Replace a garage door bottom seal
Daylight, leaves and water coming in under the garage door usually means the bottom seal is cracked, flattened or torn. Replacing a garage door bottom seal is a manageable job on most doors with an aluminum retainer on the bottom edge. The key is buying the right shape of seal and working safely: the door must be locked so it can't move while you're near it. The hard part of this job is buying the right seal. Once it slides in, it's quick.
How a garage door seal works
Most modern steel doors have an aluminum channel, called a retainer, along the bottom edge. The rubber or vinyl seal slides into that channel by its edges, which are shaped like a T, a bead or a bulb. Older wood doors often have a seal nailed or stapled straight to the bottom instead.
The seal only works if it can press down and fill gaps along the floor. Over time it hardens, cracks and stops making contact. If the garage floor is uneven, a seal on the door may not be enough, and a threshold seal glued to the floor can close the gap.
Why the seal stops working
Cracked, flattened or torn rubber.
It won't fit or seal in the retainer.
The seal can't reach low spots.
The seal won't stay in the channel.
| You notice | Likely cause | Start at |
|---|---|---|
| Not sure which seal to buy | Seal type unknown | Steps 1 and 2 |
| Cracked or torn rubber | Worn-out seal | Steps 3 and 4 |
| New seal won't slide in | Dirty channel or wrong shape | Steps 5 and 6 |
| Seal creeps out at the ends | Ends not crimped | Step 7 |
| Daylight in low spots | Uneven floor | Step 8 |
Let's fix it
- Identify your seal typeLook at the end of the door's bottom edge where the seal enters the retainer. Note whether the seal edges are T-shaped, round beads or a bulb, and whether the retainer has one or two channels. Measure the channel width or take a piece of the old seal to the store. A seal with the wrong edge shape won't slide in.
- Measure the door widthMeasure the full width of the door. Buy a seal at least that long; most come in rolls you cut to length. Add a few inches so you have extra for trimming.
- Lock the door at working heightRaise the door to about waist or chest height with the opener. Unplug the opener so it can't be triggered by a remote or keypad. Clamp locking pliers or C-clamps onto the tracks just below a roller on each side, so the door can't roll down. Don't pull the emergency release cord with the door open; if a spring is weak, the door can drop.
- Slide out the old sealAt one end, grab the old seal and pull it out of the retainer along the length of the door. If it's stuck, pry the end loose with a screwdriver and work it out a little at a time. If the retainer ends are crimped, open them slightly with pliers first.
- Clean the channelWipe out dirt, grit and old bits of rubber from the retainer with a rag. Check for bent sections and straighten them gently with pliers. Spray the channels with soapy water or a silicone spray so the new seal slides easily.
- Feed in the new sealLine up the seal's edges with the retainer slots at one end. Have a helper feed the seal straight into the channel while you pull it from the other end. Keep it lined up and lubricated; if it binds, back up a bit rather than forcing it. On a long door, it can help to warm the seal in the sun first so it's more flexible.
- Trim and crimp the endsCenter the seal so it extends evenly at both ends, then trim it flush with the door edges using a utility knife. Gently squeeze the ends of the retainer with pliers so the seal can't creep out over time.
- Test and adjustRemove the clamps, plug the opener back in and close the door. The seal should compress slightly along the full width, with no daylight showing. If gaps remain because the floor is uneven, add a threshold seal glued to the floor under the closed door. If the door now reverses on closing, the opener's close-force or limit setting may need adjusting; check the opener's manual.
Watch it done
- No daylight under the closed door
- The seal touches the floor along the whole width
- The door closes and opens normally
If gaps remain
If light still shows at the sides or top of the door, the bottom seal isn't the issue. The side and top weatherstripping on the door frame wears out too and is a separate, simple replacement.
If the bottom of a wood door is rotted or the seal is nailed on, you'll need a seal made for nailing, or a technician can add an aluminum retainer.
What a pro typically charges (a rough estimate; prices vary by area): A garage door technician typically charges $150–$300 to replace a bottom seal, parts included. Replacing the retainer and seal runs about $200–$400, and a floor threshold seal installed costs about $100–$250.
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Garage door seal questions
How do I know what garage door seal to buy?
Match the shape of the seal's edges to the retainer on the door. Bring a piece of the old seal to the store.
How do I measure for a garage door bottom seal?
Measure the full width of the door and buy a few inches extra to trim.
Can I replace a garage door bottom seal myself?
Yes, on most doors with an aluminum retainer. Lock the door in place and unplug the opener first.
What if my garage floor is uneven?
Add a threshold seal glued to the floor to fill the low spots under the door.
Why is water coming in under my garage door?
Usually the bottom seal is cracked, flattened or torn. Replacing it is a manageable job on most doors with an aluminum retainer on the bottom edge.