California Code, Business and Professions Code - BPC § 7057

(a) Except as provided in this section, a general building contractor is a contractor whose principal contracting business is in connection with any structure built, being built, or to be built, for the support, shelter, and enclosure of persons, animals, chattels, or movable property of any kind, requiring in its construction the use of at least two unrelated building trades or crafts, or to do or superintend the whole or any part thereof.

This does not include anyone who merely furnishes materials or supplies under Section 7045 without fabricating them into, or consuming them in the performance of, the work of the general building contractor.

(b) A general building contractor may take a prime contract or a subcontract for a framing or carpentry project.  However, a general building contractor shall not take a prime contract for any project involving trades other than framing or carpentry unless the prime contract requires at least two unrelated building trades or crafts other than framing or carpentry, or unless the general building contractor holds the appropriate license classification or subcontracts with an appropriately licensed contractor to perform the work.  A general building contractor shall not take a subcontract involving trades other than framing or carpentry, unless the subcontract requires at least two unrelated trades or crafts other than framing or carpentry, or unless the general building contractor holds the appropriate license classification.  The general building contractor shall not count framing or carpentry in calculating the two unrelated trades necessary in order for the general building contractor to be able to take a prime contract or subcontract for a project involving other trades.

(c) A general building contractor shall not contract for any project that includes a fire protection system as provided for in Section 7026.12or 7026.13, or the “C-57” Well Drilling classification as provided for in Section 13750.5 of the Water Code, unless the general building contractor holds the appropriate license classification, or subcontracts with the appropriately licensed contractor.