Gap Under Your Garage Door: Causes and Fixes

You close the garage door and daylight still shows along the bottom edge. Cold air, dust, and the odd mouse find their way in through that thin line, and most homeowners assume the whole door is the problem. It usually is not.

A garage door gap almost always comes from one specific part that wore out or moved, and once you know which one, the fix is often quick. If you want us to take a look in person, we can send someone out for a full repair visit.

Where the Gap Comes From

Close the door and check the bottom edge from inside with a light behind it. The shape of the garage door gap tells you almost everything you need to know before you touch a single part.

An even gap across the whole width usually points to a worn bottom seal or an opener limit set wrong. A gap on one side that grows wider toward the edge usually means the door has shifted out of level. A gap only in the middle, with both edges still flat against the floor, usually means the concrete under the center of the opening has moved.

The Bottom Seal Wears Out First

The bottom seal is the rubber strip that runs along the base of the door and presses against the floor. It is a wear item, not a permanent part. Denver’s dry air and strong summer sun bake this rubber over the years, and it hardens and cracks. Once that happens, the seal no longer presses flat against the floor, and a garage door gap opens up along the full width of the door.

A new seal is often a simple fix on a standard door. The old strip slides out of its track, and a new one slides in, matched to the track style your door already uses.

The Door Has Shifted Out of Level

If the gap runs wider on one side than the other, the door itself may have dropped or tilted. This can happen when a spring loses tension on one side, when a hinge wears down, or when the track pulls slightly out of line. We can check your springs and track together, since a weak spring on one side is the most common reason for a lopsided garage door gap.

Do not try to adjust spring tension on your own to fix this. Springs hold a lot of force, and the wrong change can cause the door to drop fast and without warning.

The Concrete Floor Has Shifted

Denver’s freeze and thaw cycle moves concrete more than most people expect. Ground under the slab expands and pulls back through the winter months, and this can raise or sink the floor right under the center of the door opening. When that happens, the middle of the door closes flush while both edges still touch, so the gap shows up only in the center.

A shifted floor is not a problem you fix at the door. A threshold seal strip glued along the low spot is usually the most practical answer, since it can flex to match the shape of the floor underneath it.

The Opener Limit Is Set Wrong

Sometimes the door itself is fine, but the opener stops it a few inches early on every close. This is a setting inside the opener, not a broken part, and a tech can usually correct it in minutes.

If your door used to close flush and now stops short every time, check this before you assume something is broken.

Why a Small Gap Matters More Than It Looks

A garage door gap is not just a minor eyesore. It lets in cold air that raises what you pay to heat the garage, lets rain and snowmelt track across the floor, and gives mice and insects an easy way inside. In an attached garage, a gap can also let engine exhaust drift toward the door that leads into your house, which is a real safety concern and not just a comfort issue.

What to Do Next

Start with the shape of the garage door gap, since that alone points you toward the likely cause. A worn seal is often a simple fix you can handle yourself. A tilted door, a weak spring, or a shifted floor needs a closer look from someone with the right tools, and a wrong attempt on your own can make things worse or cause an injury. If two or more causes overlap, a garage door gap can be tricky to solve piece by piece, so a full inspection saves you from guessing twice.

We also handle maintenance visits built to catch a small garage door gap before it turns into a bigger repair bill, and our team can check your opener settings on the same visit if the door stops short every time.

If your garage door gap has not closed up no matter what you try, call us at (833) 435-8883. A garage door gap rarely fixes itself, and we will send a technician out to find the real cause and fix it the same day in most cases.