Moisture Sealing Practices for an Exterior Door

Finishing the Door

• Most doors come prefinished, but a worn or unfinished wood door needs to be properly sealed to prevent moisture from damaging it. Staining and sealing the wood with a clear sealant works well, states Simpson Doors, or use a latex or oil-based paint. No part of the wood should be left unsealed, even if that part won't be exposed to the exterior of the home.

Sealing Cracks

• Cracks develop around door frames as houses age. These small crevices allow moisture to seep into the home and damage the wall. Wall-based foam sealant fills these cracks and creates a strong moisture barrier, according to the U.S. Department of Energy. Silicone caulk works better if the cracks or gaps are between a wood door frame and brick or concrete walls.

Weather Stripping

• Weather stripping consists of a thin layer of material that lines the door frame of an exterior door. This creates a barrier that stops water from leaking in and air from leaking out. While materials like metal and hard plastic are more durable, foam and other compressible strips block water the best, states the U.S. Department of Energy. The tight seal created by a compressed weather strip stops water from coming in around a door.

Flashing

• Flashing around an exterior door includes the installation of special metal sheeting around the door frame to keep water from soaking into the wall. The rest of the house is covered in plastic house wrap to protect the underlying wood. This wrap has to be cut around doors and windows, and installing flashing adds a protection cap around these openings.

Corner Pads

• On some exterior doors the vertical lines of weather stripping material create a suction that draws water into the home. Adding the small foam squares known as corner caps prevents this. The adhesive foam blocks feature two ridges that fit tightly together when the door is closed, cutting off any moisture from reaching the weather stripping.