Oakland weighs ordering retrofits
Mandate would apply to soft-story buildings
Oakland may soon require hundreds of old apartments to be seismically retrofitted in an effort to prevent a mass collapse of buildings in the next big earthquake.
The retrofit rules would apply to soft-story residential buildings: multiunit, woodframe structures with weak first stories built before 1991. An apartment with garage parking in the ground floor or street-level retail could fall into the targeted category.
Such buildings are prone to collapse during earthquakes, when the combined weight of shaken upper levels becomes too much for the vulnerable first story, as Loma Prieta proved in 1989 and Northridge in 1994.
“You look at photos of (San Francisco’s) Marina District after ’89 — quite a few buildings looked like three stories when they used to be four,” said Thor Matteson, a structural engineer of the Bay Area firm Quake Bracing.
Oakland is believed to have more than 24,000 housing units in 1,400 to 2,800 softstory buildings, defined as those with at least five units and two to seven stories, according to city estimates. The first step of the ordinance proposed by City Councilman Dan Kalb and Mayor Libby Schaaf involves finding out which buildings must be retrofitted and which are exempt, such as those that have already completed the work.
Building types would be divided into three tiers, and each category would be on a different timetable. Owners would have four to six years to complete the retrofit work.
“If we don’t increase the integrity of the buildings, not only will we have loss of life, but massive displacement,” Kalb said. “We’re not prepared for that. No city is prepared for that.”
The proposal was based on similar ordinances in nearby cities. The Bay Area has roughly 140,000 housing units in 18,000 soft-story buildings, according to the Association of Bay Area Governments.
Cities including San Francisco and Berkeley are several years ahead of Oakland in mandating soft-story retrofits. San Francisco passed its law in 2013, and the program is supposed to wrap up in 2020, although hundreds of landlords dragged their feet on complying with deadlines. Berkeley’s law took effect in 2014, and retrofit work is supposed to be completed by the end of this year. Los Angeles began its program in 2016, and it will end in 2024. San Jose does not require soft-story retrofits, but officials there are considering doing so.
Officials in Oakland started working on the proposal four years ago, but it “wasn’t on the front burner” in recent years, Kalb said. Legislation stemming from the housing crisis — impact fees, tenant protections and a massive bond — took precedence, he said.
Experts and public officials say it’s only a matter of time before a catastrophic earthquake erupts along the Hayward Fault, which bisects the city. The past five large quakes on the fault came at roughly 140-year intervals, and the last one happened 150 years ago.
Despite the apparent imminence, Kalb and others say the timing for Oakland to enact the retrofit requirement now is actually beneficial.
“San Francisco and Berkeley are doing 5,000 of these right now,” said David Bonowitz, a structural engineer who advised Oakland officials on the proposed ordinance. “It means the contractors and engineers are trained, and there’s a good market with lots of supply.”
Heidi Tremayne, executive director of the Oakland-based Earthquake Engineering Research Institute, said Oakland officials took advantage of lessons learned from policies and planning of other cities. Engineers and contractors have gotten “upskilled” by other programs, she said.
Darin Ranelletti, Schaaf ’s policy director for housing security, said the pace of the program, in which some owners would have six years to make the fixes, is necessary because of the number of buildings and tenants involved. He said the city plans to hire 11 new building inspectors.
Oakland previously instituted a voluntary retrofit ordinance and screening program. This one — which will go to the full City Council on Tuesday — would be mandatory.
Under the proposal, up to 70 percent of the costs of the retrofit could be passed on to tenants over a 25-year period. Tenants forced to move out while the work is done would be eligible for relocation payments from owners, who can apply for financial assistance from the city, which received grant money from state and federal programs.
Kalb said temporary displacement of some tenants would be dwarfed by the crisis-level homelessness that is expected to follow a big earthquake absent a widescale seismic retrofit program.
Many soft-story buildings have hazards beyond their weak first floors. Asymmetric configuration — a normal wall in the back but a wideopen front, for instance — can lead to a building twisting or rotating during an earthquake, said Khalid Mosalam, a UC Berkeley structural engineering professor and director of the Pacific Earthquake Engineering Research Center.
“Soft-story buildings are a known vulnerability of residential homes. We know that because of past experiments we have done, past modeling and simulation, but also because of observation after earthquakes,” he said. “You can end up with cascading failures in gas lines, electric lines, and God forbid you have a fire after an earthquake.”
Other common problems in soft-story apartment buildings, because of their age, come from environmental deterioration — things like moisture buildup or termite infestations, Mosalam said.
Because of those additional risks, if the ordinance passes, city inspectors will also be noting code violations that owners would be required to fix.
The proposed ordinance includes some incentives for property owners. One is a “housing bonus” in which owners can add an additional one to two apartment units. The idea is to help them offset the costs of the work by opening up another stream of rental income, which also helps the city increase housing supply, Ranelletti said.
Retrofit design and construction can cost tens of thousands of dollars. James Gillett, a building contractor and president of Earthquake Construction Service in Oakland, recommended that property owners shop around for estimates. Bonowitz, the city adviser, encouraged landlords to get references from engineers and contractors and ask for examples of their work.
“This is not a kitchen or bath remodel,” Bonowitz said.
Seismic retrofits vary by building. The work often involves strengthening existing walls with plywood or adding a steel moment frame around a garage door.
“The things we’re talking about are basic engineering,” Bonowitz said. “You take a building that’s collapse prone and make it not collapse prone. We have high confidence that these are going to be much, much better.” Kimberly Veklerov is a San Francisco Chronicle staff writer. Email: kveklerov@ sfchronicle.com Twitter: @kveklerov