Short answer
To fix a gap under the garage door, replace the bottom seal. Raise the door to about waist height, unplug the opener and clamp locking pliers on both tracks just below a roller. Slide the old rubber out of the channel on the bottom edge and slide the new one in. Trim the ends, remove the pliers, plug the opener back in and close the door.
Safety first
Never put your body under the raised door. Clamp both tracks so it can’t roll down, and keep the opener unplugged while you work. If the door won’t stay put on its own, stop: the springs need a technician.
How to replace the bottom seal on a garage door
1Light, leaves and bugs get in under it
The rubber seal on the bottom edge cracks and flattens with age. If you see daylight under the closed door, it is time to replace it.
Read all the steps
- Light, leaves and bugs get in under it. The rubber seal on the bottom edge cracks and flattens with age. If you see daylight under the closed door, it is time to replace it.
- Raise it waist high, unplug it, clamp it. Open the door to about waist height. Unplug the opener and clamp locking pliers on both tracks, just below a roller, so it can’t come down.
- Slide the old seal out. The seal sits in a metal channel along the bottom edge, called the retainer. Pull it out from one end. A little soapy water helps it slide.
- Slide the new seal in. Feed both edges of the new seal into the slots of the channel and pull it through. Trim the ends with a utility knife.
- Unclamp, plug in and close it. Remove the pliers, plug the opener back in and close the door. No more daylight along the bottom? Done.
- Still not fixed? Call a garage door company Especially if: the door won’t stay up on its own when you raise it.
Garage doors near you
Share your location and we will show the nearest ones with their phone number.
Or pick your city:
Before you buy
- Cut a small piece of the old seal and take it to the store: the shape of its edges must match the channel.
- Measure the width of the door and buy a little extra.
- If the metal channel is rusted or bent, the seal won’t slide in. The channel can be replaced too.
If the gap is bigger on one side
A seal can’t fill a big, uneven gap. The floor may slope, or the door may be out of level because of a cable or spring problem. A rubber strip glued to the floor helps with a sloped floor. A crooked door needs a technician.
What not to do
- Do not reach or crawl under the door, even with the pliers on.
- Do not touch the brackets at the bottom corners where the cables attach. They are under tension.
- Do not run the opener while the pliers are on the tracks.
When to call a garage door technician
- The door won’t stay up on its own when you raise it.
- The gap is much bigger on one side.
- The bottom channel is rusted through or bent.
- The cables or brackets at the bottom corners look frayed or loose.
Frequently asked questions
How do I fix a gap under my garage door?
Replace the bottom seal if it is cracked or flat. If the gap is uneven, add a rubber strip on the floor or have a technician level the door.
Can I replace a garage door bottom seal myself?
Yes, on doors with a channel along the bottom edge. Raise the door to waist height, unplug the opener and clamp both tracks before you start. Never work under the door.
What size bottom seal do I need for my garage door?
It depends on the channel on your door. Cut a small piece of the old seal and match its shape and width at the store.
How often should a garage door bottom seal be replaced?
When it is cracked, stiff, torn or lets daylight through. Strong sun and cold winters wear it out faster.
Why is there light under my garage door when it is closed?
The bottom seal is worn, the floor is uneven or the door is not closing all the way. A seal fixes small, even gaps. A big gap on one side needs a technician to check the door.