A thin, flexible barrier typically made of metal and rubber, or other polymers, is affixed to the edges of a door frame to seal the gap between the door and the frame. This barrier effectively prevents air, water, and insects from entering a building. For example, these barriers often include a fin or bulb-shaped section designed to compress against the door, creating a tight seal.
Such barriers are crucial for maintaining comfortable indoor temperatures, reducing energy consumption, and preventing damage from moisture and pests. By minimizing drafts, they contribute significantly to energy efficiency by reducing the load on heating and cooling systems. Historically, simpler materials like felt or foam were used, but modern materials offer superior durability, resistance to weathering, and improved sealing capabilities. This evolution reflects the increasing demands for energy-efficient buildings and comfortable living spaces.