Firestopping works to slow the spread of fire and smoke through a building with the use of fire and smoke barriers to compartmentalize and contain the fire to a specific area. Those barriers can be fire rated walls, ceilings, and floors (for example) and they must be maintained to ensure the integrity of a building during a fire.
"F" Rating -The "F" Rating defines the amount of time before flame pokes through openings to the unexposed side of the test assembly. Most Contractors are familiar with the Fire Rating of a wall, floor or door being stated as "1 hour" or "2 hour".
"T" Rating -The "T" Rating defines the amount of time for the surface of the penetrating item on the non-fire side of the test assembly to rise 250F plus ambient temperature.
"L" Rating -The "L"Rating measures the amount of air that moves through an opening in cubic feet per minute per square foot of opening area, at ambient temperatures and 400F. The two temperature levels simulate cold and hot smoke moving in a building. Many firestop systems have L Ratings of less than one.
"W" Rating - The "W" Rating measures resistance of a firestop product to standing water in buildings. Developed to address concerns by building owners about the ability of a firestop system to resist the passage of water through floor assemblies, the W rating development offers a new quantifiable characteristic for a firestop system. The test protocol simulates water on a firestop system for 72 hours, under a 3' head of water.