If something happens on your property you do not want to be first litigated against if a lawsuit occurs. A commercial roofing contractor should be paying lots of money for insurance protection to make sure that does not happen. Insurance premiums are one of the reasons why commercial roofing costs so much. The contractor should have general liability, workman’s comprehensive, employers liability, automobile and umbrella coverage. You can ask for an insurance certificate to verify coverage with the proposal. You should demand an insurance certificate with the legal entities involved named on it before work starts. If you have questions check with your insurance agent.