The classic California suburb — rows of houses, each with their own yard and fence — is largely a product of something called single-family zoning, a regulation that dictates that there can be only one house per parcel of land. These laws prohibit, say, building a high-rise in a residential cul-de-sac.
S.B. 9 essentially ends single-family zoning, but with a modest shift: Under the bill, property owners can build up to three additional units on their land, allowing single-family homes to be transformed into as many as four units.
A recent analysis by the Terner Center for Housing Innovation at University of California, Berkeley, found that S.B. 9 would most likely lead to 714,000 new homes across the state over the next several years.
What previous housing laws did
Though symbolically significant, S.B. 9 may not actually be as impactful as changes to housing policy that have already been enacted, Conor told me.
State lawmakers have been passing numerous housing reforms over the past four years in an effort to boost housing production. (Gov. Jerry Brown signed 15 housing bills in 2017, and Newsom signed 18 in 2019.)
Perhaps most significantly, California in 2017 relaxed laws to make it easier for homeowners to convert and rent out accessory dwelling units, the technical term for backyard homes — think “granny flats” or “in-law apartments.” Those rules have been further loosened since.
So even before S.B. 9 appeared on the scene, homeowners in California were allowed to have two units on a single-family lot — a main house and a separate guesthouse.