If your commercial overhead door stops halfway or reverses when trying to close, a bent or broken strut is a common mechanical cause. Struts are rigid steel arms mounted vertically on the door panels to prevent flexing during operation. When a strut is damaged, it can bind in the tracks or interfere with the door’s alignment, triggering safety sensors or causing the motor to stall. You’ll often hear a scraping or grinding noise at the same point in the travel, or see the door jerk before stopping. This issue is especially common in wide doors over 14 feet where wind load and panel deflection are greater.
How Struts Support Door Movement
Struts run from the top hinge to the bottom bracket on each section, keeping the door rigid as it rolls along the tracks. Without them, wide panels would bow under their own weight or wind pressure, causing rollers to jump the track or bind. In steel doors, struts are typically 11- or 14-gauge galvanized steel, either continuous or segmented. Aluminum doors use extruded struts for corrosion resistance. Their job is purely structural—they don’t move, but they must remain perfectly straight and aligned for the door to travel smoothly.
Signs of a Failing or Damaged Strut
A damaged strut often shows visible bending, kinking, or twisting when inspected. You might notice the door rubbing against the track on one side, or see uneven gaps between the door and jamb. Operationally, the door may close partially then reverse, mimicking a sensor fault. Listen for a rhythmic squeak or grind that occurs at the same point each cycle—this indicates the strut is catching on a track bolt or roller bracket. If the door sags in the middle when open, that’s another sign the struts aren’t providing adequate support.
What Causes Strut Failure
Struts fail from impact—forklifts, pallets, or vehicles bumping the door—or from long-term fatigue due to constant flexing. In coastal areas like Metro Vancouver, salt air accelerates corrosion, weakening the steel over time. Improper installation, such as over-tightening bolts or using the wrong fasteners, can create stress points that lead to cracking. Doors in high-cycle facilities (over 25 cycles/day) see more wear. Rarely, manufacturing defects in the steel or welds can cause premature failure, but external damage is far more frequent.
What You Can Safely Check Yourself
Before calling a technician, inspect the door with it fully open and locked out. Look along each strut for visible damage—dents, bends, or rust that compromises the steel. Check that all mounting bolts are snug but not over-torqued; loose bolts let the strut shift, while over-tightening can deform the track angle. Spin the rollers by hand to ensure they’re not seized or wobbling. If the door binds manually at a specific point, trace that spot to see if a strut is contacting the track or a bolt head. Never attempt to straighten a bent strut—it’s tempered steel and will likely crack if forced.
When This Is Not a DIY Repair
Replacing a strut requires removing the door section from the tracks, which means lowering the door safely and supporting its weight. This involves working under a suspended load and dealing with torsion spring tension if the door is equipped with them—even if you’re not touching the springs, releasing the door from the opener puts it under full spring force. Strut replacement also demands precise re-alignment of the section to maintain even reveal and smooth roller travel. Misalignment here causes premature roller wear or track damage. For these reasons, strut replacement is a technician job.
Frequently Asked Questions
### Can a door operate with one missing strut?
No. Operating with a missing or broken strut risks panel buckling, roller failure, or the door coming off the track. The door may seem to work initially, but under load or wind, the unsupported section will flex, creating a safety hazard and accelerating wear on other components.
How much does strut replacement typically involve?
It depends on door size and strut type, but the process usually takes 1–2 hours per strut for a technician, including disassembly, part replacement, re-alignment, and operational testing. Accessibility and ceiling height affect time—high-lift or vertical-lift doors take longer due to additional rigging.
Are there preventative measures for strut damage?
Yes. Install impact-resistant strut guards in high-traffic zones, and schedule quarterly visual inspections as part of your preventive maintenance plan. Keep the tracks clean and lubricate rollers and hinges—while struts don’t need lubrication, reducing friction elsewhere minimizes the forces transmitted to the struts themselves.
