NRCA has received a significant number of complaints from
contractors stating manufacturers claim a relationship between
improper fastener placement and asphalt shingle failures. As a
result, NRCA conducted a limited study of architectural, laminated
asphalt shingles commonly used in the U.S. roofing industry. One of
the study's purposes was to provide some background data for use by
NRCA in developing appropriate nail placement tolerances for such
Asphalt shingles enjoy widespread acceptance in the U.S. roofing
industry. During the past several years, architectural, laminated
asphalt shingle use has surpassed the use of conventional three-tab
strip shingles and now is more than half of all asphalt shingle
In 1998, NRCA began looking into application tolerance
guidelines for three-tab strip shingles. This investigation spurred
from reports by NRCA-contractor members that several manufacturers
were claiming improper fastener placement during application was a
reason for failures in specific asphalt shingle roof assemblies.
(For additional information regarding fastener placement
tolerances, see "Asphalt shingle application tolerances,"
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