A professional commercial roofing contractor will generally provide a range of choices for the roof but there are some that specialize in a certain type of roofing like shingles or metal roofing.
Make sure that you check with the contractor if they specialize or have much range of choices so you can get the desired finish and look of the commercial building that you want. If you would need a specific type of roofing make sure to ask the commercial roofing contractor about their experience in putting on that particular type of roofing.
Ask to see examples and pictures of previous jobs that have similar requirements as you have. If it is possible you can call previous customers to see how their roofing experience went with the contractor.
Most will have a website that you can visit so you should look at their customer reviews as these can be very important when deciding which commercial roofing contractor you are going to hire. You can also check with the Better Business Bureau to see if there are registered complaints against them.
If you are concerned with environmental issues, look for a green roofing commercial roofing contractor. These are the businesses that specialize in using environmentally safe installation procedures and sustainably sourced materials.
Make sure that you ask the contractor exactly what makes them environmentally conscious because saying they are a “green roofing contractor” could just be an advertising gimmick to get new customers.