ADU rules in Brentwood, CA — also called accessory dwelling unit regulations or granny flat ordinances — cover setbacks, owner-occupancy, parking, and permit requirements.
Brentwood must allow Accessory Dwelling Units on any single-family lot under California Government Code Section 65852.2, as expanded by AB 68, AB 881, and SB 13. Detached ADUs up to 800 sq ft with 4-foot setbacks are ministerial approvals processed within 60 days. AB 1033 now allows selling an ADU separately from the primary home.
California preempts local ADU restrictions through Government Code Section 65852.2 and a series of reform laws. Brentwood must ministerially approve, within 60 days of a complete application, an ADU of at least 800 square feet with 4-foot side and rear yard setbacks, 16-foot height (or taller in some cases), and no parking requirement when the parcel is within 1/2 mile of public transit or a car-share. Junior ADUs up to 500 square feet within the existing primary dwelling are separately allowed and require only an efficiency kitchen and may share a bathroom. Owner-occupancy requirements were suspended statewide through 2025 under SB 13 and extended for certain ADU types. Impact fees are prohibited on ADUs under 750 square feet, and utility connection fees must be proportional to size. AB 1033 (2024) authorizes cities to allow ADUs to be sold separately as condominiums if the local agency opts in. Short-term rental of ADUs (under 30 days) is prohibited on ADUs permitted after January 1, 2020 in many jurisdictions and Brentwood imposes this restriction. Applicants submit plans through the Community Development Department, with ministerial review bypassing CEQA and public hearings. Rental of ADUs for 30+ days is explicitly permitted regardless of HOA rules (Civil Code Section 4751).
Contact your local code enforcement office for specific penalty information.
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Side-by-side rule comparisons with other cities in Contra Costa County.
See how other cities in Contra Costa County handle adu rules.
See how Brentwood's adu rules rules stack up against other locations.
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