The Board of Supervisors' own budget analysts studied what it would cost to force fire sprinklers into 126 aging San Francisco high-rises and landed on a range so wide it could vindicate everyone: as little as $15,000 per unit, or as much as $224,900.

For months, both camps in San Francisco's residential sprinkler fight treated a pending report from the Board's Budget and Legislative Analyst as the referee that would finally price out the mandate — homeowners expecting confirmation of ruinous six-figure costs, the building trades expecting those numbers exposed as inflated. It has now landed, and it broke nothing. The analysis concluded the affected buildings are too varied to generalize about at all, and handed the dispute to a technical advisory council that convenes next month — keeping a fight that has already delayed the mandate by five years wide open.

The mandate itself dates to a 2022 update to the city's fire code. It requires fire sprinklers in every living unit of residential high-rises built before the mid-1970s that stand roughly 12 stories or taller and lack a second protected interior stairwell — about 126 buildings holding close to 10,000 residences, clustered in Nob Hill, Telegraph Hill, the Marina, Pacific Heights and Russian Hill. Homeowners who fought the rule warned it could cost $200,000 to $300,000 a unit, bankrupt fixed-income seniors and depress resale values. The San Francisco Building and Construction Trades Council countered that the work could be done for as little as $15,000 to $20,000 a unit — a modest price, in their telling, for saving lives.

Supervisors Stephen Sherrill and Danny Sauter, whose districts contain many of the buildings, asked the Board's Budget and Legislative Analyst to referee. As first reported by the San Francisco Chronicle, the analyst's answer was that there is no single number. Examining three hypothetical 50-unit buildings, the report found retrofit costs could run anywhere from $15,000 to $224,900 per unit. The cheapest cases were buildings with, in the report's words, "relatively favorable existing conditions" — those already partly sprinklered, with "core system components — such as a fire service line, standpipe, and portions of interior piping" already in place. The most expensive were older towers needing new water service, new pumps and concealed piping run through walls and low ceilings.

"When there are this many buildings, there are going to be a lot of edge cases, and buildings that take a lot of work to get water pumped up to the top of a hill," Sherrill told the Chronicle. "We can't have mandates in the name of safety that don't take cost to residents into account."

Predictably, each side read the same range as proof it was right. Ahsha Safaí — a former District 11 supervisor and an original co-sponsor of the 2022 rule, now a spokesman for the Building and Construction Trades Council — argued most buildings still fall at the cheap end and that the mandate can proceed building by building. "We're going to approach each building on an individual basis," Safaí told NBC Bay Area, adding that "there will be some buildings based on hardship, based on infrastructure, based on water that might get an exemption."

For the homeowners, the top of the range was the headline. At "The Heights," a Pacific Heights condominium that already has sprinklers on its exterior fire escapes and in its hallways but still falls short of the new rule, association president Steven Stiller framed it as one costly city order too many. "You can't have a blanket law that covers every building indiscriminately. This has to be tailored," he told NBC Bay Area, listing seismic falling-hazard work and a fire-horn replacement his building has already paid for. "This is just unaffordable."

The politics have already moved. Homeowners won a five-year delay in February, pushing the deadline to secure construction permits well into the 2030s. Now a technical advisory council — supervisors, residents, Fire Department officials and builders, with Sherrill among them — is set to convene next month to decide how, or whether, the mandate is carried out. Sauter has signaled he wants it to consider alternatives to wholesale sprinklering. "If there are other improvements and upgrades that still meet the goal of fire safety but can be done in a less intrusive or more cost-sensitive way, I am very interested in that," he told the Chronicle.

Homeowner advocates note that other cities — San Diego and Houston among them — largely retreated from similar retrofit mandates. San Jose reached full compliance, but its rule reached just 11 buildings. San Francisco's touches more than ten times that. The report that was supposed to end the argument instead guaranteed it continues — now in front of a council, one building at a time.