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This article originally appeared in the March 2009 edition of Construction Executive.

Divided Spaces: Building Compartmentation Plays a Critical Role in Fire Safety

By Jeff Razwick

Protecting people and property during building fires requires three essential design features: alarms to provide early warnings of danger, 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 for firefighters to arrive.

In some situations, however, building codes allow the reduction or elimination of fire-stopping compartment ratings in exchange for the installation of sprinklers. Such code trade-offs may provide incentives that offset the cost of sprinkler installation. Yet, despite their significant benefits and proven track record, sprinklers are not infallible.

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.

This article discusses the role of compartmentation in balanced fire protection, along with options for fire-rated materials in designs that incorporate glazing for daylighting, aesthetic or security needs.

The Problem with Sprinkler Trade-Offs

Automatic sprinkler systems have played a major role in improving building safety. According 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 sprinklers’ strong role in life safety and property protection, the International Building Code (IBC) increasingly encourages their installation. In exchange, it may allow reductions in certain compartmentation requirements, such as lowering or eliminating ratings for fire doors and fire-resistant wall assemblies in corridors.

Nevertheless, there is substantial disagreement on whether such trade-offs are appropriate in light of potential sprinkler failures and recalls.

James Burns, New York State Fire Administrator and president of the National Association of State Fire Marshals (NASFM) expressed concerns in a February 2006 USA Today article: “We think we’ve gone too far with the tradeoffs in the codes, and we’re seeking to reverse that trend. With all the tradeoffs we’ve got now, we’re afraid a building with one of these faulty sprinklers is going to burn.” Maine State Fire Marshall John Dean added: “There’s no question that a sprinkler system provides great, great protection, [but] we don’t want to put all our eggs in one basket.”

The issue is that sprinklers require a number of steps to activate. Before this can happen, the system must be adequately designed, properly maintained and have sufficient water or power supply during an emergency. NFPA data show that sprinklers fail in about one out of every 10 fires.

There are several areas in which the systems can fail, including damage to sprinkler heads, pipe corrosion, and mechanical failure in water supply pumps. Because they may sit for many years without use, absent regular inspection and maintenance, system reliability could be compromised.

A properly designed and maintained system may also 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 ten installed in the United States since 1991.

In situations where code trade-offs 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 of slowing or stopping the spread of fire was with the building materials themselves. Heavy materials like stone and brick provided inherent resistance to fire.

As building designs have evolved, walls, floors and ceilings have become 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.

With the desire for more open and comforting indoor environments in offices, schools, and other public and commercial buildings, glazing is often a key design element. 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.

In areas where fire protection is required, fire-rated glass is specified to help provide building compartmentation. A fire rating is required since ordinary window glass cannot hold up to the high temperatures generated from building fires.

Many fire-rated glass options are now available, and offer a number of additional performance characteristics that can 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 a range of make-ups that can provide many different performance characteristics. These include fire ratings up to three hours, high impact safety ratings and sound reduction, among others. In this category, an example product is the FireLite® family of ceramic glass.

While fire-rated ceramic glass works well in many applications, other products should be used in instances where it is necessary to protect people and equipment from high heat. Ceramics can withstand the high temperatures of a fire without breaking, but they allow heat to pass through.

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 2 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 thus be used throughout a building’s design to provide visibility, security and light, as well as effective compartmentation. One type of glass firewall is Pilkington Pyrostop™.

Balanced Fire Protection

While compartmentation that uses fire-rated glass and other materials is a critical part of fire-safe building designs, it, too, is not a panacea.

In an evaluation of a 1993 New York City high-rise fire that 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 that for high-rise buildings, compartmentation was not an equivalent substitute.

Passive building protection in the form of compartmentation, and active systems in the form of sprinklers and alarms, work together to provide balanced fire protection. Today, more building industry professionals advocate this multi-pronged approach as the rational way to protect people and property.

Kurt Roeper, manager of global codes and standards for Ingersoll Rand Security Technologies, in a February 2007 article in Doors and Hardware magazine succinctly states this point: “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.”

The trade-off debate typically revolves around whether building owners can afford to include both active and passive systems. While there are higher up front costs to a balanced approach, relying on a single system can result in catastrophic loss of life and property. As history demonstrates, 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.

Jeff Razwick is the Vice President of Business Development for Technical Glass Products (TGP), a Snoqualmie, Washington-based supplier of fire-rated glass and framing systems, along with specialty architectural glass products. www.fireglass.com, 800-426-0279

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