Setting the standards for new buildings is one thing. Prodding building owners to retrofit their structures for seismic safety is a much different task one that San Francisco has been working on for the past 30 years.

The impetus, obviously, was the Loma Prieta earthquake of Oct. 17, 1989, that killed 67 people and, in San Francisco, destroyed or damaged more than 6,000 housing units. Downtowns towers came through with little damage, but wooden apartment buildings in the Marina collapsed, as did several brick structures South of Market.

In 1992, an ordinance focused on masonry buildings lacking seismic reinforcement was the first citywide regulation to get owners to upgrade their buildings. At the time, there were nearly 2,000 such structures in the city. After a mix of official deadlines and financial incentives, 95% had been upgraded by 2008.

Now, just 11 masonry structures remain out of compliance. Five are owned by the city: One is being renovated, two will be replaced with low-income housing and two will be restored as part of the Pier 70 development.

Scrutiny is currently on soft-story buildings structures where the ground floor has such large openings that they lack the strength to support the upper floors should a major temblor hit.

Nearly 5,000 buildings containing roughly 48,000 units of housing were classified this way in 2014, when the city made it mandatory to bring structures up to seismic code. Vulnerable structures containing 15 or more housing units were required to have all work done by August 2018, while smaller residential buildings had until this August to comply.

As of last month, 76% of the targeted soft-story structures are in compliance. Most of those remaining have received permits or are in the process.

One hurdle, say city officials, is the local economy. It can be hard for building owners to find contractors who arent busy. Or contractors submit such high bids that owners face a financial bind.

The fact that were doing this well in this (economic) environment, were excited, said Brian Strong, San Franciscos chief resilience officer. Well need to see how compliant we are overall in another year or two.

Berkeley started its own soft-story effort nearly a decade earlier, with a 2004 ordinance to encourage upgrades by owners of the 337 buildings with a soft-story classification. Retrofits were made mandatory in 2014.

Now, only 51 such buildings in Berkeley remain out of compliance. Of these, 43 owners have either applied for or received building permits to begin work.

Oakland started a similar effort this year, sending out notices to the owners of nearly 1,500 soft-story residential buildings that may be vulnerable. The deadline to bring structures up to code is in four to six years, depending on the buildings size and whether it contains affordable housing.

John King is a San Francisco Chronicle staff writer. Email: jking@sfchronicle.com Twitter: @JohnKingSFChron

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Earthquake retrofits Bay Area making progress, but still more to do - San Francisco Chronicle