Selling roofing services can be extremely difficult and isn't for the faint of heart. Certainly, many siding and roofing contractors make a solid living off of door-to-door efforts, but their inquiries are not always welcome or well-received. It can make life a lot easier if your salespeople have a blend of outbound, and inbound inquiries (from things like Thumbtack, Google Local Services, PPC, and Search Engine Optimization.) If you do have leads to provide to your salespeople it can allow them to not burn out so quickly, and keep their energy high. You don't want them to only be dependent on leads the company gives, however, as a roofing contractor I'm friends with says – "They'll turn into 'lead babies.'" Provide leads, but make sure they hunt for themselves as well.