State law permits ADUs up to 1,200 sqft for detached units. 5,500–7,000 sqft typical in established Westminster neighborhoods. No minimum lot size required by state law.
16 feet for single-story detached ADUs. Up to 18 feet with roof pitch allowance. Two-story ADUs may reach 25 feet in qualifying zones under AB 1332.
4-foot minimum from rear and side property lines for new detached ADUs. No setback required for conversions of existing structures.
No additional parking required if within 0.5 miles of public transit. OCTA bus routes on Bolsa Avenue, Brookhurst Street, and Westminster Avenue qualify many properties for parking exemptions.
No owner-occupancy requirement (permanent per AB 976, effective 2025).
Estimated cost $210K–$360K. Permit fees $3.5K–$9K. Impact fees: Waived under 750 sqft.
Westminster is a culturally vibrant city of approximately 92,000 residents in central-west Orange County, best known as the home of Little Saigon — the largest Vietnamese-American community in the United States. The Bolsa Avenue commercial corridor is a nationally recognized cultural destination, drawing visitors from across Southern California for its restaurants, shops, and cultural events. Westminster's residential neighborhoods are predominantly single-family homes built in the 1960s–70s on lots typically ranging from 5,500–7,000 sqft, with flat topography ideal for ADU construction. The city's strong multigenerational family culture creates exceptional demand for ADUs as in-law suites and family housing — a demand pattern that exists alongside traditional rental demand. Westminster is served by the Westminster School District, Ocean View School District, and Huntington Beach Union High School District. The 405 and 22 freeways provide commute access to Huntington Beach, Costa Mesa, Irvine, and the broader OC/LA metro area. Westminster Mall and the Bella Terra shopping center anchor the city's retail offerings.