San Francisco could soon consider requiring seismic retrofits of chimneys, in an effort to better prepare for a major earthquake.
Chimneys are among the first building components to fail in every California earthquake, as demonstrated in The City’s infamous 1906 temblor. That fact was also exemplified by last year’s Napa quake, in which a teenage boy was nearly crushed to death under a collapsed chimney, according to a recent report “Recommendations for Mitigation of Chimney Hazards in San Francisco” that was developed for The City’s Earthquake Safety Implementation Program.
The report noted that San Francisco does not yet have a platform to improve earthquake safety in chimneys. But providing guidance for homeowners to conduct voluntary – and in some cases mandatory – seismic retrofits of chimneys could save lives, according to the report.
“Even owners ready to do voluntary retrofit will not find guidance pre-approved for use in San Francisco; they are likely to receive inconsistent information when they ask architects, contractors, or building officials about the risk and how to address it,” the report states.
That’s why the report is recommending that San Francisco officials urge or require seismic upgrades to the four most common chimney types in The City, an effort that could cost as much as $25,000 per chimney.
Mandatory retrofits could be implemented for some 1,500 masonry chimneys on Victorian homes located next to streets or sidewalks, though other types of chimneys – like apartment building boiler masonry chimneys, patent flues and setback house masonry chimneys – would likely see voluntary retrofits or inspections recommended, per the report.
The report follows other recent efforts to better prepare San Francisco for an earthquake that seismologists are all but certain will happen in the near future. There’s a one in three chance the Hayward fault alone will produce a magnitude-6.7 or larger quake in the next three decades.
In addition to calling for seismic retrofits of soft-story buildings and evaluations of private schools, The City is preparing for such an event by requiring at an unprecedented level various seismic upgrades and evaluations of residential, commercial and educational buildings.
Rebuilding major infrastructure of the Bay Bridge and Doyle Drive to meet seismic safety standards are other major efforts to prepare San Francisco for “the big one.”