Legal Question in Real Estate Law in California

No, but it was required to have a permit when built, unless it falls into one of the exemptions from permitting, such as most "Home Depot" type prefab sheds as long as no electrical is added. If it was built without a permit and is not exempt, the local building authority can just ignore it, or they can order it demolished, or can allow it to be retroactively permitted by paying a fee, having it inspected, correcting any defects found and having it reinspected. Which they choose to do if they find out about the unpermitted work is entirely up to the discretion of the agency. They rarely ignore it, however, since permit fees are a source of revenue.

It also would not need to have been permitted if it is so old that it was built before permitting. In that case, however, even though most building codes only apply to construction after the code takes effect, some things are retroactive. So while the lack of a permit for construction would not be an issue, the building not being up to minimum building standards would be. And if it was built without a permit when permits were required, and has not been upgraded with proper permits, the chances of it meeting minimum building standards are VERY slim.