NFPA 80 – Standard for Fire Doors & Other Opening Protectives no longer includes a prescriptive requirement for certain pairs of fire doors to have astragals. In the 1999 edition of this standard (and prior editions), an overlapping astragal was required for pairs of doors rated for more than 1 1/2 hours. In the 2007 edition, the requirement for an overlapping astragal was removed, and the use of the astragal is dependent on the manufacturer’s listing procedures. If a jurisdiction has adopted a code which references the 2007 edition of NFPA 80 or a later edition, check with your door manufacturer to see if an astragal is required.
When an overlapping astragal is used, pairs typically have either automatic flush bolts and a lockset, or mortise fire exit hardware on one leaf and vertical rod fire exit hardware on the other. These applications also require a coordinator to ensure that the doors close in the proper sequence. The reason the mortise x vertical rod application was commonly used on 3-hour pairs was to avoid the overlapping astragal causing an egress restriction. If two vertical rod devices are used with an overlapping astragal, one door would not be available for egress unless the other door was opened first. NFPA 80 prohibits egress doors from having an overlapping astragal that restricts the free use of either leaf.
NFPA 80 defines two types of astragals – overlapping astragals and split astragals. Split astragals are also called meeting stile gasketing. NFPA 80 states that pairs of doors which require astragals must have at least one attached in place which projects approximately 3/4-inch, but this is dependent upon the manufacturer’s listings. Many door manufacturers do not require astragals for most of their fire-rated pairs, although gasketing may be required at the meeting stiles to reduce air/smoke infiltration. Astragals or meeting stile gasketing may also be used for other purposes, such as weather, sound, or light.
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