ADU Regulations in Santa Rosa, California (2026)

Regulations at a glance

Local rules & notes

Large Parcel Density Bonus: Parcels five acres or larger are permitted to have up to three accessory units, including an ADU, JADU, and a Guest House. Enforcement Delay Amnesty: Owners of ADUs built before January 1, 2020, can request a 5-year delay in enforcement of building standards if the correction is not necessary for health and safety. Advanced Treatment System Requirement: For properties under 0.50 acres with an existing primary residence, an Advanced Treatment System is required for the ADU's sanitation.

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

Frequently asked questions about ADU regulations in Santa Rosa

• What is the maximum ADU size in Santa Rosa, California?

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

• What are the setback requirements for ADUs in Santa Rosa?

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

• What is the maximum height for an ADU in Santa Rosa?

  In Santa Rosa, 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 Santa Rosa or county planning for your zone.

• Is ADU approval ministerial in Santa Rosa?

  In Santa Rosa, 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; Santa Rosa planning can confirm the exact process.

• Are there parking requirements for ADUs in Santa Rosa?

  In Santa Rosa, 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 Santa Rosa planning for your address.