Multi-family ADUs: add one or two units to your property.

ADUs for multi-family properties

California ADU law allows two types of ADUs on any multi-family property. A detached ADU is a free-standing building separate from the main building. A conversion ADU transforms existing non-livable space — storage rooms, recreation rooms, garages or carports — into a home.

Why add ADUs to a multi-family property?

ADUs aren’t only for single-family homes. Adding detached units or converting underused garage or storage space increases overall property value and creates additional rental income — a strong way to maximize a property’s rental potential, including on duplexes and new construction.

How many ADUs can I build?

It depends on what’s on the property today. Since January 2025, up to eight detached ADUs are allowed alongside an existing multi-family building. At least one conversion ADU is always allowed, up to 25% of the number of existing units.

Are there special regulations?

Detached ADUs may be limited to 16 feet in height, though some cities allow up to 25 feet (two stories). Minimum setbacks are 4 feet at the rear and sides. Maximum size varies by city, but you can always build at least 800 sq ft. Conversion ADUs inside the main building follow that building’s requirements — if it has fire sprinklers, the ADU will too.

Does parking need to be replaced or provided?

No replacement parking is required when converting a garage or carport. New detached ADUs don’t require on-site parking if the property is within half a mile of public transit, including bus stops.