Correct, it’s offering redundancy. However the probability of corridors serving 10-20 homes per floor being blocked in a large two stair building is way higher than the probability of the single exit stair being blocked in a small building with 20 homes total (max 4 per storey). Hence much safer.
Single-stair gets the New York Times treatment. @holz-bau.bsky.social reminds us why they call the last line the kicker: www.nytimes.com/2026/03/04/b... (gift link)
But none of them at 4-6 storeys are sprinklered. Wood (behind 1-hr gypsum) +sprinklers is safer for egress than concrete/masonry without sprinklers.
In the second issue of EXPO, I look at the history of the condominium in Canada. Why did condos become the primary mode of delivering multi-unit urban housing? Why did we build so many? And what happens now that nobody's buying?
'Fully embracing the single-stair model would improve life in Toronto & beyond by enabling the design of buildings w/ abundant natural light, cross-ventilation, & more generous layouts, and by also supporting the formation of stronger, intergenerational social bonds'
www.kpmb.com/insight/how-...
Vancouver stair width is not increased, Vancouver Building By-Law is 1100mm. The city has it’s own code. Only the British Columbia provincial code is 1500mm, though there is no technical basis to support the width given the extremely low occupant load.
Just went through this for some freelance writing for an American-owned Canadian magazine and was hell to figure out which boxes to tick on that form
Doug Ford said it had to close because the roof was unstable.
Massive snow dump, roof just fine.
Doug Ford lies.
A good graphic to explain all is in the LGA Mid-Rise Manual report
OBC 3.2.2.51 - 6 storeys
Interesting floor plan that shows what mitigations are possible that are not a second stair or sprinklers (neither of which are common in new apartment buildings in France). The lower floors have a short double-loaded corridor with five units of up to 4BR, which I... divisare.com/projects/548...
It is.
Updated to include changes in City of Vancouver, recent change from 16 to 20 storeys in Sweden, and permissions for existing buildings in Nova Scotia.
secondegress.ca/Jurisdictions
For context, the $150,000 is is in reference to high buildings (at 25 storeys, this would be $6,000 per storey annually, or $500 monthly), at 200 sq.ft per storey in floor area savings, this is $2 net rent (back in 2008). Adjust for today’s rents and applicable building height to do today’s math.
"In a residential building, the use of a single staircase results in increased revenues of app. $ 150,000 per year. However, single means of escape requires additional fire protection and a cost-benefit analysis could show which fire safety design solutions that has the lowest life cycle cost."
"Most building codes require two separate means of escape. This is not a preferable option for the property owner, who finances the construction work. Minimising non-rentable space is of great importance and therefore it is very attractive to have as few stairwells as possible."
Fascinating 2008 paper on "Redefining fire safety in Swedish high-rise buildings" speaks to risk-informed design of single exit stair high-rise buildings in Sweden, featuring the Turning Torso (54 storeys, residential/offices) and the Kista Science Tower (31 storeys, offices)
wuz.se/wp-content/p...
Rad Building
A new bombshell modeling report by the State of Minnesota has found that small single-stair buildings with smoke-separated stairwells are likely to be SIGNIFICANTLY SAFER than typical double-loaded apartment buildings
The national code requires a 9.0m distance between doorways, but the prescriptive code also allows the floor areas to be divided by a fire separation and then the 9.0m isn’t required. Not an alternative solution, but an alternative in the sense that hardly anyone is aware it is available in the code
Incorrect. Scissor stairs are permitted by prescriptive code language across Canada, except only that Vancouver did not permit scissor stairs in wood-frame construction until this amendment, and Ontario did not permit combustible construction of exit enclosures till 2023.
Vancouver city councilor, Sarah Kirby Yung said, “Why can’t we have interesting buildings on smaller lots? Once you see it, You can’t unsee it.”
This change will also facilitate the advancement of housing projects such as the "AIR studio pilot project" as there is now an established set of performance requirements to which alternative solution proposals for single exit stair designs can be compared and evaluated.
singlestair.ca/AIR-studio
“During a fire or emergency, stairwells are the critical lifelines for residents and first responders,” said Karen Fry, Vancouver Fire Chief. “The two new stair design options maintain a good level of protection needed to keep those pathways safe while supporting new housing options for Vancouver.”
“Vancouverites deserve buildings and neighbourhoods that are both safe and full of possibility,” said Mayor Ken Sim. “Modernizing our building rules is about making practical, forward-thinking changes that protect people and support more housing options.”
A big thank you to the architects, planners, engineers, builders, emergency responders and other stakeholders engaged in the consultation process to develop the changes. The result is very reasonable and efficient solutions to maintain safety while unlocking "missing middle" housing on small sites.
Today, the City of Vancouver approved the code change to the Vancouver Building By-Law (VBBL) to allow Single Exterior Exit Stair (SEES?!?) for up to 6 storeys in height, as well as accommodating scissor stair layouts for 6 storeys of limited area by reducing the minimum distance between exits.
Excited to share a new video I produced with Urbanarium on their Decoding Timber Towers competition, which challenged teams to design 8–20+ storey buildings out of wood!
Check it out here: www.youtube.com/watch?v=gQ42...
