The California Contractors State License law requires contractors to display their license number prominently along with all advertising. It's a good idea to check it with the Contractors State License Board, for the following: Date issued, Insurance, employees, Disciplinary actions, etc... A very important bit of data is how long they've been in business under that particular license number. No excuses should be accepted like "we were in business under another number before". The current License number is the only one relevant to you, because that is the number and business you are dealing with currently.
Contractors licenses are issued based on different classes, defined alphanumerically.
License Class C39 / Roofing, gives a contractor the privilege to perform roofing services only. He may not perform other services for which he is not licensed for such as Carpentry with the following exceptions: a) He also carries a framers or general contractors license. (Class B or C5) b) He hires or subs out to the properly licensed contractor. (Class B or C5) c) The woodwork is a minor part of a larger roofing project.
License B/ General / “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 with the following exceptions:
a) The prime contract requires at least two unrelated building trades or crafts other than framing or carpentry.
b) or unless the general building contractor holds the appropriate license classification or subcontracts with an appropriately licensed specialty contractor to perform the work.
A general building contractor shall not take a subcontract involving trades other than framing or carpentry.
a) unless the subcontract requires at least two unrelated trades or crafts other than framing or carpentry.
b) or unless the general building contractor holds the appropriate license classification.
The general building contractor may 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.” (CSLB).
License Class C5 / Framing and Rough Carpentry Contractor / A framing and rough carpentry contractor performs any form work, framing or rough carpentry necessary to construct framed structures; installs or repairs individual components of framing systems and performs any rough carpentry or associated work, including but not limited to the construction or installation of: sub-flooring, siding, exterior staircases and railings, overhead doors, roof decking, truss members, and sheathing.