Sep 01, 2006 · Because FM Approvals requires a 2:1 safety factor, roofs with field of roof uplift forces of 30 pounds per square foot are the maximum for 1-60 ratings, and 37.5 pounds per square foot are the maximum for 1-75 ratings, etc. In this scenario, our building, which is designed with 23 pounds per square foot of uplift, would require an FM Approved
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