There is a gap under my garage door. Who do I call?
Usually, start with
Garage-door professional
If a closed garage door leaves a visible gap at the bottom, a garage-door professional commonly evaluates door alignment, travel, bottom seal condition, and how the door meets the floor or threshold.
Change course if
The floor or threshold is visibly uneven
Concrete repair or leveling expertise may also be relevant when the surface itself is preventing even contact.
The gap appeared after the slab or driveway moved
Concrete or structural expertise may be relevant when the opening change follows broader movement.
Water is being directed toward the gap
Drainage expertise may also be relevant when runoff is contributing to the problem.
Who handles what
Garage door
Evaluates door alignment, closing position, weather seals, and contact with the threshold.
Concrete repair / leveling
Evaluates an uneven slab or threshold that prevents consistent contact across the opening.
Drainage
Evaluates water movement toward the garage when the gap is also a water-entry path.
What might be happening
A bottom gap can come from the door, the seal, the surface beneath it, or a combination of those conditions. The location and shape of the gap help distinguish an opening problem from an uneven floor or threshold.
Useful things to notice
Where the gap is largest
A gap at one corner, the center, or across the full width can provide useful context.
Whether the bottom seal is intact
Torn, compressed, missing, or hardened seal material is useful to document.
Whether the floor line is even
Visible dips, slopes, or elevation changes beneath the door can affect contact.
Before you call
Photograph the full closed door from inside and outside, then take closer photos of the gap, bottom seal, and floor or threshold beneath it.
Before you fix the visible symptom
Adding a larger seal may hide a small gap but may not address door alignment or an uneven threshold. Identifying which surface is out of position first can avoid repeated weather-seal changes.
References
Door & Access Systems Manufacturers Association. Technical Data Sheets: Commercial & Residential Garage Door, including TDS 167, Residential Sectional Garage Door & Electric Operator Checklist, and TDS 197, Water Infiltration Under the Bottom of a Sectional Door.
Door & Access Systems Manufacturers Association. DASMA Standards, including ANSI/DASMA 102-2018, Specifications for Sectional Overhead-Type Doors.