Horizontal sliding-door Systems: Opening New Opportunities for Design Flexibility

Since 2000, Fire and Building Codes Allow sliding-door systems for Emergency Egress
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Anthony Flint

The Sliding Door and Codes

The standards strictly limited the use of horizontal sliding doors. These systems could not, for example, be the primary means of egress. Any horizontal sliding-doorsystem that separated internal spaces also had to meet tough requirements for fire resistance. The distinction between a fixed wall and a door was that flammable objects could be stored next to a wall, but not in the way of a swinging door; moveable partitions fell into a kind of no-man's land between the two.

Horizontal sliding-doortechnology grew out of a desire to create a high acoustically rated folding partition which would produce sound transmission ratings comparable to insulated walls. In the early 1960s, early models where developed that used a two-track folding partition system that consisted of two walls of steel independently suspended from overhead tracks and a six-inch dead air space. But while built with acoustics in mind, the horizontal sliding door was also capable of resisting fire.

In the 1970s, the horizontal sliding door passed the two major fire testing methods for door assemblies to withstand the passage of fire, holding up in intense heat rising to 1,700 degrees Fahrenheit and maintaining structural integrity. In 1986, the National Fire Protection Association committee that writes the Standard for Fire Doors and Windows first considered the introduction of a new chapter for the installation of special-purpose horizontally sliding accordion or folding doors. A few years later, the NFPA committee that writes the Means of Egress section considered a recommendation to permit the use of certain horizontal sliding doors as a means of egress in selected applications-to protect elevator lobbies, in buildings where the occupant loads were less than 50, and as fire and smoke barriers in healthcare facilities.

Sliding doors had been previously accepted for elevator lobbies, and the committee also determined that doors that slide horizontally did not present any more of a problem than swinging doors that open against the direction of travel-the latter deemed acceptable for buildings serving occupant loads of less than 50. Finally, horizontal sliding doors served as effective smoke barriers, which were required under the code for health care facilities virtually every 75 feet, to facilitate the "defend in place" approach used with occupants with special needs in fire emergencies. All of these proposed changes appeared in the 1988 edition of the Life Safety Code, and the three regional model building codes subsequently adopted them as well. The horizontal sliding door was thus acceptable as an alternative to traditional swinging doors in selected instances.

The Final Push

In 2000, the three regional building code entities merged into a single group that produced a single national uniform code-the International Building Code. Around the same time, the horizontal sliding door had a final breakthrough: an acceptable means of egress in all applications, regardless of occupancy loads, except for storage areas for flammable materials. The National Fire Protection Association changed its code as well, essentially to reflect what was in the IBC.

A chief characteristic that convinced the code writers was that the sliding-door systems could actually be easier to get through in an emergency than conventional swinging doors, while providing an effective barrier for fire and smoke, and serving as a key segregating device in other security emergencies.

"The burden of proof is high. The industry is reactive to cataclysmic events," said Tim Welch, vice president of marketing at Won-door, based in Salt Lake City, Utah. "We did a lot of education and showed that these systems were reliable, electronically supervised, and functioned well for egress. So over about 15 years, it's been mainstreamed. There are no restrictions on use. They can be used in any occupancy. This is all very new to enforcement professionals and design professionals."

 

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Originally published in Architectural Record.
Originally published in December 2005

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