Garage Door Sagging or Closing Unevenly: Causes

A garage door that sags in the middle, hangs lower on one side or closes with a gap along the floor is telling you that something in the system is out of balance. The usual causes are a stretched or slipped cable, a weak or broken spring, a bent track, or a door section that has cracked or lost its hinges' grip. Some of these are safe to look at from the floor. Most are repairs for a technician, because the parts involved are under heavy tension.

Why does one side of my garage door hang lower than the other?

The most common cause is a cable problem. A door hangs from a cable on each side, and if one cable slips off its drum, stretches or frays, that side drops while the other holds. A broken spring on a two-spring system can do the same, because one side is then carrying less of the load. If the low side is accompanied by a loose, drooping cable, stop using the door and read our guide to a snapped or frayed cable.

Why does the middle of the door sag when it is open?

A sagging centre usually means the door sections are flexing because they lack support. Wide doors, especially double doors, need a strut or reinforcing bar across the top of each section. Over time, an unreinforced section, a door that has lost some of its stiffness, or hinges that have loosened can let the door bow. A bowed section often cracks at the hinge points next. Adding a strut is a common fix, but only once a technician has checked the panel for cracks.

Can weak springs make a door close unevenly?

Yes. Springs lose strength with use, and a door that was balanced years ago may now be heavier than the springs can support. You will notice the door slamming shut, being hard to raise, or the opener straining. If the door will not stay put halfway when you lift it by hand, the balance is off. Our guide to a garage door that is heavy to lift explains how to check balance safely. Do not adjust springs yourself.

How do I check my door without taking risks?

Do a visual check from the floor with the door closed. Do not touch the springs, cable ends or the brackets at the bottom corners. Look for:

• A cable that looks loose, bunched on the drum or hanging off the pulley.

• A visible gap in a torsion spring above the door.

• Rollers sitting out of the track, or a track that looks bent or pulled from the wall.

• Cracks around the hinges, or a section that is bent or bowed.

• A uneven gap at the bottom, where one corner touches the floor and the other does not.

Take photos of anything that looks wrong. They help us judge the problem before we arrive.

Can a crooked door damage the opener?

It can. An opener is built to move a balanced door, not to drag a crooked one. If the door is binding on one side, the opener works against the extra load, and that wears the gears and the drive. Many stripped gears and burnt-out motors start with a door that was out of balance for months. If the door is crooked, stop using the opener until the cause is found and use the emergency release only if the door is stable.

Is it a cable, a spring or a track problem?

A rough guide helps. One side low with a slack cable points to the cable. A door that is heavy, slams or will not stay halfway points to the springs. A door that catches, scrapes or jumps in the same place every time points to the track or a roller. A broken spring has its own steps, covered in our guide to a broken garage door spring. Often more than one thing is wrong at once, which is why a hands-on check matters.

What does a repair involve?

A technician will check balance, cables, springs, tracks, rollers and hinges together, because fixing one part while a worn one remains tends to bring the problem back. Depending on what we find, the work can include resetting a cable on its drum, replacing worn cables or springs, realigning or replacing a track, adding a reinforcing strut, or replacing a damaged section. We then rebalance the door and test the opener.

Can I keep using a door that is slightly crooked?

It is best not to. A small tilt is often the first sign of a cable about to slip or a spring about to fail, and either can bring the door down fast. Leave the door closed, switch the opener off if the door is binding, and book a visit. It is also a security problem, since a gap at the floor lets cold air, pests and people in.

Want a technician to look at a sagging door?

Modern Empire Doors is at 138 Yorkland St, Richmond Hill, and we are available 24/7, serving the GTA since 2018. We are top rated on Google. Call 647-323-1826 and send us a photo of the door from inside and outside, with a close-up of the low corner and the cable on that side. We will tell you what is likely wrong and how soon it needs attention.