Having your roof redone or building a new house? So you must be looking for a company that executes roof works! Most countries have some kind of matching site that can match your work to the right contractor, like this example from Belgium: ik zoek een vakman (litteral translation: looking for a professional).
Roof works: find the right contractor
It's not always easy to find the right professional for your work. However, in most countries local websites are available where independent professionals and clients can meet.
All you have to do is put a little ad online (which generally doesn't commit you to anything). Professionals also roam these sites, and they can send quotes to the people who posted their work on the website.
As a client, all you have to do is review the quotes you receive and choose the professional you would like to work with.
These kinds of sites are very useful as they bring people together so you can find the right match for your work.