Garage door spring cycle ratings explained

Count honestly. Most people underestimate: each departure and return is one cycle, so two cars leaving and returning on a weekday is four cycles, not two. Add school runs, deliveries and the bin.

At 2 cycles a day a 10,000-cycle spring lasts about 13 years. At 4 a day, about 7. At 8 a day, about 3.5. At 12 a day — a large household using the garage as the front door — about 2.3.

That last figure is why springs seem to fail early in busy houses. They are not defective; they are correctly rated and being used four times harder than the rating assumes.

Upgrading from 10,000 to 25,000 cycles typically adds $80 to $150 to a spring replacement and multiplies the expected life by roughly 2.5.

It pays whenever your calculated life is under about six years, because you are otherwise buying a second call-out — the labor, the trip charge and the disruption — inside the period the upgrade would have covered.

It does not pay on a door cycled twice a day. A 13-year standard spring already outlasts most people's ownership of the house.

An unbalanced door. If the counterbalance is out, the spring is working against a load it was not sized for on every cycle. This is what a tune-up's balance test catches.

Freeze–thaw cycling, which fatigues the steel independently of use. A spring in a 60-cycle-a-year climate reaches its fatigue limit sooner than the same spring in a desert.

Corrosion, which raises inter-coil friction. Galvanised springs cost about 10 percent more and are the correct choice within a few miles of salt water.

Undersizing. A spring wound to the wrong wire diameter or length for the door weight will hit its limit early regardless of its nominal rating — which is why a suspiciously cheap replacement is often a rating problem rather than a bargain.