Roofing: it's what undercover that counts
March 12, 2018
Modern roof coverings—from asphalt to metal—all perform well, but it is what is underneath the shingles that often dictates long-term performance.
Renovation contractors replacing roofs should therefore steer their homeowner clients to the best quality of underlayment they can afford. This will add to the life of the roof and reduce callbacks due to leaks.
Generally, the ratings of good, better, or best, begin with basic rolled underlay material. This material is usually asphalt-saturated felt paper, rated as No. 15 weight, and rises to the better choice of felt that is reinforced with fibreglass, a No. 30 weight paper.
Most professional roofing contracts will recommend No. 30 paper, though it weighs up to 20 pounds per square (100 square feet).
The best material, however, is new synthetic underlayment. It can cost up to three times more than conventional No. 15 or No. 30 paper, but provides superior moisture resistance, is lighter than No. 30 paper, more resistant to tears, and provides a degree of insulation. Major suppliers like OwnCorning and GAF offer the synthetic underlayment, but there is a wide choice from other suppliers.
The trick is, though, that all the value is in the material. Since these polymers are easier to install and skid-resistant, your labour costs could actually be lower. But your homeowner client will likely be happier with the long-term result, which could mean a valuable referral.