How to Replace the Gasket on a Bottom Exterior Door

Written by lee carroll
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How to Replace the Gasket on a Bottom Exterior Door
Replace your door sweep to help keep cold, winter air outside. (Steve Mason/Photodisc/Getty Images)

Many exterior doors have a gasket, called a door sweep, across the bottom to help seal the doorway. Flat styles fit across the bottom face of the door on the interior side, unless the door swings outward. In that case, the sweep belongs on the outside. U-shaped sweeps fit like a cap over the interior and exterior bottom edges of the door. Replace your gasket with another of the same style.

Skill level:
Moderately Easy

Things you need

  • Screwdriver
  • Measuring tape
  • Marker
  • Metal shears
  • Metal file or rasp
  • Utility knife

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  1. 1

    Remove the screws from the existing door sweep. If the sweep is flat, it will fall off when you remove the screws. If it is U-shaped, open the door and slide off the sweep. Take the old sweep with you to purchase a new one. Choose a replacement with screw holes that match up with the holes in the old one.

  2. 2

    Measure across the bottom of the door. Transfer that measurement to the new door sweep and make a mark with a marker. Cut the metal strip of a flat sweep at the mark with metal shears. Complete the cut through the rubber fin at the bottom of the strip with a sharp utility knife. Cut a U-shaped sweep to the correct length with metal shears. Rub a metal file or rasp along the cut metal to dull any sharp edges.

  3. 3

    Align the screw holes of a flat sweep with the holes in the door and insert one screw through any hole on the strip. Twist the screw clockwise by hand. Insert the remaining screws loosely with the screwdriver. Open and close the door. If the rubber fin touches the threshold but does not get caught on it, tighten the screws on the sweep.

  4. 4

    Open the door and slide a U-shaped door sweep onto the bottom of the door to install it. Align the screw holes and insert the screws loosely. Close the door to check the fit. Slide the sweep up or down to adjust it. Trimming the short fins of a U-shaped sweep is not advisable.

  5. 5

    Adjust a flat sweep if it prevents the door from moving properly. Slide it up or down to adjust it then tighten the screws to hold it in place. If adjusting does not help shorten it, remove the sweep. Trim a small amount of rubber off the bottom of the fin with the utility knife then reinstall the sweep.

Tips and warnings

  • If you cannot adjust your U-shaped door sweep correctly, install an adjusting threshold that can be raised and lowered.
  • If the weatherstripping around the door frame is cracked, install a new one when you install the new door sweep.
  • Drilling new holes to fit an odd-shaped sweep can weaken the door and reduce its insulating ability.

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