This type of weather seal utilizes a small, sawed groove (a kerf) in the door jamb or stop molding. A flexible fin or bulb, integrated with the weather strip, inserts into this groove, creating a tight seal against air and moisture infiltration. This design offers a cleaner, less obtrusive appearance compared to surface-mounted alternatives. An example would be a thin strip of vinyl or rubber with a protruding fin designed to fit snugly within a precisely cut channel.
Incorporating this sealing method provides significant advantages in enhancing energy efficiency by reducing drafts and heat loss. It also contributes to improved sound insulation and protection against dust and insects. Historically, this approach has evolved from simpler methods of sealing gaps, offering a more durable and effective solution compared to felt or foam strips. Its concealed nature makes it aesthetically preferable in many architectural styles.