ADU Regulations in Walnut Creek, California (2026)

Regulations at a glance

Local rules & notes

Construction Sequencing Requirement: Detached ADUs that exceed 800 square feet of floor area must be constructed prior to any other ADUs on the lot. Pre-Reviewed ADU Plans (PRADU) Program: The city provides a library of pre-reviewed plans for detached new construction ADUs to streamline review and reduce costs. Faith-Based ADU Proactivity: The city is recognized by HCD for its proactive approach to allowing ADUs on faith-based organization properties.

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

Frequently asked questions about ADU regulations in Walnut Creek

• What is the maximum ADU size in Walnut Creek, California?

  In Walnut Creek, the maximum ADU size is typically 800 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; Walnut Creek may follow state defaults or have local limits. Verify with Walnut Creek planning for your specific lot.

• What are the setback requirements for ADUs in Walnut Creek?

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

• What is the maximum height for an ADU in Walnut Creek?

  In Walnut Creek, 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 Walnut Creek or county planning for your zone.

• Is ADU approval ministerial in Walnut Creek?

  In Walnut Creek, 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; Walnut Creek planning can confirm the exact process.

• Are there parking requirements for ADUs in Walnut Creek?

  In Walnut Creek, 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 Walnut Creek planning for your address.