When checking references for a roofing contractor, be sure to ask if the contractor showed up for work on time and finished the project in a timely manner. Also ask if the roofing contractor was economical with material use and if he kept the work site clean and free of hazardous debris.
Choosing the lowest bid from a roofing contractor is not always the best avenue to take. In addition to pricing, take into account reference checks you have done, licensing and registration requirements, as well as your own feelings about whether or not the contractor will work within the guidelines that you set.