If that's the case where you live, ask the contractor for his or her license number, or call the Building Inspection and Licensing Department at City Hall. Confirm insurance credentials. Ask to see proof that the contractor has both liability and workmen's compensation insurance. If the contractor doesn't, you could be liable for any accidents on your property, including injury to the technician. Check into building permits.
Most localities require a building permit for large home improvement projects.
Contact your local licensing or permit department to see if you need one for your project. Make this call before the work begins. Request an estimate. To get an idea of the overall cost, ask for an estimate. Remember, however, that choosing a contractor should be based on more than just the lowest estimate.