“My Garage Door Has a Gap at the Bottom”
What Causes a Gap Under the Door?
Ranked from most to least common, and note that the shape of the gap is diagnostic: an even gap across the width has a different cause list than a wedge that is wider at one end.
- 1 A worn bottom seal: the vinyl or rubber astragal flattens, cracks, and shrinks with age and sun, leaving an even gap or several small ones. The most common cause and the cheapest fix.
- 2 A settled or uneven slab, concrete sinks and wears over the years, and a perfectly straight door cannot follow a floor that no longer is. The gap is usually consistent in location across seasons.
- 3 Opener travel limit set short: the opener stops the door a touch above full compression of the seal, leaving a slim, even gap. Sometimes appears after an opener swap or a power-loss reset.
- 4 One side sitting high, a wedge-shaped gap, wider at one end, points to a cable, drum-timing, or track issue holding one corner up. If this is new, treat it as the early stage of a crooked door.
- 5 Door or track out of plumb from house settling: the longest-term cause, usually alongside visible rubbing elsewhere.
Which Checks and Fixes Can You Safely Do Yourself?
The seal and the floor are yours; the lift system is not. Safe steps:
- Inspect the bottom seal with the door closed: flattened, cracked, torn, or shrunken vinyl is your answer. Most seals slide into a retainer track along the door's bottom edge, and replacement bottom seals in the correct profile are a legitimate homeowner job on most doors.
- Map the gap: even across the width points to seal or travel limit; localized dips point to the slab; a wedge points to the lift system.
- For slab dips, an oversized or threshold-style seal bridges modest unevenness, a floor-mounted threshold strip pairs with the door seal to close larger low spots.
- Watch the door finish its close: if it stops moving visibly above the floor and the seal never compresses, the travel limit is the suspect. Note it for the technician rather than adjusting force or limits yourself.
- If the gap is wedge-shaped and new, stop there: look at cables and springs from a distance only, per our crooked-door guide, and do not keep cycling the door.
When Should You Call a Professional?
Call for the wedge, a one-sided gap that was not there last month means one side of the lift system is holding the door high, and cables, drums, and track are load-path components no homeowner should adjust. Caught early it is a quick re-seat or re-tension; ignored, it graduates into the crooked, jammed door that becomes an emergency call.
Also call when the fix is a travel-limit or force adjustment (a technician sets both to spec with the safety systems verified), when the slab has settled beyond what seal profiles can bridge (options range from threshold systems to slab repair), or when a seal replacement reveals rot or rust along the door's bottom edge. And since a sealed door is also a defended door (gaps admit water, drafts, and pests, and an ill-fitting door is easier to pry) our safety and security hub covers the fuller picture.
Gap at the Bottom FAQs
Common homeowner questions
Straight answers first: your local team can go deeper on anything specific to your door and your home.
How do I fix a gap under my garage door?
Start with the bottom seal: if it is flattened, cracked, or shrunken, a replacement seal in the correct profile, slid into the retainer along the door's bottom edge, closes most even gaps. For floors that have settled unevenly, an oversized seal or a floor-mounted threshold strip bridges the low spots.
Why is the gap only on one side of my garage door?
A wedge-shaped gap means one side of the door is sitting high, which points to the lift system, a cable off its drum, slipped drum timing, or a track issue. Those are under-tension components, so do not adjust anything; if the wedge is new, stop cycling the door and have a technician re-seat it.
Can I adjust my opener's travel limit to close the gap?
We recommend leaving limit and force settings to a technician. Set too far, the opener jams the door into the slab and strains the whole system; set with force raised to compensate, the door's crush protection is weakened. It is a five-minute professional adjustment done with the safety tests that should follow it.
Does a gap under the garage door matter if it's small?
More than it looks: even a slim gap admits rainwater, drafts that undo an insulated door's benefit, and pests, mice famously need very little clearance. It also marks the door as ill-fitting, which is an invitation to prying. A seal is one of the cheapest components on the whole door to renew.
From reading to fixing
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