Why Is There a Gap Under One Side of the Garage Door?

No. A very thick seal can fold, freeze or create closing resistance. Alignment and slab shape should be understood first.

A cable problem is one possibility. Track, roller, spring and section issues can also create an uneven door.

It can help in some openings, but grading, drainage and the volume or direction of water remain important.

Most often the two cables are no longer holding the door level — one has stretched, slipped on its drum, or come off. It can also be a bent bottom section after an impact, a settled or sloping slab, or a bottom bracket pulling away. The gap is worth acting on: it lets weather, water and animals in and often signals a lifting problem.

Frequently, yes — an uneven bottom edge usually means one side is not being lifted the same as the other, and a stretched, slipped or displaced cable is the common cause. Because a cable problem is a stop-use situation, a sudden one-sided gap is worth having checked rather than sealing over.

That treats the symptom, not the cause. If the door is not closing level because of a cable or a bent section, a thicker seal hides it while the underlying problem — and the risk it carries — remains. The door should be brought level first, then sealed.

Yes — a slab that has settled, heaved or sloped over time leaves an uneven surface the door cannot seal against evenly, and freeze-thaw is hard on garage slabs in Vermont. Where the door is level but the floor is not, a threshold seal or addressing the slab is the answer rather than door hardware.

It can be both — a gap large enough to see daylight is an easy entry for mice, insects and drifting snow, and it undermines the door's job of closing the opening. That is a practical reason to fix the cause rather than live with it, beyond the appearance.

If the bottom section is bent or creased, an impact is a likely cause, and that is a structural repair rather than a seal or cable adjustment. A door hit hard enough to bend the bottom section often needs that section replaced and the cables and track checked alongside.

Cold and ice can expose or worsen it — a slab that heaves with freeze-thaw, or ice building unevenly at the threshold, can leave one side higher. And a cable that has been marginal can slip under the extra winter load. So a gap that shows up in winter can be seasonal, mechanical, or both.

If the gap is from a settled floor and the door otherwise runs level and true, it is mostly a sealing issue. If the door is sitting crooked, or the gap came with a bang or a slack cable, treat it as a lifting problem — stop using the door and have the cause found before operating it further.

Which side has the gap, whether the door looks crooked or level otherwise, whether it appeared suddenly or gradually, whether there was an impact, and whether you can see a slack cable from a distance. That helps separate a cable or hardware problem from a floor or seal one.