Concerned about the condition of your New York-area home's roof? Angie's List asked the roofing contractors at highly rated Prime Home Improvement in White Plains, N.Y., about what every homeowner should know about their roof.

"All homeowners should be aware of a number of points regarding their roof," says company vice president Gino Ciuffetelli.

How old is the roof?

"Roofs with the older three-tab shingles have a life expectancy of about 15 to 20 years. Roofs with older architectural shingles will last approximately 20 to 25 years," Ciuffetelli says. "All the new architectural laminate roof shingles have a lifetime warranty and should last from 35 to 50 years."

Does the roof have more than one layer of shingles installed?

"In past years, up to three layers of roofing were permitted in New York metro area," he explains. "But the building code has been modified to accommodate excessive snow, ice and wind load factors. There's now a maximum of two layers of roofing permitted in new installations on homes in New York state."

Is there adequate ventilation for the size of your roof?

"Not having adequate ventilation on your roof can have serious effects," Ciuffetelli says. "Without the right ventilation, overheating in high temperatures will dry the roof shingles and may cause them to delaminate, become brittle or be blown off by strong winds during storms."

Who installed the roof and are there any warranties remaining on it?

"You should always keep all your roof warranty documents in an easy-to-find place," he advises. When hiring a roofing contractor, Ciuffetelli says a company's longevity is just as important as its expertise. "Be sure that your roofer is a qualified professional," he says.

"Unlike installing kitchen cabinets or drywall, most consumers don't go onto their roof to check on it while it is being installed. But you also want to find someone with a track record that shows they'll be in business years down the road when you may need them.

"If you don't know the answers of any of the above questions, have an inspection of the roof done by a reputable contractor to determine the condition," Ciuffetelli says. "Many roofing contractors provide this service at no charge."