In many U.S. regions, the ability of roofing products to resist
hail damage is an important performance consideration. Currently,
two test methods—UL 2218 and FM 4473—are frequently
used to assess products' impact resistances. However, limitations
in these test methods may preclude the tests from accurately
measuring products' hail-resistance performance.
UL 2218, "Standard for Impact Resistance of Prepared Roof
Covering Materials," provides for impact-resistance data for the
evaluation of prepared roof covering products. Examples of prepared
roof covering products include asphalt, wood, tile, fiber-cement,
plastic and metal shingles.
With this standard's test method, a 3- by 3-foot specimen of
newly manufactured (nonweathered) roof covering is subjected to
impacts from steel balls of varying sizes dropped from specific
heights at standard laboratory conditions. The masses of the steel
balls combined with the drop heights are said to represent...
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