Some 2,800 so-called soft-story buildings -- wooden structures built before 1973 with a home above a store or garage -- are considered most at risk.
Newsom's proposal would allow property owners to borrow repair money at a reduced rate by creating a special tax district. That would require approval by the board of supervisors.
The mayor also wants to shift part of $280 million in unspent bond money designated for retrofitting unreinforced masonry buildings. Transferring that money would require voter approval, and Newsom said he hopes to put that on the November ballot for voter approval.
Although there are about 4,400 soft-story buildings in San Francisco, an analysis by the city controller's office found that few owners have taken advantage of the city's program to waive certain fees because the savings is only a fraction of the total cost.
Janan New, executive director of the San Francisco Apartment Association, a landlord group, warned that mandatory retrofitting could force some businesses to close for weeks and even months, possibly driving some out of business altogether.
