Roof shingles are rated for impact resistance.
Primary concern: hail
Testing protocol: UL 2218
Testing Conditions: steel ball dropped from 20 feet perpendicular to the shingle surface
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Ability to Withstand a Steel Ball Without Cracking
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Class
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1.25 inches
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1
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1.5 inches
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2
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1.75 inches
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3
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2.00 inches
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4
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The ability to withstand impacts decreases with age and environmental conditions.
Benefits of superior impact resistance:
(1) longer life-expectancy
(2) insurance discounts
(3) greater resistance to other environmental conditions such as winds
