A barrier installed at the bottom of a door, designed to seal the gap between the door and the floor, effectively preventing drafts, moisture, insects, and debris from entering a building. This barrier is typically made from materials like rubber, foam, silicone, felt, or metal. Different types exist, including door sweeps, automatic door bottoms, and threshold seals, each tailored to specific door types and threshold configurations. A properly fitted seal creates a tight closure when the door is shut.
Effective sealing of this gap offers significant advantages. Lower energy bills result from reduced air leakage, keeping heated or cooled air inside. Improved indoor air quality is achieved by minimizing the entry of pollen, dust, and other airborne particles. Protection against moisture damage is another key benefit, preventing rot, mold, and mildew growth. Historically, simple materials like rags or felt were used for this purpose. Modern materials and designs offer significantly improved performance and durability, providing a more reliable and long-lasting solution for an age-old problem.