Two detached ADUs: what changes in 2027
California is opening another option for homeowners who want more than one backyard home.
Effective January 1, 2027
A second detached unit becomes possible
AB 956 expands the state approval route for new detached ADUs on qualifying single-family properties from one unit to two. The bill was signed on September 29, 2026, and takes effect January 1, 2027.
A detached ADU is a separate home on the same property as the main house. This change could give an owner room for two smaller homes instead of one backyard unit.
Two units still need a workable site plan
Under this route, cities may limit each unit to 800 square feet of living space. Four-foot side and rear setbacks, applicable height limits, and building and fire-safety requirements still matter. The law does not mean every yard can accommodate the same layout.
If two detached ADUs are built under this provision, the City does not have to approve a junior ADU on the same lot.
Compare layouts before committing to a design
Ask your designer to compare one larger unit with two smaller units. Look at access, outdoor space, utility routes, and how construction would affect the main home. Two front doors also mean two households need a practical way to use the property.
For a 2027 application, contact your City Planning Department about submitting a two-unit proposal. Bring a property address and a simple site sketch. These are planning steps, not a guarantee that a particular design will qualify.
