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ADU law: rentals without a rezoning
Add accessory homes to houses and apartment properties by right, with capped setbacks, little or no parking, and no impact fees on small units.
California ADU law lets an existing apartment property add up to eight detached ADUs (no more than the number of existing units) plus conversions of unused space up to 25% of the unit count, by right and with 60-day ministerial approval. A single-family lot can add a detached ADU, a converted ADU and a junior ADU.
What it gets you
- A single-family lot can add a detached ADU, a converted ADU and a junior ADU of up to 500 sf.
- Cities cannot cap ADU size below 850 sf, or 1,000 sf with two or more bedrooms, and must allow at least 800 sf regardless of lot coverage or FAR.
- Heights of 16 ft detached, 18 ft near transit or beside a multistory building, and 25 ft attached.
- No parking within half a mile of transit, and no replacement parking when a garage or carport is converted.
- No owner-occupancy requirement for ADUs.
- New multifamily projects can include two detached ADUs that don't count against density.
The catches
- ADUs generally can't be sold apart from the main property unless your city has adopted AB 1033 condo rules.
- The eight-ADU allowance can't exceed the number of existing units on the lot.
- Fees on ADUs of 750 sf and larger are charged in proportion to the main home's size.
- Rentals must be longer than 30 days where the city restricts short-term rentals.
- Fire separation, utility capacity and accessibility drive cost more than zoning does.
- Timing matters: a new multifamily project can include up to two detached ADUs, while an existing building can add up to eight plus conversions. Plan the sequence before the first filing.
How we help
- Site audits of apartment properties that count every allowed ADU, including conversions owners overlook.
- Repeatable ADU plans that can be permitted once and built across a portfolio.
- ADU components designed into new multifamily communities in Riverside and Rialto.
Gov. Code §§ 66310–66342
Questions we get about ADUs
How many ADUs can I add to an existing apartment building?
Up to eight detached ADUs under SB 1211, but no more than the number of existing units, plus conversions of storage, garages or attics up to 25% of the existing unit count.
Can a new multifamily project include ADUs?
Yes. A new multifamily project can include up to two detached ADUs that don't count against density. Once the building exists, it can add more under the existing-multifamily rules, so the sequence of filings matters. On Pickford Street, a four-unit building became six with two ADUs added after construction.
Do ADUs require parking in California?
Not within a half mile of transit, and no replacement parking is required when a garage or carport is converted to an ADU.
Do ADUs pay impact fees?
ADUs under 750 sf pay no impact fees. Larger ADUs are charged in proportion to the main home's size.
Can ADUs be sold separately?
Generally no, unless your city has adopted condominium rules under AB 1033.
Is owner occupancy required to build an ADU?
No. State law does not require owner occupancy for ADUs.
Projects where we used it
- Pickford Street, Los AngelesCase study
- Pacific Avenue, Long BeachCase study
This page is general information, not legal advice. It summarizes California law as of October 2026. Cities adopt their own implementing ordinances, and eligibility depends on site-specific facts. Confirm with the local planning department and your land use counsel before acquiring a site.
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Tell us where the site is and what you are hoping to build. We will tell you which of these laws applies and roughly how many homes it can hold.