which is the norm in Canada and the United States), compact buildings are constructed with just one staircase. He points to walk-up buildings, rife with character and community, in places like Berlin, Mexico City and Tokyo.

“The way we build housing in the U.S. and in Canada as well, where we typically have at least two stairs, a corridor separating them, and then units on either side...is a little bit of an anomaly,” he explained.

Ditch the second staircase, and receive a host of benefits, explained Eliason, who was commissioned to produce a report on the buildings for the City of Vancouver in 2021. You can build more housing on smaller lots, and the units typically have more light and can accommodate more bedrooms with less square footage. Instead of apartment buildings mostly made up of studios and one-bedrooms, in point access blocks it’s more typical to have three-bedroom units that can accommodate families and other living arrangements.

Cross breezes and embodied carbon

The skinnier single-stair buildings also contribute to climate action and adaptation, Eliason has learned through his work in North America and Germany. He’s especially interested in the intersection of climate and urban planning, and is writing a book on “low-carbon ecodistricts” that also address housing shortages.

Instead of large buildings with apartments that are blocked off from air flow, the layout of point access blocks allow for cross breezes, which are typically reserved for houses.

Cross breezes are an important way for people to stay cool at home as heat waves intensify due to climate change. During the heat dome in 2021, more than 600 people in B.C. died due to extreme heat. New Westminster experienced disproportionate deaths due to extreme heat. Those who died mostly lived in older apartment buildings: in particular, three and four-storey walk-ups with no cross-breeze and no cooling unit.

Another benefit related to climate is that single-stair buildings have less embodied carbon emissions (which are the emissions associated with building materials). He explains that there is a lot of wasted space in typical larger units, which are filled with walk-in closets and other “things you don’t need” because they’re unnecessarily large to fit the dimensions offered by the building plan.

“You have a smaller footprint for an equivalent number of bedrooms...less floor area means less cost, especially if the cost of the two building types is somewhat comparable. It's significantly less embodied carbon,” he explained, stressing that the units should also be more affordable.

“There's less surface area, there's less floor area. All of these things start adding to the embodied carbon of the building.”

Even the pipes make a difference, he said, noting that there is a reduction in the length and number of pipes needed, which also leads to less embodied carbon. About 11 per cent of global emissions come from the embodied sector, which includes the production of building materials such as cement, along with the construction process.

Changing building codes

If B.C. decided to update its building code, it could be following in the footsteps of other North American cities that have pushed back against the double staircase standard. In Seattle, for example, single-stairway buildings are allowed for buildings up to six storeys.

B.C.’s Ministry of Housing says it’s currently “exploring options to enable” one staircase buildings, and it expects to share more information soon.

“We’ve seen research from around the world that has shown single-stair residential buildings can be designed with more opportunities for natural cross-ventilation in apartments,” said Minister of Housing Ravi Kahlon.

“We know the building code needs to evolve to allow for designs that are more climate-friendly and employ passive cooling, and we’re looking to other jurisdictions around the world on how to make that happen here in British Columbia.”

Meanwhile, there is also a push for Canada’s National Building code to allow for single staircase buildings. Architect Conrad Speckert, who developed his graduate thesis at McGill University on point access blocks across the world, submitted a code change request at the national level, which will be prioritized in the next cycle of building code priorities between 2025 and 2030. His thesis found that Canada is the second most restrictive country in the world when it comes to constructing single-staircase buildings, only behind Uganda.

Specifically, he asked the government to update its code to allow for “single exit multi-unit residential buildings of up to six storeys, requiring additional life safety measures and placing limits on the occupant load and number of dwelling units per storey served by the single exit.” Translated, that means allowing for buildings with a single stairway, where instead of two main fire exits there are additional fire suppression systems and limits on the number of people who will need to evacuate all at once.

If it’s nationally accepted, provinces will still need to adopt the code, noted Speckert. However, a handful of chartered cities in Canada – Saint John, Winnipeg, Vancouver, Lloydminster, and Montreal – have the power to municipally implement bylaws that would allow for single staircase buildings.

It’s because of that power that Montreal has more “missing middle” housing than other major cities in Canada: multiplexes, townhouses, and apartment buildings less than five storeys.

“What Montreal does is they have two very efficiently dimensioned stairs, and you're basically allowed to make them spiral stairs, which, in the national code you're not allowed to have a spiral staircase serve as an exit,” Speckert explained.

However, since it’s a municipal bylaw, “if you're an architect in Montreal, you can use a spiral staircase as an exit for a small building. But if you're in Laval or Brassard, you can't.”

To Speckert, it’s a timely moment for the national building code to take leadership on single staircase buildings in hopes that provinces will adopt the measure. The first building codes were written in the 1940s, and largely based on what American cities such as Chicago were doing at the time: not to prevent fires, but to allow people to escape when fires often occured in timber frame buildings.

Now, fire safety requirements are much different, explained Speckert. Newer buildings have fire alarm systems, fire-rated walls, sprinkler systems, and more.

“These requirements — that come from a time 100 years ago, where the risk level was different — sometimes aren't appropriate today,” Speckert said. “I'm the first person to say that surely larger buildings should have two exit stairs. But, on small, constrained sites, there's a better way to achieve an acceptable level of safety.”

Ultimately, single stair buildings make sense in the present day, which is much different than the time when Canada was first designing its building codes, Eliason agrees: now, Canada doesn't just need more housing, but homes that consider density, affordability, livability, and climate change.