How do I replace the garage door bottom seal?

The bottom seal is the rubber or vinyl strip (sometimes called the astragal) that runs along the very bottom of the door and presses against the floor. In Colorado it earns its keep against winter cold and blowing snow.

Identify your retainer and seal type

Before buying anything, look at the bottom edge of your door to see how the seal is held on. The seal type has to match the retainer.

• Aluminum retainer with two channels. Most modern steel doors have this. The seal has a T-shaped or double-bead edge that slides into the grooves. This is the easy case.
• Single-channel retainer. Older or lighter doors may use a one-groove track and a bead-style seal.
• Wood door with a nailed strip. Older wood doors often have a flat seal nailed or stapled to the bottom edge instead of a retainer.

Snap a photo of the end of the retainer so you can match the seal profile (T-style, bead, or U-shape) at the store. Buying the wrong profile is the most common mistake.

How to replace a garage door bottom seal

For the common aluminum two-channel retainer, the bottom seal replacement goes like this:

1. Measure the door width and buy seal a little longer than that. Seal sells by the foot in standard widths.
2. Open the door partway to a comfortable working height and support it, or work with the door down if you can reach the channel.
3. Pull the old seal out from one end. It slides along the channels. Spraying a little soapy water in the track helps it move.
4. Clean the retainer channels of dirt, old rubber bits, and grit so the new seal feeds smoothly.
5. Feed the new seal in at one end, lining up its beads with the two channels. Soapy water as a lubricant makes this far easier. Pull it through to the other side.
6. Trim the excess and center the seal so it overhangs evenly at both ends.

With the door closed, the new seal should press flat against the floor and close the gap. If your floor is uneven, a taller seal can bridge a low spot.

When the retainer itself needs work

Sometimes the seal is fine but the retainer is the problem. A bent, corroded, or missing retainer will not hold a new seal flat. Replacing the retainer means riveting or screwing a new aluminum track to the bottom of the door, which is a bigger job and one worth handing to a tech, especially on a heavy door where you would rather not fight the springs and balance.

Colorado winters are hard on the bottom edge. Road salt and snowmelt corrode the retainer and rot a cheap seal, so it is worth checking yours each fall. A fresh seal also helps the door not freeze to the slab when meltwater refreezes in the gap.

Keep the new seal lasting

A few habits make a seal last longer:

• Sweep grit and ice out of the channel so it cannot grind the rubber.
• Keep the bottom of the door and the floor clean where they meet.
• Pair the bottom seal with good side and top weatherstripping for a full seal, and keep the rollers and hinges lubricated so the door closes square. See our note on door lubrication.

If you still see daylight under a closed door after a new seal, the issue may be the floor or the door's balance rather than the rubber, which is covered in why there is a gap under the door.

When to call a pro

Swapping the rubber on a standard two-channel retainer is a fair DIY task. Call a tech when the retainer is damaged or missing, the door is heavy and hard to support, or a new seal still will not close the gap, which points to a door or floor issue.

Our crews across Denver, Lakewood, and the Front Range can replace seals and retainers, fix the underlying gap, and weatherproof the whole door, with flat-rate pricing. To get a drafty or leaking door sealed, call our 24/7 line at (303) 937-4477.