1. A fire-resistant material is completely unaffected by flame.
   A fire-resistant material chars and may ignite, but is not destroyed by flame.
2. A fire-resistant material maintains its structural integrity when flame is applied.

A fire-resistant material is one that maintains its structural integrity in a fire for a specified length of time.

1. oxygen and neon
   phosphorus and nitrogen
2. hydrogen and helium

Two of the most effective elements in fire resistance are phosphorus and nitrogen, which are often mixed with polymers (plastics) to form polyphosphazenes.

1. When heated, the material emits a shell of impermeable gas that envelops the structure.
   It creates barriers to heat and flame, slowing the destruction of the building and buying time for help to arrive.
2. It makes it almost impossible for a building to catch fire at all.

When used in buildings, fire resistant material can create compartmentalization, or the containment of a fire to a certain area. In the case of the World Trade Center, which burned down and collapsed during the September 11th attacks, compartmentalization gave many building occupants precious extra minutes to escape to safety.

1. subjection to simulations of fire-like heat and smoke in a lab
   being present in an actual building fire
2. the direct application of flame, pressure and high temperatures to meet predetermined criteria

Requirements for fire resistant classification vary from country to country, so testing can look different depending where you are. In the U.S., at least one side of a material must be exposed to direct heat and flame for a specified length of time. A material's resistance is usually recorded on a time/temperature curve to determine its success or failure.

1. fire penetration, external damage to the material and internal damage to the material
   temperature, smoke penetration and structural integrity of the material
2. fire penetration, temperature and structural integrity of the material

In order to determine fire resistance, materials are assessed based on three qualities: fire penetration (whether the flames can penetrate the material), temperature (how hot the material gets in comparison with established standards) and maintenance of structural integrity (the hose-stream test).

1. silk
   concrete
2. plywood

In the event of a fire, you'd probably prefer to be behind a concrete wall than in your silk-sheeted bed. Concrete will eventually degrade under fire, but it handily passes the fire resistance test and is much hardier than most other materials in a fire.

1. Fire-retardant materials protect structure completely -- but only up to a certain temperature.
   Fire-retardant materials slow a fire's progression, but there is no requirement that they maintain any structural integrity when introduced to flame.
2. Fire-retardant materials guarantee that there is no damage to the structure at all.

Fire-retardant materials must slow the movement of a fire; however, there is no requirement that structural integrity is maintained. Fire resistance, which does require the structural element, is a more stringent classification.

1. The glazes and sealants often used to coat concrete surfaces can be flammable even though the concrete itself is fire resistant.
   If the concrete is mixed incorrectly, it loses its fire resistant properties.
2. Cracks in concrete significantly reduce its ability to resist flame, as heat can more easily penetrate the material.

When used for things like countertops, concrete is often finished with a non-fire resistant wax or sealant. This won't degrade the abilities of the concrete itself to resist flame, but it can cause the surface to ignite where an unfinished slab would not.

1. mold and other potential natural toxins
   environmental degradation such as carbon dioxide emissions
2. hurricanes, tornadoes and floods

Although it's not as pretty, concrete is significantly stronger and more resilient than wood. As a result, it offers greater protection against a wide variety of natural disasters, including hurricanes, tornadoes and floods.

1. Asbestos fibers can cause buildup of scar tissue in the lungs that, in time, can severely impede breathing ability.
   When introduced to heat, asbestos gives off toxic fumes that often cause more damage than the fire it protects against.
2. Termites breed in asbestos, which can pose a major risk when used in wood-framed homes.

In many older buildings, asbestos was used for insulation and fire resistance; however, it can cause some serious harm to lungs. It's no longer used in construction, but its ill effects can surface years after exposure.