There are certain qualifications that an exterior contractor should have before you even consider them. First, that they are a legitimate business as registered with the state of Tennessee. Second, any professional stepping foot on your property should be covered by the proper General Liability and Workers Compensation Insurance. General Liability insurance protects the contractor, and subsequently you, from the financial consequences that a disaster might bring.  Workers Compensation insurance protects an employee in the case of an injury, and is required by law for any entity with more than 1 employee.  Any company that does not have the foresight to follow these standards should not be doing work for you, especially not on your home.  Your contractor should be able to provide a Certificate of Insurance proving coverage of both with two business days notice.