Although it may seem like an extremely large job, finding out information on roof replacement is easier than the actual job. You should be looking for a company that comes highly recommended for their prices, their professionalism and their work. Consult with your family or friends to see if they can recommend someone to you. If not, there are plenty of advertisements in the phone book and on the Internet. The Internet is also a good way to find out information about costs, materials and a place to obtain references, if the company you are looking into has a website. Everything that is needed for the replacement, from new shingles to trash removal, should be covered in a written estimate so that you are able to compare prices.
Any company that specializes in residential and has some years of experience in the business should be able to give a proper estimate on the cost. They can take a look at the work you need done and explain to you what makes the difference in costs. If you have to replace the entire roof, it is up to you whether or not you tear off the old one or nail shingles on over the old one. The latter is not recommended but is a common practice because tearing off the old roof can add to the resulting price. It is a good idea to tear off what was previously there to avoid problems in the future but because it costs more to do so, most homeowners will opt for the cheaper price.
Tearing off an old roof creates a great deal of mess from the old shingles and nails. The clean up and removal of this mess requires more time and crew members. This is why the price is understandably higher than a nail-over method. A homeowner can rent a dumpster if they so choose but most professional roofing companies will take care of this on their own, with their own methods of trash removal. It will be reflected in the estimate.
The warranty on the new roof should be standard for new shingles. This is between 20 and 30 years. The company that installs the roof will most often offer a similar guarantee on their work. If they have a good reputation for being dependable and for doing good work, you should not need to worry about it. It is best if all crew members are highly qualified, skilled and professional. If they need to be certified for their position, they should be. The company should also be insured to protect the safety of the crew and the residents of the house.