I do not live in California nor do I know the building codes, but I would expect the information to be readily available from the local codes department. Depending on how close the homes are to their neighbors, means of egress, and other determining factors, building codes can vary city to city. Different wall ratings may be required. Good luck in your search. Sorry I couldn't be more specific in my answer.
Jessica recommends the following next steps:
- Visit local building codes website or office.