Influence of Gap Sizes Around Swinging Doors with Builders Hardware on Fire and Smoke Development

Fire Protection Research Foundation report: “Influence of Gap Sizes around Swinging Doors with Builders Hardware on Fire and Smoke Development”
Authors:Drew Martin and Brian McLaughlin, P.E.
Date of issue: March 2018

Influence of Gap Sizes Around Swinging Doors with Builders Hardware on Fire and Smoke Development

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This study was conducted, in part, to assist standards writers with the information necessary to establish the effective maximum gap sizes for wood and steel fire doors.

Swinging fire doors with builders hardware are critical components of maintaining building compartmentation. The ability for Swinging Doors with Builders Hardware (Chapter 6, NFPA 80) to restrict fire and smoke is determined by meeting the requirements in Chapter 6 of NFPA 80, Standard for Fire Doors and Other Opening Protectives (2016) and passing the NFPA 252, Standard Methods of Fire Tests of Door Assemblies (2015) standardized fire door test. The ability for swinging fire doors to resist the passage of fire and smoke and to comply with the applicable standards is affected by the gap sizes around the perimeter of the door, and as a result, the maximum allowable gaps around swinging fire doors are codified.

While the gap sizes identified in NFPA 80 have been written into the codes and standards for more than 50 years, recent requirements written to improve inspections, testing, and maintenance (ITM) have resulted in door clearance issues being one of the most frequently cited deficiencies. NFPA 80 currently allows a maximum bottom gap of 3/4 in. and a maximum of 1/8 in. for the perimeter (e.g. along vertical and top edges) of the swinging fire doors (with an additional 1/16 in. over-tolerance for steel doors). The clearance under swinging fire doors is frequently found to be greater than the maximum allowable gap size currently allowed by NFPA 80, due to irregularities in flatness and levelness of concrete slab floors at and around door openings.

The difficulty in achieving the 3/4 in. bottom gap instigates the question at the heart of this research, of what effect increasing the maximum allowable bottom gap size has on fire development.

Fire Door Experimental Testing to Study the Influence of Door Gaps Around Swinging Fire Doors

Fire Protection Research Foundation report: “Fire Door Experimental Testing to Study the Influence of Door Gaps Around Swinging Fire Doors"
Authors: Lawrence Gibson, P.Eng., Scott Leduc, B.A. Sc., Mike van Geyn, A.Sc.T., QAI Laboratories
Date of issue: May 2022

Fire Door Experimental Testing to Study the Influence of Door Gaps Around Swinging Fire Doors

The project goal was to determine through experimental testing the effect that door clearances might have on the performance of a fire door assembly. Single swing and double egress pair doors were evaluated, for steel and composite doors with fire protection rating up to 90 mins and wood doors rated for 20 mins. Generic full-scale fire door testing with door assemblies having sill clearance requirements set at 3/4” (19 mm) (the current maximum allowable gap in NFPA 80) and at an increased gap of 1” (25 mm) were conducted so that the effects of increased sill gaps could be evaluated.