A builder standing on a narrow parcel in the Richmond can picture a compact apartment house that would be unremarkable in Montreal or Berlin. In San Francisco the same sketch often dies in the code. The latest version of that argument centers on single-stair housing, a layout that relies on one enclosed stair rather than two and that supporters believe can fit more livable homes onto small urban lots. Mayor Daniel Lurie has advanced a local change meant to make that layout easier. Housing advocates who pushed for the reform now say the version on the table is so limited that it will not produce many new buildings at all.
What City Hall actually changed
Lurie campaigned on a promise to make it easier to build homes, and the stair rule sits inside a larger package of code and process tweaks. The reform does not throw out the two stair standard for most of the city. It creates a narrower path for certain buildings, with height limits, occupancy limits, and extra fire protections still attached. In practice, that means a project must still satisfy the fire department, the building department, and neighborhood review before a single stair plan has any chance of approval.
Advocates had asked for something closer to rules already used in Seattle and in much of Europe, where a well protected stair can serve a mid rise building if travel distances are short and sprinklers, alarms, and resistant doors are in place. The San Francisco version, as critics have described it, keeps so many conditions that only a thin slice of lots could qualify. A reform can be real on paper and still be rare in the built city.
Why advocates say the reform changes little
The complaint is not that Lurie ignored housing. It is that the stair change was sold as a way to unlock small apartment buildings and then drafted so tightly that few projects can use it. A meaningful allowance would let a four or five story building on a standard lot use one stair, with sprinklers and short corridors, and still meet modern fire rules. Critics argue the city kept the exception so small, and the review so heavy, that architects will keep drawing two stairs or will not draw the building at all.
That is why the phrase single-stair housing now carries a political edge in San Francisco. Supporters still like the idea. They do not like a version that preserves the old outcome under a new name. If the only buildings that qualify are unusual sites with unusually patient owners, the reform will not show up in rent data, permit data, or the streetscape.
How other cities already do this
Seattle has allowed certain one stair residential buildings for years, within height caps and with strict construction standards. Montreal, Berlin, and many other cities treat a single protected stair as ordinary for mid rise apartments. The logic is simple. Two stairs consume a large share of a small floor plate. On a lot that is only 25 or 30 feet wide, the second stair can erase the space that would have been a bedroom or a second bathroom.
Housing researchers who study these point access buildings argue that the design produces more family sized units and fewer long hotel style corridors. I have walked buildings like that in other cities, and the apartments feel like houses stacked in a line rather than like dorm rooms off a hallway. San Francisco does not have to copy any one foreign code. It does have to decide whether its fear of the layout is still matched by the evidence from places that have lived with it.
Fire safety is the hard objection
Fire officials do not oppose more housing in the abstract. They oppose a design they believe leaves residents with one way out if smoke fills a stair. That fear is serious, and it deserves a direct answer rather than a slogan about red tape. Modern one stair buildings are not bare wooden flights open to the hall. They are enclosed, pressurized or vented in specified ways, paired with sprinklers, alarms, and limits on how far a resident must travel to reach the stair.
The debate in San Francisco is really about whether those layers of protection are enough. Critics of the mayor’s modest change say the city invoked fire safety to justify a rule so cautious that it fails as housing policy, without settling the safety question in a way builders can use. A clearer standard, written with the fire department rather than around it, would tell an architect exactly which heights, which materials, and which exiting distances are acceptable. Ambiguity is not the same thing as caution.
The economics of a narrow lot
Land in San Francisco is expensive, and construction is expensive, so a building has to use its square footage well or it does not get built. Two stairs, two exit paths, and the walls around them can consume a startling share of a small floor. Add elevators, trash rooms, and bike storage, and a theoretical six unit building becomes a four unit building with awkward room sizes. That is the gap single-stair housing is supposed to close.
If the reform only applies to a rare combination of lot width, height, and occupancy, the gap stays open. Developers who build larger projects on merged lots already have room for two stairs. The projects that need the exception are the small ones, often on lots that cannot be merged, in neighborhoods where residents say they want homes but resist bulk. A rule that helps only large sites helps the projects that were already closest to penciling out.
What builders still cannot count on
Architects describe a familiar loop. A client asks whether a one stair plan is legal. The architect says it depends. The fire department may want additional features. Planning may want a smaller building. The structural costs of a concrete or heavy timber stair shaft may erase the space savings. Months pass. The client sells the lot or builds a single family house instead.
Lurie can fairly say that no single code edit will end that loop. Critics answer that a code edit which does not change the loop is not a housing reform. They want a path with predictable yes or no answers, published early, so a builder can price the project before hiring a team of consultants. Without that, single-stair housing remains a conference topic rather than a permit category.
Even a sympathetic planner will admit that uncertainty is a cost. Every extra meeting is a month of interest on a loan, and small builders feel that cost first. If the city wants this reform to matter, it has to publish examples of projects that would pass, not only a list of conditions that might.
Politics of a small concession
Housing policy in San Francisco is a negotiation among people who agree the city needs homes and people who fear what new homes will do to streets, shadows, and fire response. A mayor who wants a win will often take the version that can pass. A tight exception lets City Hall claim progress while reassuring skeptics that towers of one stair buildings are not about to appear on every block.
There is a cost to that kind of win. Advocates who spent years explaining the design feel the city took the language and left the substance. Neighborhood groups who opposed any change may still feel the door has been opened. Both sides can leave unsatisfied, and the public sees another announcement that does not alter the skyline. Trust erodes when reforms are named for the problem they do not quite solve.
Lurie still has time to widen the allowance if early permits show almost no one can use it. A mayor is judged on results, and housing results arrive slowly enough that a weak first draft can be repaired. The risk is that staff treat the current text as finished and move on to the next announcement.
What a real test would require
A fair test would pick a clear height, a clear maximum number of units per floor, and a clear set of fire protections, then allow that package on ordinary lots for a set number of years. The city could track permits, construction costs, and any fire incidents, and publish the results. If the package proves unsafe or unused, it can be tightened. If it produces homes, it can be widened. That is ordinary governance, not a gamble.
Until then, the argument over single-stair housing will keep circling the same block. Lurie has shown he is willing to touch a rule that previous administrations left alone. Touching a rule is not the same thing as changing what gets built. The measure of this reform will not be the press release. It will be whether a family sized apartment rises on a lot that, under the old code, could only hold a staircase and a compromise.