If you have to ask this question, you should not try to contract a job yourself. Knowing what is needed from a contractor is what seperates the novice from the profesional. I have supervised jobs that had profesionals bid the job, but never read the returned subcontractor bid. The omissions tripled the cost of construction. Almost every contractor could read the situation and do as he liked. Even on the simple clean-up of the finished construction, the subs can smell ignorance. Construction is not difficult as long as you dot all Is and cross all Ts. The problem is most are not skilled to do this task properly.