What Is a Wind Uplift Rating for Roofing?
Wind uplift ratings classify the roof assembly's resistance to the wind's suction — the FM Approvals 1-60/1-90 (the 60/90 psf) or the UL 580 (the Class 30/60/90) — the assembly tested as the system (the deck, the insulation, the membrane, the fastening). The rating must meet or exceed the ASCE 7 components-and-cladding pressures at the roof's zones (the corners' — the highest). The specification: the rated assembly, not the rated membrane.
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The rating systems
FM (the 1-60, 1-90, 1-120 — the psf; the insurer's — the approval), UL 580 (the Class 30/60/90 — the uplift; the test), and the Miami-Dade (the NOA — the hurricane's; the product approval). The assembly (the tested — the substitution's prohibition).
Design pressures
ASCE 7 (the C&C — the zones; the corners, the edges, the field; the parapets' — the effect), the comparison (the rating vs. the pressure — the assembly's adequacy), and the enhanced (the hurricane — the higher; the edge metal — the ANSI/SPRI ES-1).
Construction and warranty
The fastening (the pattern — the tested; the corners' — the enhanced), the inspection (the FM's — the approval's; the manufacturer's — the warranty's), and the maintenance (the warranty's — the 20-year; the inspections). The uplift rating is the roof's wind design — the assembly tested, the patterns followed.
The bottom line
Specify roof assemblies by wind uplift rating (FM 1-60/1-90, UL 580) meeting ASCE 7 corner/edge/field pressures — install to the tested fastening pattern; verify edge metal per ANSI/SPRI ES-1.
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