The short answer

Water under a garage door is a water-path problem, not automatically a gasket problem. Look at the door’s bottom seal, side seals, threshold contact, slab slope, driveway, gutters, and nearby downspouts together. A new rubber seal cannot stop water that flows around the jamb or ponds against an uneven floor.

Check each boundary

Boundary Observation What it separates
Bottom seal Cracks, flattening, gaps, or light under the door Door-to-floor contact.
Threshold Continuous contact and secure edges Water that runs toward the door.
Side seals Compression and gaps at both jambs Wind-driven rain and splash.
Slab Low corner, crack, or standing water Building drainage versus door hardware.
Exterior runoff Downspout, driveway, and roof water The source may be outside the door.

Clean the contact area and photograph it closed. Do not place fingers near hinges, rollers, cables, or a moving door. If the door is difficult to balance, reverses unexpectedly, or has damaged cables, stop the weather-seal project and call a garage-door professional.

Compare replacement materials

Measure the existing retainer, seal profile, door width, and threshold height before ordering. A thicker seal may reduce clearance or change the door’s closing force. The estimate should separate seal, retainer, threshold, slab or drainage work, and any opener or alignment service.

Limits

This guide does not authorize spring, cable, track, or opener adjustment. Those components can cause serious injury when handled incorrectly.