Asphalt shingles are the most popular
residential roofing material on the
market, and for good reason: They’re
cost effective, adaptable to a wide variety
of roof forms, and come in an array of styles
and colors to suit almost everyone. But while
most builders have spent their share of time
nailing off shingles, there’s no shortage of unanswered
questions on the subject. How do 20-year
shingles differ from 25-year shingles? Why is felt
underlayment required in fire-rated roof assemblies?
What’s the most leakproof valley detail?
To fill in some of the blanks, we put those
questions and others to a half-dozen industry
experts: Carl Cash, a former chair of the ASTM D-
08 committee on