Door designs should provide a flush surface that will allow properly selected interior locking hardware to be mounted without gaps between exit device crossbars or traditional push bars on doors with full view glass kits or recessed panels in pairs of doors. There are certainly other door design aspects when considering a “security door assembly” but this writing is focused only on the “chain resistant” aspect of door design.
Door hardware will be selected for the interior as well as exterior of the door opening. Once again with “chain resistance” being the objective, the use of rim exit devices or concealed rod exit devices allow for meeting life safety egress codes as well as the “chain resistant” criteria. Surface vertical rod exit devices should not be used as they provide a gap between the door surface and the vertical rods extending to the top and bottom latches. These devices will satisfy the life safety egress codes but not the “chain resistant” criteria. Some panic devices, (for selected brands) allow for easy field upgrades with electrical latch retraction kits if the need arises to upgrade an opening that was not specified for electrical access at creation.
Exterior door hardware that achieves the desired “chain resistant” status will consist of a flush mounted, recess designed, full sized pull, in lieu of traditional levers or offset pulls. Pull design prevents the use of a chain or cable device to prevent doors from opening. Desired features for the “chain resistant” flush pull would be a fully serviceable flush pull handle that could be used in hollow metal, aluminum storefront, and wood doors applications. The pull should not be an integral part of the door fabrication as this creates a very unfriendly and costly service situation over the life of the opening. National Security and Door was unable to locate an acceptable pull that would meet the desired features. We developed and have since received a patent pending status for a heavy duty stainless steel pull that meets all of the basic and desired features needed to produce a serviceable “chain resistant” exterior pull application for all door compositions and designs.
Use of the “chain resistant” flush pull will allow for ingress through either door of a pair when the latching device has been unlocked mechanically or electrically. We see openings being designed with only one traditional exterior trim to create the “chain resistant” effect. Even in an unlocked state as there is no means to pull the door open, cutting the ingress capability of the opening in half. This hardware arrangement will maintain the life safety egress requirements and may be acceptable for low volume pedestrian traffic but is not a best case application with the availability of the “chain resistant” flush pull.
National Security and Door Corp. Security Innovation and Design
Phone: 804-745-4936 | www.nsandd.com