Garage door bottom seal replacement

By Heather Window & Door · 11 September 2026 · Updated 24 September 2026

What the seal is, and what it is doing

Along the bottom edge of the door there is an aluminum or steel retainer with a rubber or vinyl strip held in it. The strip squashes against the floor as the door lands, closing the gap between a straight door and a slab that is never quite flat.

It also takes the abuse. Sun, cold, rain, grit, a car tire, a string trimmer line. Rubber hardens and cracks, vinyl shrinks and tears, and the strip at some point stops touching the floor along its whole length. A North Texas summer is hard on it: what summer heat does to a door, and what a cold snap does.

Separately, the seals down the sides and across the top of the opening — the stop molding — do the same job at the edges. They are a different part, and they fail differently.

How to tell whether it is the seal or the door

Close the door and look along the bottom from inside, with the garage light off. Daylight tells you most of what you need to know.

• Light in one thin even line Usually a worn or shrunken seal. A straightforward replacement.
• Light at one end only The door is not landing square, or the floor drops away. A new strip alone will not close it.
• Light in the middle, sealed at both ends Often a section that has bowed, or a seal that has pulled out of its retainer in the middle.
• The seal is crushed flat The door is traveling too far down — a limit setting, and sometimes a symptom of something else.
• Water tracking in along one wall Look at the side seals and at the slope of the slab before blaming the bottom.
• Daylight at the top corners That is the stop molding, not the bottom seal.

Replacing it, if that is what it is

With the door fully closed, the strip slides out of the retainer at one end and the new one slides in the same way. The two things that catch people out are getting the right profile and getting the length right.

• Profile first. Retainers take specific shapes of strip, and a strip with the wrong bead will not stay in.
• Measure the door’s width and buy long, not short. Trim at the end.
• A little soapy water helps a stiff strip through the channel.
• Keep the door closed while you work, and do not lift it to get a better angle.
• Do not undo the bottom brackets at the corners of the door for access — that is where the lift cables anchor, and there is stored energy behind them.

If the retainer itself is bent, split or corroded, that is a different job, and it is worth having looked at rather than forced.

Water still coming in with a good seal? Look at the slab

DASMA, the door makers’ association, notes that rainwater getting past the bottom edge of a sectional door is common on exterior-facing doors. It describes two fixes that are built into the floor rather than the strip: a slightly inclined lip that the door rests on, or a notch in the edge of the slab that the door can sit down into.

That is a floor detail, not a part you can buy, and it is worth telling us about when you ask for a seal.

When it comes to us instead

A seal that keeps failing is usually reporting something else: a door out of balance landing heavily, a bowed section, a floor that has settled, or limits that push the door into the slab on every cycle.

A visit for a seal is also a visit that gets the safety check we do on every visit — auto-reverse tested, photo-eyes aligned, springs and cables inspected, door balanced — so the reason the seal failed gets found rather than replaced again next year. The number is on the written estimate first, and the invoice matches it. Garage door repair is the page for that visit.

Sources

1. Clopay — residential garage door service and support
2. Raynor — garage door safety and care
3. DASMA — Technical Data Sheet 197, “Water Infiltration Under the Bottom of a Sectional Door”

All sources read 8 September 2026. Linked so you can check them rather than take our word for it.

Written from the manufacturers’ own published guidance — every source is linked above.

Describe it however makes sense to you

Read enough? Tell us about the door.

However you describe it is enough — no part names needed. The visit and the written estimate cost you nothing, and nothing starts until you approve the number.

• However you describe it is enough. No part names needed.
• The written estimate is free. Nothing owed if you pass.
• Nobody starts the repair until you approve the number.