Jamb Seal

A jamb seal is a strip of flexible material—typically vinyl, rubber, or a combination of a rigid wood or aluminum retainer with a flexible bulb or blade—mounted along the face of each side jamb of a garage door opening. It runs vertically from the floor to the top corner and creates a compressible barrier that the closed door presses against, sealing the vertical gap between the door's edge and the jamb framing.

Jamb seals are part of the door's complete perimeter seal system, which also includes the astragal at the bottom and weatherstripping across the top. Of the three, the side jamb seals are often the least visible but are important for preventing wind-driven rain from entering along the sides of the door—a common failure point on doors with warped sections or that are not plumb in their opening.

Jamb seal profiles vary. The most common residential style is a vinyl stop with an integral flexible fin or bulb that deflects as the door closes. Commercial and higher-performance doors use larger profiles with compression seals that maintain contact even if the door is slightly out of plumb. Brush seals are used in some commercial applications where the door surface is not flat.

Jamb seals are consumable parts. Sun, temperature cycling, and repeated compression cause the flexible element to harden and crack over time, at which point the seal no longer conforms to the door surface. A damaged jamb seal shows as visible light or wind noise along the door's side edges. Replacement is a straightforward task—the old seal is removed and a new strip is nailed or screwed to the jamb face.