ADU Regulations in Brentwood, California (2026)

Regulations at a glance

Local rules & notes

Illegal JADU Replacement Parking: The city ordinance requires replacement parking when an attached garage is converted to a JADU. HCD cites this as a violation of Gov Code 66334(a) and orders its removal. Non-compliant Attached ADU Size Limit: The ordinance limits attached ADUs to 50% of the primary dwelling's floor area. HCD flagged this as non-compliant because it did not explicitly permit a minimum of 800 sq ft regardless of the percentage. Bedroom-Based Size Caps: The city imposes specific square footage caps based on bedroom count (850 sq ft for studio/1-bed, 1000 sq ft for 2+ beds), which is more granular than standard state defaults.

For the official ordinance and latest updates, check your city or county planning department.

Frequently asked questions about ADU regulations in Brentwood

• What is the maximum ADU size in Brentwood, California?

  In Brentwood, the maximum ADU size is typically 1000 square feet, depending on whether the unit is attached or detached. California state law allows up to 1,200 sq ft for detached ADUs and 800 sq ft for attached in many jurisdictions; Brentwood may follow state defaults or have local limits. Verify with Brentwood planning for your specific lot.

• What are the setback requirements for ADUs in Brentwood?

  In Brentwood, typical setback requirements are 4 feet from the side property line and 4 feet from the rear. These may be reduced to 4 feet under California Government Code § 65852.2 where applicable. Check with Brentwood planning for overlay zones or design standards that could affect your site.

• What is the maximum height for an ADU in Brentwood?

  In Brentwood, the maximum height for an ADU is generally 16 feet. State law often allows up to 16 feet for detached ADUs and up to 25 feet when within 4 feet of the property line in some cases. Confirm with Brentwood or county planning for your zone.

• Is ADU approval ministerial in Brentwood?

  In Brentwood, ADU approval is typically Ministerial (by-right) per Gov Code §65852.2. Ministerial (by-right) review means the city must approve qualifying applications without discretionary review, per California Gov Code § 65852.2. Your project must still meet objective standards; Brentwood planning can confirm the exact process.

• Are there parking requirements for ADUs in Brentwood?

  In Brentwood, parking for ADUs is generally Often waived per state law; check local ordinance. California law often waives parking for ADUs within a half-mile of transit or in certain historic districts. Check with Brentwood planning for your address.