How to Install a Garage Door Threshold Seal on the Floor
To install a garage door threshold seal, clean and dry the concrete where the door meets the floor, dry-fit the rubber threshold strip to length, then bond it down with the manufacturer's adhesive while the door is open. Most homeowners can knock this out in about an hour, and you'll want to let the adhesive cure before driving over it. The threshold seals against the floor (not the door), so it stops rain, leaves, dust, and the occasional curious bug from sneaking under the bottom of your garage door.
Step by step
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1
Measure your opening and buy the right threshold
Measure the width of your garage door opening at the floor and add a few inches of wiggle room. Standard single doors run about 9 feet and doubles about 16 feet, but measure yours to be sure. Pick a threshold profile sized for your gap: a low, wide profile for small gaps, or a taller center bead if you're fighting water that pools at the door. Buy the matching adhesive too (many kits include it, but some sell it separately).
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2
Clean and dry the concrete thoroughly
Open the door fully so you have room to work. Sweep the contact area, then scrub the concrete with a stiff brush and a degreaser or simple soap-and-water to lift oil, dust, and tire residue. Adhesive will not stick to a dirty or oily slab, so this step makes or breaks the job. Rinse, then let it dry completely. If your garage floor is sealed or painted, lightly scuff the strip where the seal will sit so the adhesive can grab.
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3
Dry-fit and trim the threshold to length
Lay the threshold strip in place with the door open and the door fully resting on top of it where it will close. Mark your length and cut it with a utility knife or hacksaw. Then lower the door by hand (or close it) and trace a pencil or chalk line along both edges of the strip onto the floor so you know exactly where to spread adhesive. Re-open the door.
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4
Apply the adhesive and press the seal down
Run a generous zig-zag bead of the supplied adhesive on the concrete between your two guide lines, then set the threshold into the wet adhesive and press it firmly along its whole length. Smooth out any bow or wave so it sits flat. Wipe up squeeze-out right away with a rag before it skins over.
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5
Weight it down and close the door to set the seal
Lay boards and something heavy (bricks, paint cans, a bag of sand) along the threshold to hold it tight to the floor while the adhesive grabs. Then close the door so the bottom rubber rests on the new threshold and forms its seal shape. Check that the door's weatherstrip meets the threshold evenly across the whole width with no daylight.
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6
Let it cure before driving on it
Leave the weights in place and keep the door closed for the full cure time on the adhesive label, usually 24 to 48 hours. Don't drive over the threshold or hose down the floor during that window. Once cured, pull the weights, do a final water test with a hose if you're sealing against rain, and you're done.
When to call a pro
Call a pro if water keeps coming in after a properly installed threshold, if your concrete floor is badly cracked, pitted, or uneven (the seal needs a flat surface to work), or if the gap under your door is uneven side to side, which usually points to a door that's off its tracks or a sagging slab that needs real attention.
Call (888) 290-7421Frequently asked
What's the difference between a threshold seal and a bottom seal?
A bottom seal (also called a door sweep or astragal) attaches to the bottom edge of the door itself and moves with it. A threshold seal bonds to the garage floor and stays put. They do the same job from opposite sides, and for a stubborn gap you can actually use both together for the tightest seal against water and pests.
How do I keep water from pooling at my garage door?
A taller center-bead threshold creates a small dam that blocks water from running in under the door, which is your best bet for a driveway that slopes toward the garage. Just know a threshold holds water back at the door but won't move standing water that's already inside, so pair it with good drainage outside if pooling is severe.
Will a threshold seal interfere with closing or opening the door?
No. The threshold sits flat on the floor and only contacts the rubber on the bottom of the door when it's fully closed, so it doesn't affect the opener, springs, or travel. The one thing to watch is choosing a profile that matches your gap. Too tall and the door's auto-reverse safety may sense resistance, so test the door a few times after install.
How long does a garage door threshold seal last?
A good rubber or vinyl threshold typically lasts 5 to 10 years, sometimes longer in a sheltered garage. It wears faster if you regularly drive over it or park with hot tires sitting on it. Once it cracks, flattens, or peels up at the edges, scrape off the old adhesive, clean the slab, and re-bond a fresh strip.
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