Senator Scott Wiener (D-San Francisco) recently introduced Senate Bill 478 and Senate Bill 477. These bills join previously introduced Senate Bill 10 and Senate Bill 234 to complete the senator’s 2021 housing package.

SB 478, the Housing Opportunity Act, ensures that local zoned density and state housing laws are not undermined by hyper-restrictive lot requirements that make it nearly impossible to build multifamily buildings in areas zoned for those types of structures. Specifically, SB 478 sets minimum standards on floor area ratios (FAR) and minimum lot sizes for land zoned for missing middle housing (from duplexes to 10-unit buildings).

Excessively low FAR and large minimum lot sizes are tools that numerous cities use to undermine zoned density. In other words, a city can zone for multi-unit housing (or state law authorizes multi-unit housing) but extreme FAR or lot size requirements make that zoned density effectively impossible. As a result, cities are able to use this loophole to prohibit multi-unit housing otherwise authorized by local or state zoning law, says Wiener.

Current state law already pre-empts local FAR regulations from hindering the production of ADUs. When building an ADU, local FAR standards are void. SB 478 would simply require an FAR of 1.5 on multifamily zoned lots rather than completely nullify them as is the case with ADUs.