Section 20139 Of Article 3.5. Counties From California Public Contract Code >> Division 2. >> Part 3. >> Chapter 1. >> Article 3.5.

. The board shall not pay or become liable for any extra work done on, or extra material furnished for, any building or structure in the course of performance of a contract let pursuant to this article except in accordance with Section 20142, unless the contract specifically provides for such payment or the contract is changed or modified in the manner provided for in this article.