ADU Regulations in Fullerton, California (2026)

Regulations at a glance

Local rules & notes

10-Year Amnesty for Substandard ADUs: Building officials must approve a delay of not less than 10 years for enforcement of building standards on substandard ADUs if they do not present an imminent risk to health and safety. Deemed Approved Mechanism: Applications not acted upon within 60 days are deemed approved, a stricter standard than the previous 120-day review. Impact Fee Exemption: ADUs are not considered a new residential use for calculating fees, effectively waiving connection and capacity charges.

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

Frequently asked questions about ADU regulations in Fullerton

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

  In Fullerton, the maximum ADU size is typically 1200 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; Fullerton may follow state defaults or have local limits. Verify with Fullerton planning for your specific lot.

• What are the setback requirements for ADUs in Fullerton?

  In Fullerton, typical setback requirements are 3 feet from the side property line and 3 feet from the rear. These may be reduced to 4 feet under California Government Code § 65852.2 where applicable. Check with Fullerton planning for overlay zones or design standards that could affect your site.

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

  In Fullerton, 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 Fullerton or county planning for your zone.

• Is ADU approval ministerial in Fullerton?

  In Fullerton, 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; Fullerton planning can confirm the exact process.

• Are there parking requirements for ADUs in Fullerton?

  In Fullerton, 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 Fullerton planning for your address.