How to Seal an Exterior Door

  • 1-2 hours
  • Beginner
  • 20-60
What You'll Need
Measuring tape
Self-adhesive foam weatherstripping

An Exterior Door has a number of functions; in addition being a point of entry and exit, it can provide illumination and ventilation as well. These additional functions can also contribute to high amounts of unwanted air leakage and associated energy loss. Cracks around an exterior door and water leaking through it can cause considerable damage to the door trim, tile, carpet, floor and walls. Sealing an exterior door to prevent water from coming in is fairly easy and it also will improve your home’s energy efficiency.

Sealing an exterior door is fairly easy with the proper tools. Most of the tools and materials you’ll need may even already be in your home.

Step 1 - Find and Fix Leakages

Examine where the leaks are specifically located before sealing the door; incoming light around the door is one way to identify leak locations. Water can get in anywhere air can; check for hidden leaks by using a piece of thread. Drape some thread on your fingers and allow it to hang in front of the door’s cracks near the edges. Move your hand gradually around the door’s full border and note down where the breeze is entering by checking the thread’s movement.

Step 2 – Measuring the Sides of the Door Frame and Cutting Weatherstripping

The top and sides of the door frame must be measured carefully to ensure a good fit. Cut each part of self-adhesive foam weatherstripping in one piece-one for the top and one for the two sides. If you fail to measure the frame properly, you may need two pieces or more on one side; using multiple pieces along one side will prevent the door from being sealed properly since leaks may not be adequately blocked.

Weatherstripping that’s damaged or weak can significantly raise energy loss around an exterior door. It should be checked annually and changed if needed. The hinge screws should also be checked and tightened. The door seal should be inspected for a tight fit after changing the weatherstripping. If it does not seal properly on the sides or if it’s too tight making the door difficult to close and lock, the weatherstripping may need to be adjusted. If weather stripping adjusting doesn’t help, it may be time to consider changing the exterior door.

Step 3 – Measuring Door Width and Cutting Door Sweep Weatherstripping

Get the exact length of the door from the bottom and cut door sweep weather stripping to that same size. Door sweep weatherstripping fastens immediately to the door by a metal groove that glides to the door’s bottom. It will be easy to screw the sweep to the door since the groove comes pre-drilled on sweep weatherstripping. Just make sure that the door is closed when you screw it on.

Step 4 - Check for Leaks

Check for air or light that enters through the door’s corners using the techniques in the first step. If air or light can still enter then you must have sealed it incorrectly.

You can purchase replacement weatherstripping to seal an exterior door at many hardware stores. They come is a wide selection of materials such as felt, foam rubber, bent metal, plastic and EPDM rubber. The materials durability should be an important thing to consider when choosing weatherstripping.