Kevork Djansezian, File, Associated Press
FILE - In this Jan. 18, 1994, file photo, California National Guardsman walk past a Hollywood apartment building damaged by a deadly earthquake in Los Angeles. The Los Angeles City Council is expected to pass a retrofitting law Friday, Oct. 9, 2015, requiring costly upgrades of thousands of older wood and concrete apartment buildings that would be vulnerable to collapse in a major earthquake.

LOS ANGELES — Thousands of older wood and concrete apartment buildings that would be vulnerable to collapse in a major earthquake would get costly upgrades under sweeping retrofitting rules passed Friday by the Los Angeles City Council.

The mandate would affect as many as 13,500 so-called soft-first-story buildings, which are typically wood-frame structures with large spaces such as parking lots on the ground floor. As many as 1,500 brittle concrete buildings would also require upgrades.

The measure passed on a 12-0 vote.

"There's no question that we're going to have an earthquake. The question is, when?" Councilman Gil Cedillo said before the vote. "In here we've laid out the groundwork for the seismic retrofitting that needs to be done."

City leaders will now have to agree on how the estimated $5,000-per-unit retrofitting costs would be split between tenants and landlords. One proposal is to split the costs 50-50 and cap possible monthly rent increases at $38.

Before the vote, representatives for residential landlords and commercial building owners signaled their approval of the plan — while expressing concerns about potential costs.

The proposed quake retrofitting mandate is part of an effort by Mayor Eric Garcetti to make the city resilient to major earthquakes. His plan released in December focuses on rapidly identifying and retrofitting at-risk residential and commercial buildings, fortifying major water systems that would be severed by a huge quake and keeping telecommunications systems operating.

Wood apartments will be given seven years to complete construction once an owner is ordered by the Department of Building and Safety to retrofit the building. Owners of brittle concrete buildings will have 25 years to do the work.

Sixteen people were killed in the collapse of a soft-first-story building during the Jan. 17, 1994, Northridge earthquake. The magnitude-6.7 jolt was the last significant seismic disaster in the Los Angeles region.