Any smoke and draft control assembly must be less than the UL 1784 air leakage performance standard of three cfm/sq. ft before it can be specified onto a project. The UL 1784 test typically allows for the undercut of a swing door to be taped closed. However, under exception 3, the code specifically requires that the undercut on swing doors used as an additional door not be taped during this test. The pressure differential that can exist at the shaft paired with the space between the undercut of the door and the floor can allow smoke to migrate from one side of the barrier to the other at a much faster rate than 3 cfm/sq. ft. Avoid specifying a product that may leak excessively at the elevator shaft by either verifying that the door has a drop seal in place or has been tested in an elevator shaft scenario or without the undercut taped.

An accordion door is another type of smoke barrier that may perform differently in a pressurized environment than the UL 1784 test environment. Accordion doors use a rubber skirt to create a smoke resistant seal between the large steel accordion door and the floor. In a large pressurized space where a smoke control system may be used, the air pressure can exert a considerable force upon the broad curtain surface pushing or pulling the door out of place or causing it to swing. Either way, the seal at the bottom of the door can lift away from the floor enabling significant amounts of smoke to breach the barrier.

Rolling magnetic gasketing systems achieve an UL 1784-tested air leakage rate ranging between 0.33 and 0.6 cfm/sf of door opening. These air leakage rates are so low that the UL 1784 testing procedures had to be modified to be able to accurately measure the air leakage of this system. Additionally, these products are designed to operate at the elevator shaft and the performance of these systems is unaffected by pressurized environments. Tom Allen, the inventor of rolling magnetic gasketing systems and founder of Smoke Guard, was a practicing commercial architect who wanted to provide a better barrier against smoke migration than what was currently available on the market. "If there is hazardous air on one side of a barrier that you don't want on the other side and you don't want a wall there all of the time, nothing prevents smoke migration better than a rolling magnetic gasketing system," explained Mr. Allen.

While elevator pressurization systems are designed to prevent the migration of smoke in a building, they are not smoke barriers that can be UL 1784 tested. The air leakage performance of these systems varies on a project by project basis and is, in large part, dependent upon the engineering team designing it. The acceptance testing of pressurization systems conducted by code officials vary greatly.

Life Cycle Maintenance

The life cycle maintenance cost of a fire and smoke barrier system identifies the effort and expense necessary to keep the system functional over the life of the building. It is generally accepted that the more complex and costly a system is to maintain, the less likely it is that owners or facility maintenance personnel will follow the prescriptive requirements.

Swing doors, whether enclosing an elevator lobby or mounted at the elevator door on a magnetic hold open, are highly susceptible to tenant tampering. Many swing doors will swing shut in response to a general alarm regardless of if the alarm is false or real or as a result of a power loss. When deployed incorrectly, these doors interfere with regular building traffic and will often be wedged open by building occupants or tenants. Facility maintenance teams must constantly watch for and remove swing door obstructions to ensure that when there is an emergency the doors are able to function as expected. Beyond vigilantly monitoring for tampering, the closers on swing doors, the apparatus that forces the door to close and latch under its own pressure, must be adjusted periodically to guarantee that the door will work correctly when needed. If the door doesn't latch, it will not function as a fire or smoke barrier.

Rolling magnetic gasketing systems are maintained by facility managers or maintenance staff. Every six months the system should be deployed and rewound to ensure functionality. It does not require oversight from an engineer or licensed third party inspector and the units themselves are hidden in a housing above the elevator door, removing them from view and making it less likely that they will be subject to tampering.

Elevator shaft pressurization systems must be maintained by third party experts with knowledge in mechanical engineering, fire protection engineering, and air balancing. While these complex systems are fairly tenant tamper-proof, the time and expense incurred to maintain the system can be prohibitive.

Flagler Station Marriott Courtyard

Architect Bernardo Sandoval, Associate Project Manager for Beame Architectural Partnership, was able to meet fire and life safety codes requiring enclosed elevator lobbies and maximize the usable space on each floor by incorporating a rolling magnetic gasketing system at the elevator doors. The five-story Marriott Courtyard project constructed in Miami, Florida was required, by the Florida 2004 building code, section 707.14.1, to provide an enclosed elevator lobby on floors two through five. Instead of building the code-prescribed vestibule into his design, Mr. Sandoval specified the rolling magnetic gasketing system at the elevator hoistway and was able to add an additional sleeping room on every floor, increase the size of every unit by six to eight inches, and provide more space in the back of the house. "Using the rolling magnetic gasketing system, instead of an enclosed elevator lobby, I was able to dramatically reduce the size of the corridor and redistribute the saved space in ways that made the building more valuable," explained Mr. Sandoval. "The four extra hotel rooms I was able to add will generate additional revenue for the hotel owner throughout the life of the building and the product that made it possible had a payback period of less than six months."

"Using the rolling magnetic gasketing system, instead of an enclosed elevator lobby, I was able to dramatically reduce the size of the corridor and redistribute the saved space in ways that made the building more valuable," explained Associate Project Manager Bernardo Sandoval. Photo courtesy of Smoke Guard, Inc.

Cost Comparisons

The total cost of these different fire and smoke safety solutions for vertical shafts is a combination of the price of the materials and labor required for installation and the amount of valuable square footage required to add these barriers to the floorplan. The framing and drywall materials required to build an enclosed elevator lobby on each floor may have a minimal price tag, but the significant amount of space required by this solution quickly escalates the cost. Elevator shaft pressurization systems are building-wide systems comprised of fans, ducting, and other equipment that are designed on a caseby- case basis by specialized engineering teams. Just as the design of these systems can differ substantially from one project to the next, so can the cost, which is often significant. Although accordion doors are often hidden from view, the physical weight and materials necessary to incorporate accordion doors onto a project will not go unnoticed. The large, steel curtains weigh a significant amount and considerable construction can be involved to build the deep pocket and create the overhead track. Additionally, if the ceiling is not stable enough, anchors will need to be added to provide the necessary support. A rolling magnetic gasketing system uses fewer and lighter materials than any of the other potential smoke protection devices. This system of high-tech film and magnets adds roughly 60 pounds at each elevator door. The code has always required that the elevator shaft doors be fire-rated to compartmentalize each floor and restrict the movement of fire, so the only additional equipment required to complete the requisite fire and smoke barrier on each floor is the rolling magnetic gasketing system, which mounts above individual elevator doors and requires no valuable floor space.

Areas of Refuge

Since the early 1990s, building codes have required that design teams create spaces in multi-story buildings, usually one per floor, for individuals with mobility impairments to be able to safely wait out the effects of fire. These areas of refuge protect occupants from both fire and smoke. They must be both a fire-rated enclosure and a smoke-rated enclosure to protect occupants unable to move away from the fire event. There are two solutions for architects creating areas of refuge. They can create an area of refuge out of a traditional enclosed elevator lobby that is fire and smoke-rated. Another solution is to use a fire-rated and smoke-rated rolling magnetic gasketing system to enclose and protect the area of refuge.

Fire-Rated/Smoke-Rated Rolling Magnetic Gasketing System

A fire-and-smoke-rated rolling magnetic gasketing system provides a smoke and fire-rated barrier to keep hazardous heat and smoke out of these predetermined safety areas. When smoke is detected at an opening or entrance to the area of refuge, these systems deploy a fire-rated fabric curtain edged with flexible magnets. These magnets attach to auxiliary rails on either side of the opening and create a virtually air-tight seal protecting building occupants from the smoke, toxins, and heat on the other side. Building occupants can easily enter or exit through the deployed screen by either using a screen rewind switch mounted on the screen or by applying less than fifteen pounds of pressure on either side to separate the screen from the auxiliary rails.