A.Architect and roofing consultant Harrison McCampbell responds: Asphalt shingles should always be installed according to the manufacturer’s instructions, which are usually printed on the shingle wrapper. Because the thickness, weight, and shape of shingles vary, manufacturer’s instructions vary slightly. But virtually all manufacturers agree that nails should be installed below the adhesive strip. To keep a warranty intact, follow the manufacturer’s nailing and installation instructions closely. If you deviate, whether you think it is a better installation or not, be prepared to roll with the directive from the manufacturer if there is a leak or performance question.
If you nail too low, nail heads can be exposed, with the potential for water entry. If you nail within the adhesive strip, the nail head cuts down on the amount of asphalt surface available to hold the shingle down.
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