Register to attend the free Research Foundation webinar on “Influence of Door Gap Sizes Around and Under Swinging Fire Doors”

The Fire Protection Research Foundation, the research affiliate of NFPA®, will be hosting a webinar on September 15th that will present the findings from a recently completed experimental testing research study on “Influence of Door Gap Sizes Around and Under Swinging Fire Doors.” Register here to attend this free webinar. Fire doors have one job: to prevent a fire from spreading. For fire doors to perform their job, clearance gaps around and under swinging fire doors must resist the passage of smoke, gases, and flames. Fire development, smoke movement, and the ability of the fire door to meet the test standards are affected by the gap sizes around the perimeter of the door, within the frame, and between the bottom of the door and floor. Hence, these gap sizes are regulated. The current requirements for door clearances in NFPA 80, Standard for Fire Doors and Other Opening Protectives, are from information and data gathered several years ago. Door clearances are one of the most frequently cited deficiencies on swinging doors with builders hardware due to irregularities in flatness and levelness of concrete slab floors at and around door openings. To gain a deeper understanding of the impact of gap sizes on fire development and smoke movement, the FPRF undertook a research study. The goal of this phase of the research project was to determine, through experimental full-scale testing, the effect and influences clearance gap dimensions under swinging fire doors have on the performance of the assemblies to prevent a fire from spreading. 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 was conducted with door assemblies having sill clearance requirements set at ¾” (19 mm) (the current maximum allowable gap in NFPA 80) and at an increased gap of 1” (25 mm) so that the effects of increased sill gaps could be evaluated. Additionally, one test was conducted with sill clearance dimensions ¼” (6 mm) as per NFPA 252, Standard Methods of Fire Tests of Door Assemblies. The acceptance criteria as specified in NFPA 252 were used to evaluate the experimental tests in this project. It was observed that only the double egress pair of steel doors tested with ¾” (19 mm) bottom gap dimensions met the acceptance criteria. The tests generally showed that larger gaps increase airflow rate and may make it more challenging to meet the acceptance criteria. Significant increase in air flow rate was observed when the sill clearance was increased from ¾” (19 mm) to 1” (25 mm). Wood and composite doors seem to be more impacted with flaming and burn through of doors observed sooner for doors with 1” (25 mm) sill clearance than for ¾” (19 mm). Total of 17 fire door assemblies were tested in this project and it is important to note that it represents only a very small sampling of swinging fire door assemblies. The door assembly components used in experimental tests were of known quality and had successfully passed fire door testing for the ratings (when intumescent materials were used for wood and composite doors tested under positive pressure). However, the experimental testing conducted in this study introduced non-standard conditions — door gap dimensions larger than those allowed in the fire door test standards (NFPA 252). The tests were representative of how older existing swinging fire door assemblies—those fire door assemblies tested under neutral pressure conditions—might perform when door gap clearances exceeded NFPA 80’s specifications. One reason for this testing method is that many older existing swinging fire doors have excessive door gap clearance dimensions because of poor installation and maintenance practices. The majority of these older existing swinging fire doors do not have built-in intumescent materials like their modern-day counterparts tested under positive pressure fire conditions. It is generally accepted that intumescent gasketing materials mitigate large door gap clearance dimensions by sealing the spaces between door leaves and door frames when exposed to elevated temperatures. However, since older existing swinging fire doors were not required to have intumescent gasketing materials, it is uncertain whether excessive door gap dimensions might impact their ability to perform as designed. The final report from this research study is available from the FPRF website. The webinar will review the results and observations from this experimental research along with the existing guidance of clearance sizes of door gaps around fire doors. Mike van Geyn, QAI Laboratories and Keith Pardoe, Pardoe Consulting, will lead this webinar discussion. Registration is free and required to attend. Visit www.nfpa.org/webinars for more upcoming FPRF webinars and watch on-demand archived research webinars.This webinar is supported by the Research Foundation 2022 Webinar Series Sponsors: American Wood Council, AXA XL Risk Consulting, FM Global, Reliable Automatic Sprinkler Co., Inc., Telgian Engineering and Consulting, The Zurich Services Corporation. The Research Foundation is celebrating its 40th year in existence in 2022. Learn more about this noteworthy milestone.