Replace a Garage Door Bottom Seal

Cold air whistling under your garage door signals a worn bottom seal. That rubber strip wedged into the door's lower edge does more than keep out drafts — it blocks rain, dust, leaves, and the occasional determined mouse. A fresh seal takes thirty minutes and costs less than takeout. The work is straightforward: pull out the old rubber, clean the metal channel, slide in the new. You'll feel the difference the first cold morning when your garage stays ten degrees warmer and the concrete stays dry after a storm.

1. Measure and order the correct seal. Open the door fully so it's horizontal. Measure the exact width of the door from edge to edge. Order a seal type that matches your door's retainer style — most use either a T-shaped bulb seal or a flat bead seal with a vinyl insert channel. Buy it two inches longer than your measurement to ensure full coverage.
2. Remove the old seal. With the door closed, grip the seal at one end and pull it straight out of the metal retainer track along the door's bottom. If it's stuck, use pliers to grip and work it back and forth while pulling. Some seals have a vinyl insert spine — pull the rubber bulb away first, then extract the hard spine separately from its slot.
3. Clean the retainer channel. Use a wire brush or stiff nylon brush to scrub out the metal track where the seal sat. Remove all dirt, old rubber fragments, and debris. Wipe the channel with a damp rag, then dry it completely. Check for rust or damage — light rust is fine, but deep corrosion means the channel may need replacement.
4. Cut the new seal to length. Lay the new seal on the ground and measure it against your door width. Mark it two inches longer than the door, then cut straight across with a utility knife or heavy scissors. The extra length ensures the seal reaches both edges fully even after compression.
5. Feed the seal into the channel. Start at one end of the door with the door closed. Push the seal's rigid spine or T-shaped top into the metal retainer track, then work along the door's width, feeding the seal in gradually. Apply even pressure and keep the seal straight. If it binds, spray a light mist of soapy water into the channel as lubricant.
6. Trim the excess and check the fit. Once the seal is fully seated, trim the excess at both ends so it's flush with the door edges. Open and close the door twice to verify the seal compresses evenly against the floor along the entire width. The rubber bulb should flatten slightly when the door is closed but not fold over or buckle.
7. Adjust door closure if needed. If the new seal prevents the door from closing fully, adjust the down-limit on your garage door opener. Locate the limit adjustment screws on the opener motor unit and turn the down-limit screw counterclockwise a quarter-turn at a time until the door seats properly against the seal without reversing.
8. Test the seal's effectiveness. Close the door and walk the perimeter inside, looking for light gaps. On a windy day, you'll feel air leaks immediately. Run your hand along the seal's length while someone stands outside with a flashlight shining under the door — any light means the seal isn't compressing properly at that spot.