Do not take out a building permit for the contractor. When the contractor signs the permit application, they are agreeing to do the work according to code. If you apply for and sign the permit application, you are liable for correcting the contractor's work if it should fall short of City or State building code standards. Make sure your contractor has a permit and that the contractor calls for inspections. An inspection card will be issued and should be displayed near the work area.
When each inspection has been completed, the City's Inspector will sign the card. When the final inspection is approved, the inspectors' signatures are your assurance that the work has been properly inspected and no violations of the building code were discovered. You should pay for the work only after it has passed final inspection.