Is an air admittance valve a code requirement in CA?

In California, air admittance valves (AAVs) are permitted under specific circumstances, but they are not universally required by code. The California Plumbing Code allows their use as an alternative to traditional venting methods in certain applications, provided they meet specific criteria and are installed correctly. However, local jurisdictions may have their own regulations regarding AAVs, so it's essential to consult local building codes and regulations for compliance.