There are three important spring measurements that you will need to take. These measurements must to be accurate, or the door may not function properly.

Each time an extension spring expand and contract, it loses some of its strength. They usually last about 5 – 10 years, depending on how often your door goes up and down in a day. Also the weight of your door will determine spring life.

Determining what spring you need is typically easy if you have Holmes springs. You will see a spring tag on each of your springs. The easiest way to find a substitute spring is to get a replacement spring with the same tag.

It is very seldom that you do not find a spring tag that does not have a spring size on it. The most common spring size for a one piece door is 728C. Sometimes the door requires 2 springs and heavier doors can require 4 springs.

Replacing these kinds of springs is pretty straightforward, so you have to replace with equal springs as the broken ones. Being very careful is key to keep from injuring yourself.