An astragal is a molding or strip designed to close gaps in door openings. Astragals may cover the space between a pair of doors, between the top of a door and a flush transom panel where no mullion is present, or between the top and bottom leaves of a Dutch door. For fire-rated Dutch doors, astragals are required to ensure simultaneous closure of both the upper and lower leaves. Astragals may also be specified for single doors, where they overlap the frame face to enhance security.
Astragals determine whether both door leaves can be active simultaneously or must be operated in a specific sequence. They also enhance privacy, provide protection against certain weather conditions, and reduce the transmission of light, sound, smoke, flames, and gas, which is critical during fire events. While the NFPA 80, Standard for Fire Doors and Other Opening Protectives, does not mandate astragals for fire-rated doors, some manufacturers may require them to comply with fire door listings. Additionally, model building codes may require astragals at specific pairs of doors within a building, even for non-fire-rated doors.
Types of Astragals
Two primary types of astragals are used in various applications, and specific circumstances may require one over the other.
- Overlapping Astragals
- Split Astragals
Overlapping Astragals
An overlapping astragal consists of a solid piece of steel, aluminum, wood, or another material attached to one door leaf to cover the gap, often with gasketing. On pairs of doors, overlapping astragals prevent both doors from being open simultaneously; one door must be opened before the other, and a proper closure sequence is required for complete security. A coordinator is necessary for self-closing, same-swing pairs with overlapping astragals to ensure the correct closing order. In Dutch doors, the astragal functions as a coordinator.
Overlapping astragals prevent both leaves from being active; they are not suitable for push/pull pairs or openings with vertical rod exit devices on both leaves. Model building codes also prohibit overlapping astragals on doors with active/inactive hardware located within a means of egress. When both doors are self-closing, and an overlapping astragal is used, automatic flush bolts are recommended if the active leaf has a lockset. If the active leaf requires panic or fire exit hardware, two configurations are possible: installing a mortise exit device on one door and a vertical rod exit device with a coordinator on the other, or installing a vertical rod exit device on one door and an open back strike on the other.
Overlapping astragals provide enhanced security. When installed on the exterior of the active leaf, they cover the gap between doors on the secure side, reducing the risk of tampering with the latch bolt that secures both leaves.
Split (Meeting) Astragals
A split astragal, also known as meeting stile gasketing, consists of two pieces, each attached to one leaf of the door pair. The gasketing meets in the center, covering the gap to create a seamless appearance. Because each door has its own astragal component and only gasketing covers the gap, both leaves can remain active and do not require a specific opening or closing sequence unless dictated by other hardware. For applications where both door leaves must remain active, such as push/pull pairs or openings with vertical rod exit devices on both leaves, a split astragal is recommended.
Doors, Frames, Hardware & More
When choosing the right astragal for your commercial opening, it’s important to consider security and how and where the doors will be utilized. Overlapping astragals require more coordination but offer increased security, and split astragals may allow both leaves to remain active. Contact one of our experts today to learn about all the ways LaForce can help you with your next project.
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