What impact will SB 9 and SB 10 have?

Californians are aware that single-family zoning has significantly restricted the construction of housing. In recent years, the state has made it easier for homeowners to build backyard additions to rent out. Extending this, SB 9 allows homeowners to build a duplex on their parcel, as well as creating a process to split lots into two parcels if each is at least 1,200 square feet. Each side is eligible to have a duplex or a home-addition combo and these must be approved ministerially. No more than four units can occupy one property. Applications for both follow objective standards, such as protections for existing renters, and avoid discretionary review in front of the Planning Commission. SB 9 enables homeowners who live on the property for at least three years afterwards the flexibility to add income-producing long term rental units or places for family members to live independently at different stages of their life.

SB 10 creates a process by which the city council can increase the density in residential areas up to 10 units per lot in a jobs-rich area, or on land near public transit, or in areas of urban infill. The resolution can specify the height limit and it can bypass the typical environmental review process when rezoning.

The Terner Center at UC Berkeley suggests SB 9 could increase the housing stock in California by about 700,000 over the next decade. As building additional units is voluntary, the number will depend on landowners being willing to reconfigure their properties. Cities are required to approve these proposals if they meet the specified size requirements and design standards.