ADU Regulations in Rancho Santa Margarita, California (2026)

Regulations at a glance

Local rules & notes

Unlawful Unit Combination Restrictions: The city's ordinance incorrectly limited single-family lots to only one ADU and one JADU, whereas state law allows a converted ADU, a detached ADU, and a JADU simultaneously. Illegal Replacement Parking for JADU Garage Conversions: The city attempted to require replacement parking for the primary dwelling when a garage is converted to a JADU, which is prohibited by state law. Incorrect JADU Rental Term Minimums: The city tried to mandate a 30-day minimum rental term for JADUs, but HCD found that Government Code section 66333 does not allow this restriction for JADUs.

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

Frequently asked questions about ADU regulations in Rancho Santa Margarita

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

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

• What are the setback requirements for ADUs in Rancho Santa Margarita?

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

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

  In Rancho Santa Margarita, 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 Rancho Santa Margarita or county planning for your zone.

• Is ADU approval ministerial in Rancho Santa Margarita?

  In Rancho Santa Margarita, 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; Rancho Santa Margarita planning can confirm the exact process.

• Are there parking requirements for ADUs in Rancho Santa Margarita?

  In Rancho Santa Margarita, parking for ADUs is generally false. California law often waives parking for ADUs within a half-mile of transit or in certain historic districts. Check with Rancho Santa Margarita planning for your address.