Check with the BBB to verify a contractors credentials and how long he has been in business. This synthetic layer, which replaces felt paper, covers the entire roof deck and is the second line of defense against leaks, after the shingles. Ultimately my answer is yes you can repair or replace your own roof, but I would rarely suggest that you actually try it. All that being said, choose a contractor carefully and do a little research, don’t hire the first guy that pulls up in a pickup truck with a hammer.
Most won’t cover roof repairs and replacements due to normal aging and wear-and-tear, but many will cover roofing damage caused by common perils, such as hail, fire, or winds.