Garage door weatherstripping and bottom seals
What the bottom seal does, how to tell when it needs replacing, the common seal types, and how replacement works. Includes when to leave it to a technician.
The rubber or vinyl strip along the bottom of your garage door does more work than it looks like. It blocks drafts, water, dirt and pests, and it wears out. This guide covers how to check it, the common seal types, and how replacement generally works.
What the bottom seal does
Clopay describes the bottom seal as a flexible strip that helps prevent heat loss at the bottom of the door and helps keep out water, dirt and pests. In a Clopay winter guide it calls the weather seal the easiest way to trap heat in and keep cold air out. The part is also called an astragal.
A seal that is cracked, flattened or pulled out of its channel lets all of those in. In New Jersey winters it also matters because water that gets under the door can freeze the seal to the floor. See winter garage door care in NJ.
What you can safely check
These checks are done with the door closed and at rest. They need no tools and no contact with springs, cables or brackets.
- Look for daylight. Clopay says that if you can see a gap between the bottom of the closed door and the driveway or floor, the seal should be replaced.
- Feel for a draft. Clopay says to place your hand along the bottom of the door and replace the seal if you feel a draft.
- Look for cracks and wear. Clopay says a cracked or worn seal is due for replacement. Cold can crack a seal, so look in spring after winter.
- Look at the ends. Check that the seal has not slipped out of its channel at either end.
- Check the floor. If water pools at the door line, the seal may not be sealing, or the floor may need attention.
Clopay suggests checking in spring for winter cracking and in fall, before cold weather, replacing any damaged sections. Add the seal to your annual maintenance checklist.
Common seal types
Family Handyman lists the common types below. Which one fits your door depends on the retainer, the channel on the bottom of the door, so the existing retainer sets your options.
| Type | How it works | Notes from the source |
|---|---|---|
| U-shaped beaded seal | A flat strip with beaded edges slides into a retainer on the door bottom and forms a U against the floor. | Flexible enough to fill depressions in uneven pavement. Needs a matching retainer. |
| Bulb-shaped (tube) seal | A closed loop of rubber or vinyl with a channel on top that fits a single-track retainer. | Doors with two-track retainers need a different bulb seal. |
| T-style seal | A T-shaped channel fits the retainer track. | Check the track shape first, since rounded and T-style tracks are not interchangeable. |
| J-style seal | A flap that bends into a J when the door closes. | Often used on wooden doors without a retainer. The retainer width must match the door thickness. |
| Self-adhesive strip | Attaches to the outside bottom of the door and splays against the pavement. | Described for wooden canopy and retractable doors, and also sectional and rolling doors. |
Family Handyman says rubber stays flexible in cold weather while vinyl tends to stiffen as temperatures drop, so it calls rubber the better choice in colder climates. It describes vinyl as often slightly more affordable and more durable. Clopay says to contact it for the correct seal type for your retainer design, and its replacement instructions give different parts for bulb-shaped and U-shaped seals. Manufacturers differ, so match the seal to your door and check its manual.
How replacement generally works
Clopay lists the bottom seal among the parts a homeowner can replace, and its instructions for a bulb-shaped seal show the general pattern. Your door's design may differ.
- If the door is on an opener, disengage it first. Clopay's instructions say to do this before starting.
- Raise the door fully open and clamp both tracks directly below the door, as the instructions describe, so it cannot come down.
- Remove the old seal from the bottom of the door. You may need to take out screws holding it to the retainer.
- Feed the new seal's T-shaped top into the retainer slot and slide it along the door. Clopay says soapy water helps it slide.
- Trim the excess, leaving about two extra inches at the edge and tucking it in, as Clopay describes for the bulb-shaped seal.
- Replace any screws you removed, lower the door, and check that the seal sits evenly on the floor.
Do not work under a door you cannot trust
Replacing a seal means working beneath a raised door. Do not do this if the door is heavy, crooked, off its track, or has a spring or cable problem. Do not touch the springs, cables or bottom brackets. Clopay warns that the bottom brackets must not be removed while the door is under tension. If you are not sure the door is sound, have a technician do it.
When to stop and bring in a technician
- The door is not level, so the seal sits unevenly no matter what you replace.
- The retainer is bent, rusted or missing, or you cannot tell which seal fits.
- The bottom of the door or the panel has been damaged by forcing it open against ice.
- The door is heavy, noisy or jerky, or a spring, cable or track shows damage. See when a garage door is unsafe to use.
- You are not comfortable clamping the tracks and working under a raised door.
Our technicians check the bottom seal, retainer and door alignment together, and confirm what is needed before replacing the seal. See weather seal replacement for the service, and garage door repair if the door itself needs work.
Seals and insulation
A new seal helps with drafts and water, but it does not change the door's insulation. Clopay says insulated doors can keep an unheated garage 10 to 20 degrees warmer on a cold winter day, and that rooms next to an attached garage can feel colder than the rest of the house. For how door construction affects this, see insulated vs non-insulated garage doors. To judge when a whole door is worth replacing, see repair or replace the whole door.
Related services
Sources
Need a technician?
If something on your door looks damaged, stay clear and let a technician handle it.
Questions and answers
How do I know if my garage door seal needs replacing?
Clopay says to replace it if it is cracked or worn, if you feel a draft when you hold your hand along the bottom of the door, or if you can see a gap between the closed door and the floor.
Is rubber or vinyl better for a garage door seal?
Family Handyman says rubber stays flexible in cold weather while vinyl tends to stiffen, so rubber is the better choice in colder climates. Vinyl is often slightly more affordable and durable. Match the seal to your door's retainer.
How often should I check the bottom seal?
Clopay suggests checking in spring for winter cracking and in fall to replace damaged sections before cold weather.
Do all garage doors use the same seal?
No. The retainer on the bottom of the door sets which seals fit. Family Handyman notes that rounded and T-style tracks are not interchangeable, and that doors with two-track retainers need a different bulb seal.
Can I replace the bottom seal myself?
Clopay lists it among the parts a homeowner can replace, with the door sound and the tracks clamped. Do not do it if the door has any sign of spring, cable or track trouble. A technician can do it safely.
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