Torsion or extension: which one is on your door
Look at the wall above the closed door. A torsion door has a steel shaft running across the width of the door, with one or two tightly wound springs on it and a cable drum at each end. The springs twist as the door closes and turn the shaft to lift it.
An extension door has no shaft. Its springs run alongside the horizontal tracks above your head and stretch as the door closes. Each one should have a safety cable running through its middle, so a spring that snaps stays on the cable instead of flying loose.
In our job records, 12 of the 13 spring repairs with a recorded type were on extension springs, and all seven new-door jobs went in with torsion springs.
What wears a spring out
Springs are rated in cycles: one cycle is the door opening and closing once. How many cycles a spring actually lasts depends on how it was handled, installed and used.
DASMA, the door and opener manufacturers' association, lists what shortens that life after a spring leaves the factory: rust, which thins the wire and weakens it; a spring that does not match the door's weight; weight added to the door later, paint included; a door left open for long stretches in heat, cold or wet weather; and springs that are not lubricated as the door maker's instructions say.
High-cycle springs are rated for more cycles than standard ones. One of the 13 spring repairs in our records used high-cycle springs: Chelmsford, June 2026.
Source: DASMA Technical Data Sheet 190, Factors Affecting Spring Cycle Life (PDF)
