System attachment is the most critical element of roof design and application. Improper attachment results in the increased probability of wind blow-offs and contributes to membrane strain created by differential movement of the system components. The design and application methods must address attachment of the total system and all of the components: substrate, roofing, flashing, metal coverings and penetrations. The most important reason for proper attachment is to prevent damage from wind force, particularly wind uplift.
Wind damage occurs primarily at perimeters and corners and infiltrates the entire system. Generally, wind vortexes occur at the perimeter of the building, displacing perimeter components (flashings, wood nailers, metal coverings, etc.) and creating openings for wind entry. The wind moves through the system in a cross-directional pattern creating uplift and damage at points throughout the system. Wind uplift can also occur from below the deck in facilities that are damaged by wind from interior entry points, such as windows, doors, overhead doors, etc. Secondary wind damage can also occur at the roof from membrane protrusions created by wind-driven projectiles.