A garage door is the heaviest moving object in a normal house, and almost all of its weight is held by springs under enormous tension. That single fact decides which parts of this you can sensibly investigate and which you cannot.
Never touch the springs. The torsion spring above the door, and extension springs along the tracks, store enough energy to cause severe injury or worse if they release. This is not general caution — spring replacement is the one common home repair with a genuine record of killing people. It is a job for somebody with the right winding bars and the experience to use them.
Check these four first
- The safety sensors. Two small units near the floor at each side. If one is knocked out of alignment, blocked by a bin or a leaf, or has a dirty lens, the door will refuse to close — usually with a blinking light on the opener. This is the single most common cause and the fix is often wiping a lens and nudging a bracket.
- Power. The opener unplugged, a tripped breaker, or a GFCI outlet that needs resetting. Worth ruling out before anything else because it costs nothing.
- The remote and the wall button. If the wall button works and the remote does not, it is a battery or a reprogram, not a door. If neither works, the problem is the opener or the power.
- The manual release. A red cord hanging from the trolley. Pulling it disconnects the door from the opener so you can lift it by hand — which is also a diagnostic (see below).
The test that tells you what is wrong
With the door fully closed, pull the red release cord and try to lift the door by hand.
- It lifts fairly easily and stays put halfway. The door and springs are fine. The problem is the opener, the sensors or the power.
- It is extremely heavy, or slams back down. A spring has broken. Stop. Do not put your car under it and do not use the opener — running an opener against a broken spring destroys the opener as well.
- It binds, scrapes, or moves unevenly. A track, roller or cable problem. Also not a DIY job once cables are involved, because cables are under the same tension as the springs.
Do the release with the door closed, not open. Releasing a partially open door with a broken spring drops it.
Getting the car out
If a spring has gone and the car is inside, it is worth waiting for somebody rather than improvising. If you must, it takes two people, and the door has to be blocked open with something solid — locking pliers clamped to the track below a roller on each side. Never put any part of yourself under a door held up only by hands.
What a repair usually involves
Springs are replaced in pairs even when one broke, because the second is the same age and will follow within months, and a second call-out costs more than the part. Cables and rollers are usually done at the same time for the same reason. Openers are frequently more sensible to replace than repair once they are over about fifteen years old, particularly if the model predates rolling-code security.
Who to call
- Springs, cables, tracks: a garage door specialist. Not a general handyman, and not you. This is the clearest line in home repair.
- Opener replacement: either. Swapping a functioning-door opener is within the range of a competent local, and a lot cheaper.
- Sensors, brackets, lubrication, weather seal: a local, or you. Ordinary maintenance.
We do not verify anyone's licence or experience, so on the spring work in particular, ask directly how long they have been doing it and check the company independently before anybody starts.
Frequently asked questions
Why will my garage door not close?
Most often the safety sensors near the floor are misaligned, blocked or dirty — usually shown by a blinking light on the opener. Check that both are pointing at each other, that nothing is in the way, and that the lenses are clean. That single cause accounts for a large share of these.
How do I know if a garage door spring is broken?
With the door fully closed, pull the red manual release cord and try to lift it by hand. If it is extremely heavy or slams back down, a spring has gone. If it lifts reasonably and stays put halfway, the door is fine and the problem is the opener, sensors or power. Do not use the opener with a broken spring — it destroys the opener too.
Can I replace a garage door spring myself?
No. Torsion and extension springs store enough energy to cause severe or fatal injury, and this is the one common home repair with a real record of killing people. It needs proper winding bars and experience. Cables are under the same tension and belong in the same category.
Should I repair or replace a garage door opener?
Over about fifteen years old, replacing is usually the better value, especially if the unit predates rolling-code security. Swapping an opener on a door whose springs and tracks are sound is straightforward work and much cheaper than a full door job.