A garage door that sits uneven — one side higher than the other, a diagonal gap at the bottom, or a door that binds as it moves — is a mechanical problem with a limited set of causes. It is not normal, and it does not fix itself.
The most common reason is a broken or weakened spring on one side. But a cable that has slipped off a drum, a track that has shifted, or a hinge that has bent can produce the same symptom. You need to tell them apart before you decide what to do next.
What physically happens when a door goes uneven
A sectional garage door is a counterweight system. The torsion spring (or pair of extension springs) carries most of the door’s weight so the opener only has to move it, not lift it. That balance has to be equal on both sides.
When one spring loses tension — because it broke, because it fatigued, or because the cable connecting it to the bottom bracket came loose — the side with less tension drops. The other side stays up. The door now hangs diagonally.
The same thing happens if a cable jumps off its drum. The cable drum sits at each end of the torsion shaft. The cable wraps around it in grooves, and the bottom bracket pulls the cable down as the door opens. If the cable slips out of its groove, it loses its mechanical advantage. That side drops.
Tracks and hinges are less common but worth knowing. A track that has been struck by a car or pushed out of plumb by a settling foundation will force the door to bind. A bent hinge — usually from a hard close or a door that was forced when something blocked it — changes the angle of that panel relative to the rest. The door looks crooked because it is physically crooked.
How to tell a spring problem from a cable problem from a track problem
You can narrow it down without tools, but you need to look at specific things in a specific order.
First, look at the gap at the bottom. Stand outside and sight across the bottom edge of the door. If one side is lower by half an inch or more, that is the side with the problem. Now look at the spring above that side. A torsion spring is mounted on a steel shaft above the header. If the spring is in one continuous piece, it is intact. If there is a gap in the middle — a clean break — that spring is done. The door will not lift safely.
Second, check the cable on the low side. The cable runs from a drum at the top down to a bracket at the bottom corner of the door. It should be taut and sitting squarely in the drum’s grooves. If it is slack, frayed, or riding on the shaft instead of the drum, the cable has come off. This can happen from a sudden stop or from normal wear if the cable was already corroded. In Metro Vancouver’s coastal climate, salt air accelerates that corrosion. Cables on older doors in Burnaby or Surrey — especially 1960s to 1980s builds — are often the original set and should be inspected annually.
Third, look at the track on the low side. Stand back and run your eye down the vertical track from top to bottom. It should be straight and parallel to the door edge. A track that bows inward or outward will pinch the roller. You can test this by lifting the door manually a few inches (with the opener disconnected) and watching whether the roller binds in the track.
Fourth, check the hinges. Open the door halfway and look at the hinges between each panel on the low side. A hinge that has bent will cause that panel to sit at a different angle than the one above it. The door will look uneven at that panel line, not just at the bottom.
Safe DIY checks for an uneven garage door
You can do the visual checks above. You can also test whether the door is balanced — but only if you know the spring is intact.
To test balance: disconnect the opener using the red emergency release cord. Lift the door manually to about waist height. Let go. A properly balanced door stays put. If it falls, the springs are weak. If it shoots up, the springs are too tight. If one side drops and the other stays, you have found your uneven side.
Do not attempt to adjust or replace springs yourself. A torsion spring under tension stores enough energy to break bones. Extension springs are under tension when the door is closed and can snap loose with force. The industry has a simple rule: if you have not been trained to work on springs, you do not touch them. That is not a gatekeeping line. It is a description of what happens when a 250-pound spring releases unexpectedly. A technician uses winding bars and follows a specific procedure. There is no safe shortcut.
What a technician checks during an uneven-door service call
For a broken spring, the technician measures the wire gauge, inside diameter, and length of the old spring. They match it to the correct replacement — spring rate is specific to door weight and height. They wind the new spring to the correct number of quarter-turns, install new cables if needed, and test the balance.
For a cable off the drum, the technician re-seats the cable in the drum grooves, checks the cable for fraying or kinking, and replaces it if there is damage. They also check the bottom bracket — a cable that came off once may have bent the bracket.
For a shifted track, the technician loosens the track brackets, re-plumbs the track with a level, and tightens everything back down. They check the roller condition at the same time, since a worn roller can cause tracking problems.
For a bent hinge, the hinge is replaced. This is a straightforward fix but requires the door to be supported while the hinge bolts are removed.
What drives the cost of an uneven-door repair
The cost depends entirely on what is wrong. A hinge replacement is a parts-and-labour job under an hour. A cable replacement takes a bit longer and includes new cables on both sides — you do not replace one cable alone because the other is at the same age and will fail soon. A spring replacement is the most expensive of the common fixes because the spring itself costs more and the labour involves precise winding under tension. A track replacement is in between — the track is cheap but the labour to remove and reinstall it takes time.
The specific hardware on your door matters. Older doors in New Westminster’s Queens Park neighbourhood, for example, often have non-standard opening sizes that require custom-ordered springs. A standard 16-foot door in a Fleetwood townhome uses off-the-shelf parts. The repair cost differs because the parts differ.
How to prevent a garage door from becoming uneven again
Uneven doors are almost always a symptom of deferred maintenance. Springs have a finite cycle life — typically 10,000 to 15,000 cycles for standard-torsion, or about 7 to 10 years of normal use. Cables corrode from the inside out, especially in coastal salt air. Tracks shift when brackets loosen over years of vibration.
Annual maintenance catches these things before they fail. A technician lubricates the springs, checks the cable tension, tightens the track brackets, and tests the balance. In Richmond or Delta, where winter damp and salt air are constant, annual service is cheap insurance. In Coquitlam’s Burke Mountain area, where many doors are still under builder warranty, a maintenance visit also preserves that warranty — most manufacturers require proof of regular service to honour a claim.
If your door is uneven, stop using it. A door that is off-balance puts extra load on the opener, the tracks, and the cables. The longer it runs crooked, the more parts get damaged. A spring that breaks while the door is moving can drop the door suddenly. A cable that snaps under load whips across the garage.
Call a technician. The fix is usually straightforward, and the cost of the call is less than the cost of replacing a door that was damaged by running it broken.