Torsion vs Extension Garage Door Springs: How to Tell Them Apart and Which Is Safer

Look above the door with it closed. A torsion system is a steel shaft running across the top of the opening with one or two tightly wound springs on it, cable drums at each end, and cables running down to the bottom corners of the door. On a Wayne Dalton TorqueMaster door the springs are inside the tube and you'll see only the tube; on a Clopay or Ideal EZ-Set door there are winding units at the ends of the shaft.

An extension system has no shaft. Instead, a long spring runs beside each horizontal track, parallel to the ceiling, with a pulley at the end and a cable that runs over it down to the door. When the door closes, the springs stretch; when it opens, they contract and pull. Extension doors are common on older Winnipeg houses and on single doors, and they need about 10 inches of headroom against 12 for standard torsion.

A torsion spring stores energy by twisting. It drives the door from a central shaft through the drums, so both cables are pulled by the same shaft and the door rises level. The spring is also fixed to the shaft, which means that when it breaks it breaks in place: a bang, a gap in the coil, and a door that's suddenly heavy, but nothing flies.

An extension spring stores energy by stretching, and each side works on its own. Because the two sides aren't tied together, the door can lift unevenly, and Garaga notes the springs stretch and contract more with every use. When an extension spring breaks it's a stretched steel coil letting go, and without containment the broken end can travel across the garage. That's why the industry body DASMA tells inspectors to check that every extension spring has a safety cable running through its centre, anchored at both ends: the cable catches the pieces.

Torsion, where the headroom allows it, and standard torsion hardware needs about 12 inches of clear space above the door, a bit more with an opener. Low-headroom torsion kits work down to around 5 inches. Our position on the spring repair page is that when an extension spring breaks, the two safer routes are a proper containment cable through each spring, or converting the door to torsion. We quote both and recommend the conversion on most doors, because it also sorts out the uneven lift and the pulley wear.

If your extension springs are fine and you're not changing them, the one thing to check today is the safety cable. No cable through the spring is a call for an inspection, whichever company you use.

Standard residential springs of either type are rated around 10,000 cycles, an open and a close being one cycle, which works out to roughly seven years at average use and less for a busy door. Garaga offers higher-cycle springs, 20,000 to 25,000 cycles, that roughly double that. Rust, a spring sized for the wrong door weight, and a door that's out of balance all shorten the count, and a Winnipeg winter is hard on all three.

On a two-spring door we replace both when one breaks, which is DASMA's guidance as well as ours. They were installed together and have done the same cycles, so the survivor is close behind, and a mismatched pair leaves the door out of balance. Spring replacement, winding, and tension adjustment are not homeowner jobs on either system; the balance test is as far as a homeowner should go.