Sealing a Threshold

  • 1-3 hours
  • Intermediate
  • 15-50
What You'll Need
Tape measure
Sharp scissors
Threshold strip

Sealing your threshold after installing it is important to prevent moisture and water from entering under the door, damaging the floor and nearby items. While sealing a threshold isn't difficult, you will want to do it properly to ensure that a strong seal is formed.

Step 1: Take Measurements

You will want to measure the gap in between the bottom of the door and the floor. Also get measurements for the width and the length of the space. These numbers need to be very accurate to prevent the door seal for the threshold from being off. Even the tiniest gap in measuring can cause the entire threshold to be ineffective.

Step 2: Buy New Threshold and Seal

With the measurements in hand you can purchase your new threshold strip. A lumber yard will cut a new piece to fit, or you can find new thresholds in standard sizes at any home improvement store. You will need to decide if you want a wood or a metal threshold. A metal threshold may not look as nice, but will provide a better seal from the elements. Wood is vulnerable to water damage that you might not see right away.

Step 3: Remove Old Threshold

First remove the old threshold from the floor. You should see several screws set into the strip. Unscrew these and use a pry bar to pull the whole strip off. You will also want to remove the rubber weather-stripping if it’s been installed.

Step 4: Mark for Placement

With the old seal removed, you can start to make your marks on the floor where the new threshold will go. Use the hacksaw to cut the strip if necessary. Scissors will cut through the weather stripper to size.

Lay the threshold down on the marks and drill pilot holes. You may be able to use the holes from the old material.

Step 5: Install the Strip

Install the strip making sure it’s secure. Attach the weather strip to the center of the threshold. Use a thin layer of silicone caulk to help form a tighter seal. The caulk will need to be applied to both the underside of the threshold and the underside of the weather strip material. Allow plenty of time for the caulk to dry before you test the door. If you knock it out of place before the caulk has dried, you will break the seal and may not know about it until the next rain.

Step 6: Test the Fit

After you’ve allowed time for the caulk to cure, go back and test to make sure the door opens and closes with no drag. If you took care in your measurements, this shouldn’t be a problem.

You’ve just created a seal for your threshold that will keep the elements outdoors where they belong. This will protect your door, your floor, your porch and any items you have placed in the doorway area.