ADU Regulations in Simi Valley, California (2026)

Regulations at a glance

Local rules & notes

Measure N Growth Control Exemption: ADUs and JADUs are exempt from the City's Residential Building Permit Allocation System, allowing them to bypass growth control queues. Conversion Expansion Allowance: Existing accessory structures being converted to ADUs may be expanded by up to 150 square feet to accommodate ingress and egress. Horse Stable Conversion: The ordinance explicitly lists horse stables as a type of accessory structure that can be converted into a detached ADU.

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

Frequently asked questions about ADU regulations in Simi Valley

• What is the maximum ADU size in Simi Valley, California?

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

• What are the setback requirements for ADUs in Simi Valley?

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

• What is the maximum height for an ADU in Simi Valley?

  In Simi Valley, 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 Simi Valley or county planning for your zone.

• Is ADU approval ministerial in Simi Valley?

  In Simi Valley, 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; Simi Valley planning can confirm the exact process.

• Are there parking requirements for ADUs in Simi Valley?

  In Simi Valley, 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 Simi Valley planning for your address.