FIRE PERFORMANCE FAQS
HOW ARE BUILDING ASSEMBLIES RATED FOR FIRE RESISTANCE?
ASTM E 119 establishes the effectiveness of a building assembly to act as fire barrier over time. These are large components including walls, floor-ceiling assemblies, roofs and windows and doors. A wall assembly is tested for structural integrity and the ability to contain a fire. The assembly is mounted to a specially-constructed furnace. Gas burners are lit as thermocouples record temperatures. Gas flames, mimic heat from an adjacent fire. Observations are made through viewing windows in the furnace and with instrumentation. Temperatures and time to system failure are recorded. A hose stream test follows to measure the assembly’s resistance to water pressure.
ASTM E 119 uses a furnace heating schedule—a timed increase of temperature—which brings the furnace up to 1,000 degrees Fahrenheit in five minutes, up to 1,700 degrees Fahrenheit in one hour, and to 1850 degrees Fahrenheit in two hours. Assemblies must survive these temperatures to be successfully fire rated at each time interval.
WHY ARE BUILDING CODES CONCERNED WITH FIRE SAFETY?
Life safety is the principle reason for fire codes. Over the years, fire safety concerns have evolved and today all building codes require that building materials and systems be evaluated for fire performance. There are two national code organizations the International Fire Code, or IFC and the National Fire Protection Association, NFPA.
In general, codes attempt to establish minimum safety requirements. Building codes are specific to at least three criteria:
- Type if occupancy
- Intended use
- Type of construction
All building materials are evaluated and rated for flammability, especially interior finishing materials. Constructions and components are rated for combustibility and assemblies are rated for fire resistance.
WHAT CHARACTERISTICS OF THE FIRE ARE MEASURED DURING A MATERIAL TEST?
The science of fire considers a number of characteristics when materials are tested for fire-safety. Objective testing measures:
- Ignition times
- Rate of temperature increase
- Flame propagation
- Rate of burning
- Smoke generation and properties
- Subjective observations
HOW ARE EXPOSED BUILDING MATERIALS RATED FOR FIRE?
Building materials, products or complete assemblies that are exposed to the living space of a building must be tested using ASTM E 603. A corner of a room is constructed in an accredited testing facility, using standard building materials. Materials to be tested are mounted on the walls and ceiling of the room corner. A fire source—either a wood crib or a diffusion burner—is placed in the corner and ignited. The test mimics a waste basket sized fire that spreads to something nearby. To perform satisfactorily the tested material must not spread the fire or generate excessive amounts of smoke. The test observes the fire over time from ignition to flashover into the next room or space. The room corner test measures temperatures over time, smoke generation, time to flashover, combustion gas, and total energy release rates.
HOW DO GYPSUM WALL BOARD ASSEMBLIES CONTRIBUTE TO FIRE RESISTANCE?
Fire resistance is an important factor that influences the specifications for most building designs today. Since gypsum is a naturally fire-resistant mineral, it has become a leading construction material and component of fire-resistance rated wall assemblies. To ensure that these gypsum board wall assemblies are appropriate to specify in fire-rated building designs, the complete wall assembly undergoes fire tests and fire resistance classifications are established accordingly. There are several types of fire-resistant wall assemblies to suit a variety of applications and projects. Noncombustible and combustible / loadbearing and non-loadbearing are examples of fire-resistant wall assemblies. Area Separation Firewalls are required between adjacent townhouses, apartments and commercial buildings.
HOW ARE SURFACE BURNING CHARACTERISTICS OF BUILDING MATERIALS MEASURED?
ASTM E 84 is the test method used to determine the rate of flame spread and smoke development of building materials, in other words, surface burning characteristics. A long “Steiner Tunnel” apparatus is used in this fire test. The test chamber is approximately 25 ft. long and 2 ft. by 2 ft. in cross-section. Materials to be tested are placed on top of the tunnel and ignited. At the same time a clock is started. The flame spread index is determined as an operator tracks the leading edge of the flame using a pointer that is mechanically tied to a computer. Smoke spread index is measured by an optical sensor which measures and records the smoke density.