A roofer can offer roofing services related to roofing work, such as a maintenance or inspection program. When they put them on your roof, they usually do the work on gutters, side boards, or metal flanges, or hangers, or spotlights.
If you have a metal roof on a commercial building, they offer roofing services such as material resurfacing or perhaps UV coating or painting. This person can be called a roofing professional who happens to have some extra clapboard in the truck.
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So they can come and replace the tiles that blew off your roof in a windy storm last night. This service must be performed immediately or you will have to go to the next apartment.
By the way, you want to be paid cash. And no, they won't have any real references, but they can get you on a few calls with people who are on call and also engage in scams who are happy to tell you how great this roofer is.
This roofer is unlicensed and it is a limited time or one time offer just for you. They often turn to parents who can't get out to see if their roof really needs repair. The price may be cheap, but the workmanship is also cheap. This new shingles can be lifted off the roof in the next light breeze.