How to Seal the Gaps Around Your Garage Door
To seal the gaps around your garage door, replace the bottom rubber seal (the astragal) that runs along the floor, then add or replace the weatherstripping on the top and sides of the door frame. For uneven floors, swap in a threshold seal that mounts to the concrete. Most homeowners can knock this out in an afternoon with a tape measure, a utility knife, and a screwdriver or drill.
Step by step
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1
Find where the air and light are getting in
Pull the door shut and stand inside the garage in daylight (or have someone shine a flashlight from outside at night). Daylight along the bottom usually means a worn bottom seal; light down the sides points to flattened jamb weatherstripping; gaps at corners often mean the door isn't sitting square. Run your hand around the perimeter to feel for drafts so you know exactly what to buy.
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2
Replace the bottom seal (astragal)
Most steel and aluminum doors have a retainer track on the bottom edge with a T-shaped or P-shaped rubber seal slid into it. Slide the old one out (a little dish soap or silicone spray helps), measure your door's width, and cut a new seal to length. Feed the new bead into the channel from one side. If your door has a wood bottom rail instead, the seal is nailed or screwed on, so pry off the old one and fasten the new one flush.
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3
Add a threshold seal if your floor is uneven
If the concrete is cracked, sloped, or the door still won't close tight, a threshold seal is your friend. This is a wide rubber or vinyl strip that bonds to the garage floor right under the closed door. Dry-fit it, mark the line, clean the concrete thoroughly, then bed it in the manufacturer's adhesive. Pair it with the bottom seal and you'll block water, leaves, and most critters.
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4
Replace the side and top weatherstripping
The flexible vinyl or rubber strip nailed around the wood door stop (jamb) is what seals the sides and top. Pry off the cracked, brittle pieces, measure each run, and cut replacement stop-mounted weatherstrip to fit. Nail or screw it so the flexible flap presses lightly against the closed door panel, snug but not so tight it binds the door or strains the opener.
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5
Seal the frame-to-wall joint with caulk
Air and water also sneak in behind the door frame where the wood trim meets the siding or block. Run a bead of paintable exterior silicone or polyurethane caulk along that outside seam, top and both sides. Skip the very bottom of the side trim so any water that does get in has a way to weep back out.
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6
Close the door and recheck your work
Lower the door and repeat the daylight test. The seals should make light, even contact all the way around with no visible gaps. If one corner still shows daylight, the door may need a track or spring adjustment to sit square, which is a sign it's worth a closer look rather than just adding more rubber.
When to call a pro
Call a pro if the door still won't seal evenly after new weatherstripping, if it sits crooked in the opening, or if you see frayed cables or hear grinding, since those point to track, roller, or spring problems that aren't safe to DIY.
Call (888) 290-7421Frequently asked
How much does it cost to seal the gaps around a garage door?
If you do it yourself, a new bottom seal runs about $15 to $40, side and top weatherstripping is roughly $20 to $50 for a standard door, and a threshold seal kit is around $30 to $60. Doing all of it yourself usually lands under $100. Having a pro replace all the seals typically costs $150 to $350 including parts and labor, depending on your door size and door type.
How often should I replace my garage door weatherstripping?
Most rubber and vinyl seals last about 3 to 5 years before they harden, crack, or flatten out, though hot sun and freezing winters can shorten that. A quick way to check: if the seal feels stiff instead of springy, or you can see daylight under a closed door, it's time to replace it.
Why is there a gap on just one side of my garage door?
A gap on one side usually means the door isn't sitting square in the opening. That can come from a track that's shifted out of alignment, worn rollers, a settling foundation, or uneven spring tension. New weatherstripping will mask a small gap, but if it's noticeable, it's better to have the door's balance and track alignment checked rather than just packing in more rubber.
Will sealing the gaps keep mice and bugs out of my garage?
Yes, a tight bottom seal plus a threshold seal is one of the best ways to stop mice, insects, and leaves, since the gap under the door is their easiest way in. Mice can squeeze through a quarter-inch space, so make sure the bottom seal makes full contact with no gaps at the corners, which is where pests most often slip through.
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