A metal storage shed went up in a rented Fresno back yard last spring. The inspector who came out on May 30, 2025 never got into that back yard at all, and wrote in the case file anyway that the added shed was “well over the allowed 120 square feet.”
That number is the one most people have heard, and most have heard it slightly wrong. It is where California’s statewide permit exemption for a detached accessory structure stops. It is not a promise that anything under it is fine, and it is not necessarily the number your own city uses.
What actually happens
Section 105.2 of the 2025 California Building Code, effective statewide January 1, 2026, exempts one-story detached accessory structures “used as tool and storage sheds, playhouses and similar uses” where the floor area is not greater than 120 square feet.
The sentence above that list does more work than the list. An exemption does not authorize work done in violation of “any other laws or ordinances of this jurisdiction.” Setbacks, height limits and zoning do not go away because a building permit did…