As of June 18, 2013, if you own a residential building of a certain size in San Francisco, you’ll be required to seismically retrofit it. The law specifically applies to wood frame buildings with “soft stories,” which means buildings with three or more stories, or two stories above a basement or underfloor area that has any portion extending above grade. The buildings must contain five or more units to comply with the new rules.
Ivan Diviney, owner of Diviney Construction Inc., a Diamond Certified company, explains why soft story buildings are so dangerous: “During an earthquake, large openings on the ground floor (like garage doors or commercial spaces with large window and door openings) are especially vulnerable. These openings have no shear structure to stop a ‘soft story’ from failing, which means residents who live above them are at high risk. Even if the upper floor is structurally sound, the base of the building isn’t, so gravity will take its course.”
It’s imperative that you hire a competent and experienced contractor who specializes in foundation work to handle your retrofit. According to Jerry Deasy, owner of Gaelic Construction, a Diamond Certified company, any retrofit project should start with a thorough assessment to check the levels of your home. “Determining what needs to be done to strengthen the structure depends on a number of factors,” he says. “For example, you have to look at where the building is in San Francisco and consider the soil, the height of the structure, and the adjacent buildings. One big problem I find is many buildings don’t have footings to support them, or the footings aren’t set deep enough to stabilize them in case of an earthquake.”
Some buildings are exempt from the new requirements, including those that have been seismically strengthened within 15 years of the law’s effective date. For many more details on the exemptions, permit process and what you can do if you can’t afford the mandatory improvements, go to www.sfgsa.org.