ADU Regulations in Cupertino, California (2026)

Regulations at a glance

Local rules & notes

Subjective Design Standards: The City incorrectly requires ADUs to be 'compatible with the architectural style and materials of the principal structure,' which HCD flags as a prohibited subjective standard. Duplex ADU Limit: The City limits duplex lots to 'two ADUs per duplex lot,' failing to recognize duplexes as multifamily dwellings which may allow for higher counts (e.g., up to two detached for proposed, or more for existing) under state law. Underlying Zoning Compliance: The City requires all ADUs to comply with underlying zoning site development regulations, which HCD states violates the exemption for state-exempt ADUs (Gov Code 66323).

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

Frequently asked questions about ADU regulations in Cupertino

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

  In Cupertino, 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; Cupertino may follow state defaults or have local limits. Verify with Cupertino planning for your specific lot.

• What are the setback requirements for ADUs in Cupertino?

  In Cupertino, 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 Cupertino planning for overlay zones or design standards that could affect your site.

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

  In Cupertino, 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 Cupertino or county planning for your zone.

• Is ADU approval ministerial in Cupertino?

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

• Are there parking requirements for ADUs in Cupertino?

  In Cupertino, parking for ADUs is generally true. California law often waives parking for ADUs within a half-mile of transit or in certain historic districts. Check with Cupertino planning for your address.