Costa Mesa, CA Accessory Structures: Shed Rules (2026)

Storage sheds on residential property in Costa Mesa are regulated through the Building Code (Title 12) and Zoning Code (Title 13). Under the California Building Code as adopted by Costa Mesa, detached accessory structures not exceeding 120 square feet in floor area and of one-story construction are generally exempt from building permit requirements, though they must still comply with zoning standards. Sheds requiring permits include those exceeding 120 square feet, those with plumbing or electrical service, and those intended for use as workshops or hobby rooms. In the R1 Single-Family Residential zone, accessory structures not exceeding 6.5 feet in height may be placed with a zero rear yard setback, making them ideal for compact shed placement along the back property line. Taller sheds must meet the standard 3-foot interior side yard setback and 10-foot rear yard setback for the R1 zone. All sheds count toward the lot's maximum lot coverage, so homeowners must verify they have sufficient coverage allowance before adding a shed. Sheds may not be placed in the front yard or required front setback area. They may not be used for human habitation, commercial storage unrelated to the residential use, or any activity that generates noise, odor, or nuisance conditions. Prefabricated sheds delivered and placed on the property are still subject to zoning standards even if they are exempt from building permits. Sheds placed on permanent foundations or connected to utilities typically require building permits regardless of size.