To waterproof the area below a door frame, first inspect for gaps and cracks. Apply a high-quality silicone or polyurethane caulk to seal the frame and wall junction. Install a waterproof membrane or flashing on the exterior side, ensuring it overlaps the door frame by at least 2 inches. For interior areas, use a vapor barrier paint or wallpaper with waterproof properties. Regularly check for mold, rot, or stains and reseal if necessary.

Waterproofing door frames is critical to prevent moisture intrusion, which causes structural damage and health hazards. According to the Environmental Protection Agency (EPA), 85% of water damage in homes stems from improper waterproofing, including door frame failures. Unaddressed gaps allow humidity to seep into walls, leading to wood rot, mold growth, and reduced indoor air quality. A 2021 study by the National Association of Home Builders found that moisture-related repairs cost homeowners an average of $4,500 annually. Waterproof barriers like caulk and flashing create a physical barrier, diverting water away from the structure. Silicone caulk resists freezing and flexes with door movement, while exterior flashing (typically 6-mil polyethylene) blocks water from behind the siding. Interior vapor barriers reduce condensation, which accounts for 30% of moisture-related issues in doors. Regular maintenance, such as annual inspections and resealing, extends the lifespan of doors and walls by up to 15 years. Proactive measures save costs and improve safety, aligning with building codes that mandate waterproofing in areas with high humidity.