California State License Board classification B — General Building Contractor — required for any construction that involves more than two unrelated trades.
ADU construction always requires a B-license general contractor (or the related B-2 residential remodelling specialty). Anyone offering to build your ADU should be verified at the CSLB Instant License Check before signing.
Part of the BackyardADU California ADU Glossary — plain-English definitions of the regulatory, construction, and financing terms you'll encounter during a California ADU project.