A large number of project specifications for low-slope membrane
roof systems designate an Underwriters Laboratories (UL) Inc. Class
A fire-resistance rating and FM Approvals 1-90 wind-resistance
approval. For many buildings' roof systems, these classifications
are in excess of building codes' minimum requirements.
This month, I will explain how specific fire- and
wind-resistance classifications are determined.
Roof assemblies' resistances to exterior fire exposure are
tested and classified using two similar test methods: ASTM E108,
"Standard Test Methods for Fire Tests of Roof Coverings," and UL
790, "Tests for Fire Resistance of Roof Covering Materials." These
tests provide the basis for the "Class A," "Class B" and...
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