California Code, Civil Code - CIV § 901

A builder may, but is not required to, offer greater protection or protection for longer time periods in its express contract with the homeowner than that set forth in Chapter 2 (commencing with Section 896). A builder may not limit the application of Chapter 2 (commencing with Section 896) or lower its protection through the express contract with the homeowner. This type of express contract constitutes an “enhanced protection agreement.”