ADU Regulations in Half Moon Bay, California (2026)

Regulations at a glance

Local rules & notes

Illegal Ban on Garage Conversions in Ocean Colony: The City ordinance specifically prohibits ADUs in garages within the Ocean Colony district. HCD explicitly states this violates Government Code section 66323. Subjective Design Review Standards: The ordinance requires ADUs to use 'similar' materials to the primary dwelling. HCD rules this term subjective and non-compliant; standards must be objective. Illegal Parking Replacement Requirement: The ordinance requires replacement of parking spaces if a garage is demolished for an ADU. HCD states this violates State Law which prohibits such requirements. Concurrent Processing Denial: The ordinance does not allow concurrent processing of ADU permits with new single-family home permits. HCD mandates 60-day concurrent review.

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

Frequently asked questions about ADU regulations in Half Moon Bay

• What is the maximum ADU size in Half Moon Bay, California?

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

• What are the setback requirements for ADUs in Half Moon Bay?

  In Half Moon Bay, 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 Half Moon Bay planning for overlay zones or design standards that could affect your site.

• What is the maximum height for an ADU in Half Moon Bay?

  In Half Moon Bay, 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 Half Moon Bay or county planning for your zone.

• Is ADU approval ministerial in Half Moon Bay?

  In Half Moon Bay, 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; Half Moon Bay planning can confirm the exact process.

• Are there parking requirements for ADUs in Half Moon Bay?

  In Half Moon Bay, 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 Half Moon Bay planning for your address.