Door astragals are typically used to cover the gap between pairs of doors. Thus, the astragal closes the clearance gap. The astragal closes the clearance gap for the purpose of either providing a weather seal, ensuring privacy, preventing sound from leaking in or out of a room, minimizing the passage of light between the doors, or retarding the passage of smoke or flame during a fire.
Astragals can also used between the top and bottom leaf of a dutch door, and between the top and bottom doors of a tall unit. Usually the astragal is mounted to the pull side of the active door.
Astragals are provided loose, for field mounting, with screws provided by the installer.
When required, for a nominal fee, the astragals can be factory welded to the door.