Problem & safety
Broken Commercial Door Spring: Why You Must Not DIY
A door spring stores an enormous amount of energy so a motor or a person can move a door that weighs hundreds of pounds. When one breaks, the door becomes dangerous — and so does the spring itself. This is the one repair the whole industry agrees an untrained person should never attempt.
What's happening
Overhead doors are counterbalanced by springs — usually a torsion spring on a shaft above the door, sometimes extension springs along the tracks. The spring does the heavy lifting so the opener (or a person) only has to overcome the difference. When a spring breaks, that counterbalance is gone and the full weight of the door drops onto the cables, the opener, and whatever is holding it.
Signs of a broken spring:
- A loud bang from the door area, often heard before anyone noticed the door was stuck.
- A visible gap in the torsion spring above the door — it looks like two pieces where there was one coil.
- The door suddenly feels extremely heavy, or the opener strains, hums, and won't lift it.
- The door came down fast or crooked, and may now also be off track.
- A slack or hanging cable on one side.
Stop using the door now
A door with a broken spring is not a "use it carefully" situation:
- Don't run the opener — it can pull the door crooked, snap a cable, or damage itself.
- Don't try to lift the door by hand; without the counterbalance it can drop and crush.
- Keep people and vehicles from under and beside the door.
- If the door is stuck open, secure the opening another way — see below.
Why spring work is a trained-technician-only job
DASMA, the door industry's technical association, states it directly: replacing garage door springs "should only be performed by a trained door systems technician." A torsion spring and the winding bars used to service it are under extreme tension; a slip can cause severe lacerations, broken bones, or fatal injury. There is no safe way for an untrained person to unwind, replace, or "just look at" a spring under load — which is why this site will never publish DIY spring instructions. It is not gatekeeping; it's the documented reason people are seriously hurt every year.
Safe temporary measures
- Leave the door where it is and cordon off the opening on both sides.
- Red-tag the opener control: "OUT OF SERVICE — BROKEN SPRING — DO NOT OPERATE."
- If the building is open to the outside, protect the opening without moving the door — see securing your building after hours.
- Take a photo of the spring assembly from a safe distance for the request.
What speeds up the repair
A good photo of the spring shaft and hardware often lets a contractor arrive with the right spring, which avoids a second trip. Helpful details:
- A photo of the torsion shaft and springs above the door, and the cables and drums at each end.
- Roughly the door size and number of panels, and whether it's insulated.
- Whether it's a busy, high-cycle door — that affects the spring a contractor will recommend.
- Whether the door is stuck open (a security issue) or closed.
On a frequently used door, technicians often replace springs in a matched pair so the second one doesn't fail a few weeks later. Ask for a written estimate that separates parts and labor — our contractor guide explains why that matters for spring jobs in particular.
References
- DASMA — garage door safety: spring replacement by trained technicians only — www.dasma.com/safety-tips/garage-doors
- DASMA — torsion spring hazard information — www.dasma.com/torsion-spring-terrorism