The first phase of IBHS research into
wind resistance of asphalt shingle
products has produced a number of
clear takeaways. It also is providing
direction for the next phase of research as IBHS seeks to improve wind
resistance and ensure enhanced performance throughout the shingle’s
life expectancy. Phase I has focused
on three tab shingles because they
are widely represented in the marketplace, and existing test methods
and rating systems are fairly simple.
Researchers have explored a number
of issues with these products, since it
is possible to focus on the relatively
small area of a single exposed shingle
tab as opposed to the entire exposed
length of an architectural shingle.
Two test methods are currently being used to rate the wind resistance
of asphalt shingle products. The older
one is ASTM D 3161, and the newer
one that is replacing ASTM D 3161 in
the International Building Code and
International Residential
Code is ASTM
D 7158. ASTM D 3161
is a pass/fail test that
involves blowing wind
over an inclined deck
(2 on 12 slope) covered
with shingles for a period of two hours. This
setup is shown in Figure
1. This test is essentially
a long-duration evaluation of the uplift resistance of the shingle
seal strip after sealing
under minimal heating
conditions.
Figure 2. ASTM D 7158 Test Setup using IBHS’ COMET
(Component Materials Evaluation Testing) Apparatus
An ASTM D 7158 rating is achieved
through a combination of tests. The
first test involves determining an appropriate uplift coefficient that can
be used to calculate a wind uplift
load for any desired wind speed. The
wind portion of the test is conducted with the same basic apparatus as
the ASTM D 3161 test except that the
slope of the specimen is reduced to
produce a skimming flow (Figure 2)
and a turbulence grid is installed at
the outlet of the jet of wind. This is
paired with tests that determine the
resistance of the shingle sealing strip
to uplift for the purpose of calculating a wind speed necessary to overcome that resistance. The resistance
is determined using a universal testing machine that pulls the connection apart in a relatively short time
(minutes) as opposed to applying the
wind load for hours in ASTM D 3161.
An ”H” rated shingle product, which
FIGURE 1 (full-page): ASTM D 3161 Test Setup using IBHS’
COMET (Component Materials Evaluation Testing) Apparatus
Disaster Safety Review | 2013
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