Protecting people and property during building fires requires three essential design elements: alarms to provide early warnings, automatic sprinklers or other suppression systems, and fireproof compartments to contain flames and smoke. These elements work together to give occupants time to escape and firefighters time to arrive.
Eliminating any one of the three fire protection elements—detection, suppression or compartmentation—is akin to designing a high-rise tower with only vertical and horizontal framing members and no cross bracing. It compromises the integrity of the building.
Contractors must consider the role of compartmentation in balanced fire protection, along with options for fire-rated materials that incorporate glazing for daylighting, aesthetic and security needs.
The Problem with Sprinkler TradeoffsAccording to the National Fire Protection Association (NFPA), “When sprinklers are present, the chances of dying in a fire are reduced by one-half to three-fourths, and the average property loss per fire is cut by one-half to two-thirds.”
Because of automatic sprinkler systems’ strong role in life safety and property protection, the International Building Code (IBC) encourages their installation. In exchange, the IBC may allow reductions in certain compartmentation requirements, such as lowering or eliminating ratings for fire doors and fire-resistant wall assemblies in corridors.
However, substantial disagreement exists on whether such tradeoffs are appropriate in light of potential sprinkler failures and recalls.
Sprinklers require a number of steps to activate; plus they must be adequately designed, properly maintained and have sufficient water or power supply during an emergency.
NFPA data show sprinklers fail in about one out of every 10 fires. The systems can fail for several reasons, including damage to sprinkler heads, pipe corrosion and mechanical failure in water supply pumps. Because they may sit for many years without use, system reliability could be compromised without regular inspection and maintenance.
A properly designed and maintained system also may fail to provide protection if it is inadvertently turned off before a fire starts. According to the NFPA, this is the single largest cause of failure, occurring in about two-thirds of failure incidents.
Exacerbating the problem is the large number of sprinkler recalls in recent years. Manufacturers recalled approximately 45 million defective sprinkler heads from the late 1990s through 2006—nearly one in every 10 installed in the United States since 1991.
In situations where code tradeoffs allow reduced compartmentation, sprinkler failure can leave a building and its occupants woefully under-protected.
Specialized Fire-Stopping Materials
Before the advent of automatic sprinkler systems, the primary way to slow or stop the spread of fire was through building materials. Heavy materials like stone and brick provided inherent resistance to fire.
As building designs evolved, walls, floors and ceilings became thinner, requiring specialized materials and practices to provide passive fire protection. Fire-rated glazing is one class of materials that works in conjunction with sealants, fire dampers and other products to support compartmentation
Glazing is a key way to achieve more open and comforting indoor environments in offices, schools, and other public and commercial buildings. Also, as architects and designers explore ways to capture natural light to meet green building goals and to provide visibility for enhanced security, glass is a top choice.
When glass is specified to help provide building compartmentation, a fire rating is required because ordinary window glass cannot hold up to the high temperatures generated from building fires.
Many fire-rated glass options are now available with performance characteristics that support a wide range of design needs.
For example, transparent sheets of ceramic can be produced to look like ordinary window glass. Fire-rated ceramic glass offers great design flexibility, with fire ratings up to three hours, high-impact safety ratings and sound reduction.
Ceramics can withstand the high temperatures of a fire without breaking, while allowing heat to pass. While fire-rated ceramic glass succeeds in many applications, other products should be used when it is necessary to protect people and equipment from high heat.
For corridors, stairwells or other critical fire separation areas, glass firewalls may be appropriate. Glazing in this category is tested to the same standards as solid walls, with fire ratings up to two hours. In addition to stopping flames and smoke, glass firewalls block the transfer of radiant and conductive heat, similar to a fire-rated masonry wall. They can be installed from wall to wall and floor to ceiling, and include glass doors.
Glazing can be used throughout a building’s design to provide visibility, security and light, as well as effective compartmentation.
Balanced Fire Protection
After a 1993 New York City high-rise fire caused $10 million in property damage, the U.S. Fire Administration evaluated the role of compartmentation versus sprinklers.
A key issue in the evaluation was the effectiveness of a local law that allowed compartmentation as an alternative to sprinklers. The report concluded compartmentation was not an equivalent substitute for high-rise buildings.
Passive building protection in the form of compartmentation, and active systems in the form of sprinklers and alarms, must work together to provide balanced fire protection. Today, more building industry professionals advocate this multi-pronged approach as the most effective way to protect people and property.
“History has shown that neither passive or active technology can provide absolute protection by itself, but a combination of the two will most always be more effective than either alone,” states Kurt Roeper, manager of global codes and standards for Ingersoll Rand Security Technologies, in the February 2007 issue of Doors and Hardware magazine.
The tradeoff debate typically revolves around whether building owners can afford to include both active and passive systems. While a balanced approach costs more upfront, relying on a single system can result in catastrophic loss of life and property. Large fires can cost millions of dollars in direct damage, along with lost business opportunities and potential liabilities.
With modern materials, incorporating compartmentation does not need to limit design options. Fire-rated glazing, specialty doors and other products offer protection and aesthetics, and can be an important part of a comprehensive fire protection plan.