(a) Except as provided in subdivision (b), the agency shall only issue rehabilitation loan loss guarantees on single-family homes or on buildings with five or more residential units and where any commercial use in those buildings is limited to the basement and ground floors or where the commercial use occupies less than 15 percent of the total square footage of the building.
(b) For the purpose of using the program enacted by this chapter in conjunction with the multifamily seismic retrofit program authorized by Section 50668.5, the 15-percent limitation on commercial space required by subdivision (a) may be waived in order to facilitate the seismic retrofit of lower income housing.