Pre-Approved ADU Plans in Orange County

Pre-approved building plans saved builders an average of $10,300 in design and related costs and shortened the design and permitting process by about 53 days, according to a survey of California cities by UCR's Center for Community Solutions. Cities also reported preapproved plans were processed an average of 2.8 times faster than conventional building plans. Most of the preapproved plans offered by responding communities were for accessory dwelling units, with about 500 ADUs permitted or constructed using preapproved plans.

Under California Government Code section 65852.27, added by Assembly Bill 1332, every city and county was required to have a program for preapproving ADU plans by January 1, 2025. For a detached ADU that uses a plan the agency preapproved within the current triennial building code cycle, the agency must approve or deny a complete application within 30 days. Other ADU permits get 60 days from a complete application when a home already exists on the lot, under Government Code section 66317.

In Orange County, the County and 11 cities had plan sets posted when checked in October 2026. Available plans range from compact studios to multi-bedroom layouts, such as Santa Ana's selection ranging from a 399-square-foot studio to a 749-square-foot two-bedroom unit.

Avorino serves 37 Orange County cities and communities: Aliso Viejo, Anaheim, Brea, Buena Park, Corona del Mar, Costa Mesa, Coto de Caza, Cypress, Dana Point, Fountain Valley, Fullerton, Garden Grove, Huntington Beach, Irvine, La Habra, La Palma, Ladera Ranch, Laguna Beach, Laguna Hills, Laguna Niguel, Lake Forest, Las Flores, Los Alamitos, Mission Viejo, Newport Beach, Orange, Placentia, Rancho Santa Margarita, Rossmoor, San Clemente, San Juan Capistrano, Santa Ana, Stanton, Tustin, Villa Park, Westminster and Yorba Linda. For a complimentary project consultation over Zoom, book a free call.