Wind Uplift Testing of Metal Roofs

Wind blowing over a roof creates suction that tries to lift panels, especially at corners, edges and ridges. Because metal panels are attached at discrete points (clips or screws) rather than continuously, the design of those connections and their spacing is critical. Engineered metal roof systems are therefore tested as complete assemblies.

Common test methods

• ASTM E1592: a structural test of sheet metal roof panel assemblies under uniform static air pressure.
• UL 580: a standard test for uplift resistance of roof assemblies.
• UL 1897: another uplift test for roof assemblies.
• Regional approvals: hurricane regions such as Miami-Dade County, Florida, have their own product approval and test requirements, and some products are tested for high-velocity hurricane zones.

Design factors

• Engineering calculations, often based on ASCE 7 in the United States, set design pressures for each roof zone.
• Clip and fastener spacing is reduced at corners and perimeters, where uplift forces are highest.
• Locking seams that engage clips firmly ("active fastening") help panels pass uplift tests; mechanically seamed double-lock panels typically achieve higher values than unseamed snap-lock panels.
• Substrate type and fastener pull-out strength matter as much as the panel itself.

Real-world performance

Industry reviews of hurricane and tornado damage report that properly engineered and installed metal roofs perform well, while failures usually trace to inadequate attachment at edges, missing clips, weak decks or fasteners driven into poor substrates.

Using ratings

A rating applies only to the specific tested assembly, including panel, gauge, clip, fastener, spacing and deck. Specifiers should match project details to the tested configuration, and some specifications require wind uplift ratings to meet the local building code.