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Impact Resistance of Prepared Roof Covering Materials

UL 2218

1 Scope

1.1 This test method provides impact resistance data for the evaluation of prepared roof covering materials. For purposes of this Standard prepared roof covering materials are considered to be small units, sheets or panels designed for installation with multiple layers of such materials installed in overlapping rows normally on inclines exceeding 25 percent.

1.2 The test evaluates the effect of impact from the steel ball at locations on the assembly selected to be most vulnerable, such as (but not limited to) edges, corners, unsupported sections and joints.

1.3 This test method does not evaluate the effect of weathering, temperature, aging or similar effects on the impact resistance of prepared roof covering materials. These and other factors, including time, roof slope, roof system configuration and application influence the performance of roofing materials in the field. It is not the objective of this test to address all of these factors.

1.4 The impact energies used in this Standard were derived from impact energies of actual hailstones (see Appendix a). However, largely due to the effects discussed in 1.3, there is no currently established direct correlation between the performance of roof covering materials when impacted by hailstones versus steel balls. Consequently, this test method does not provide a direct basis to compare expected performance under all hail conditions, but does provide a basis for comparison of the response of roof coverings when subjected to the impact energies described herein.