A roofing contractor installs products and repairs surfaces that seal, waterproof and weatherproof structures. This work is performed to prevent water or its derivatives, compounds or solids from penetrating such protection and gaining access to material or space beyond. In the course of this work, the contractor examines and/or prepares surfaces and uses the following material: asphaltum, pitch, tar, felt, glass fabric, urethane foam, metal roofing systems, flax, shakes, shingles, roof tile, slate or any other roofing, waterproofing, weatherproofing or membrane material(s) or a combination thereof.