Garage Door Strut

A garage door strut is a steel channel or formed angle bolted horizontally across the back (inside) face of one or more garage door sections. Its primary purpose is to prevent the section from bowing inward or outward under lateral loads—mainly wind pressure—or under the concentrated force the opener's J-arm applies to the top section during every cycle.

On a standard residential door, a single strut is typically installed across the top section where the J-arm pushes. On wider doors (16 feet and above) or in high-wind regions, additional struts are added to the other sections as well. Manufacturers publish strut schedules—charts that specify the number and gauge of struts required for a given door width and wind-load zone.

Struts are especially important on wider single-car openings and all two-car doors, where the unsupported span is large enough that wind can flex an un-reinforced door section enough to dislodge it from the track. Many local building codes in hurricane or high-wind zones specify minimum strut requirements or require testing to the applicable wind-load standard.

A door section that bows visibly when the wind blows, or that shows a horizontal crease across its face from the J-arm load, typically needs a strut added or its existing strut replaced. Strut installation involves drilling through the section's inner skin and bolting the channel with carriage bolts—a straightforward job that significantly extends door life in exposed locations.