ADU Regulations in South San Francisco, California (2026)

Regulations at a glance

Local rules & notes

Sewer Video Requirement: A sewer video is required for most ADUs to check line integrity, with potential repair costs ranging from $10,000 to $20,000. Converted Unit Expansion: Converted ADUs are permitted an expansion of up to 150 sq. ft. specifically to accommodate ingress/egress or habitability requirements. High Building Permit Fees: Building permit fees are estimated at a high rate of approximately 10% of the project valuation.

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

Frequently asked questions about ADU regulations in South San Francisco

• What is the maximum ADU size in South San Francisco, California?

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

• What are the setback requirements for ADUs in South San Francisco?

  In South San Francisco, 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 South San Francisco planning for overlay zones or design standards that could affect your site.

• What is the maximum height for an ADU in South San Francisco?

  In South San Francisco, the maximum height for an ADU is generally 18 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 South San Francisco or county planning for your zone.

• Is ADU approval ministerial in South San Francisco?

  In South San Francisco, 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; South San Francisco planning can confirm the exact process.

• Are there parking requirements for ADUs in South San Francisco?

  In South San Francisco, 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 South San Francisco planning for your address.