Inge Roecker stands in the kitchen of her apartment in the Vancouver building she designed.Jennifer Gauthier/The Globe and Mail
When it’s done, the building will barely register as new. The three-storey apartment complex will settle onto a leafy street as if it had always been there – faced in brick, its twin balconies nudging toward the sidewalk.
But inside, this project in an older Toronto neighbourhood will express radical ambition. Its design unmakes more than half a century of North American assumptions about fire safety, architecture and how to build cities. Designed by Toronto’s Office Ou, the six-unit building will only have a single staircase, not two as Canadian building codes usually require.
That change – for which local building officials gave special approval – has consequences. It will produce unusually comfortable apartments, each with windows on two or more sides, and a shared stairway where neighbours can encounter one another.
Such “single exit stairway” or “single egress” buildings are common outside North America. Now, several Canadian jurisdictions are re-examining their rules to allow such developments, including the City of Vancouver, which altered its building code last month.
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In Canada and the United States, most buildings taller than two storeys must have a second stairwell or exterior fire escapes. A typical apartment building features a long, space-consuming corridor that cuts through its middle, with apartments on each side and access to stairwells at either end. North Americans take this form for granted, but it is not the only way to build multiunit residential buildings.
A few designers laid the groundwork with variations on the theme. In 2011, Vancouver architect Inge Roecker, an associate professor in the University of British Columbia’s School of Architecture and Landscape Architecture, developed an eight-storey building in Chinatown. The 26-unit building, where she now lives, has two intertwined staircases, a technique known as “scissor stairs.” Both open up onto an outdoor passage, and each apartment has windows onto this passage, as well as on the building’s opposite side, allowing light and breezes to flow through, just as they would in a house.
None of that was permitted under Vancouver’s building code. Ms. Roecker obtained special permission by adding safety measures, including powerful fans that turn on automatically when the fire alarm is activated and clear smoke out of the stairwells.
Ms. Roecker’s eight-storey, 26-unit apartment building in Vancouver’s Chinatown on Dec. 19.Jennifer Gauthier/The Globe and Mail
Yet other single-stairway designs have recently faced resistance from fire chiefs and building officials who view them as risky. Advocates, on the other hand, say this approach to construction can deliver structures that are safer than the Canadian norm – and provide comfortable family homes, even in small buildings that can slide into existing neighbourhoods.
The owner/developers of the Toronto apartment project, former developer Marvin Green and planner Pamela Blais, say theirs is the first single-stairway project to be approved there in the postwar era. Ontario’s 84-year-old building code forbids this approach; they secured special permission by convincing municipal officials that the design is safer than the prescribed minimum standard.
They were inspired by a growing public conversation about the merits of single exit stairway buildings. “We had discussed [single exit stairway] early on,” Mr. Green said, “and we had heard there’s progress.”
Indeed, Vancouver City Council voted in mid-December to allow single exit stairway apartments – the first jurisdiction in Canada to clearly take such a step. Earlier last year, the City of Edmonton introduced a guide to “alternative solutions” for such buildings, providing a road map for their approval, as has the City of Toronto.
Ms. Roecker is an associate professor in the University of British Columbia’s School of Architecture and Landscape Architecture.Jennifer Gauthier/The Globe and Mail
Meanwhile, officials overseeing Canada’s National Building Code, which sets the pace for provincial versions, are adapting fire codes to allow single exit stairway designs (a.k.a. “point access blocks”).
In the U.S., cities such as Seattle and New York now permit new single exit stairway buildings, as does the state of Hawaii. The design is spreading to other states and has even won support from traditional opponents such as national fire-safety and firefighter organizations.
By contrast, in Australia, Britain, Singapore and much of Europe, single exit stairway buildings are not only commonplace, they can rise up to 20 storeys (typically with elevators as well).
In recent years, proponents have made the case that contemporary fire-safety technologies have rendered obsolete the corridor-plus-two-stairwell layouts that have defined North American multiunit buildings since the 1940s.
New single exit stairway buildings incorporate modern safety systems, such as automatic sprinklers and enhanced fire-retardant building materials, that are not typically used in older and more traditional North American apartment buildings.
According to new research from the Pew Charitable Trust, four- to six-storey single exit stairway buildings equipped with sprinklers have a “strong safety record” versus conventional apartment buildings and single-family homes. They also cost 6 per cent to 13 per cent less to construct, a significant savings.
Proponents also argue that this reform creates other spinoff benefits – including larger and more livable apartment layouts.
Such buildings can also add density to low-rise residential neighbourhoods that are economically out of reach for most families and have been losing population for decades.
“The design of smaller-scale buildings allows for architectural invention, improved density and generates a more interesting city,” the award-winning London architect Paul Karakusevic observes. “It’s a great way to use smaller lots and brings housing diversity.”
“You have family units in this kind of building and you know your neighbours,” Ms. Roecker said, casting the accelerating single exit stairway revolution in clear terms: “This is the missing link to the missing middle.”
Drawings of a proposed new apartment building in Toronto by Office Ou.Supplied
When Mr. Green and Ms. Blais started thinking about erecting a compact apartment building on their lot, they had a conventional structure in mind. But their architects told them the small site made that approach uneconomical: Too much rentable floor space would be lost to corridors and stairs.
The early design “was compromised in many weird ways,” said Sebastian Bartnicki, one of Office Ou’s co-founders.
In late 2024, the couple decided to pivot to a single stairway and hired building code consultant Jack Keays to get a design approved by city officials. The workaround, known as an “alternative solution proposal,” can have “an acceptable level of risk,” Mr. Keays explained. But it needs to outperform what’s set out in the building code.
Mr. Keays and Office Ou proposed four key enhancements: a building-wide sprinkler system; fire-retardant floors, walls and doors made to withstand fire for longer than the thresholds required under the building code; a staircase and landings wide enough for firefighters to pass exiting residents; and a mechanical ventilation system, with a backup generator, that forces pressurized air into the stairwell in the event of a fire and so prevents smoke from filling that space.
Toronto building examiners initially balked at Office Ou’s solutions. “It’s all about negotiation with the city, which was very complicated and convoluted,” said Office Ou co-founder Uros Novakovic.
Frustrated by the lack of progress, Mr. Green and Ms. Blais took to social media to complain about the roadblocks. Their posts came to the attention of one of Mayor Olivia Chow’s staff. “There had to be political involvement,” Ms. Blais said. “The mayor requested that the chief building official resolve the matter.”
“This was the first single exit stair project with an alternative solution proposal that has come to our attention,” Ms. Chow’s spokesperson, Shirven Rezvany, explained. “Our goal was to help find a way to make it work and set an example that this kind of building is feasible.”
The City of Toronto issued a building permit for Office Ou’s proposed new apartment building in November, 2025.Supplied
After months of deadlock, the mayor’s intervention worked, and the city issued a building permit in early November. While the approval document states that the design isn’t a “precedent” – anyone who wants to build a single exit stairway building still needs to develop a specific solution – Mr. Keays points out that such projects can and do lead to changes in building codes.
The most encouraging example: the advent of tall timber construction using engineered wood components. A decade ago, the maximum allowable height for buildings made from wood was three storeys. But a handful of builders set out to take advantage of advances in engineered timber, which has very different structural and safety characteristics than conventional wood-frame construction, to propose four- to six-storey wood buildings.
“Then we went to six,” Mr. Keays recalled. “And everyone’s like, ‘Oh, nothing happened to these six-storey buildings. They were totally fine.’ And next thing we’re allowed 12s, and now we’re allowed 18s.”
He predicts a similar arc for single exit stairway buildings, with first movers such as Mr. Green and Ms. Blais pioneering solutions that other small-scale developers will take up and then tweak to secure permits for more ambitious projects that rise to five or six storeys, as is common outside North America.
“If you go around the world,” Mr. Keays observed, “there’s hundreds of examples. We are far from the leading edge. We are on the trailing edge.”
John Lorinc is special to The Globe and Mail