A rating of the length of time it takes a fire to penetrate a barrier. Designates the ability of a material to contain a fire in a carefully controlled test setting for a specified period of time. A material tested in a laboratory that adequately contains a fire for two hours and meets other requirements during the laboratory fire test, it is given a two-hour fire resistance rating. Fire-resistance ratings are based on full-scale tests under controlled conditions and are generally recognized by building code authorities and fire insurance rating bureaus. Requirements for fire-resistance ratings are usually set by local building code officials based on the expected occupancy of the building.

The classifications indicating in time (hours) the ability of a structure or component to withstand fire conditions.

The rating given a commercial structure classifying it as a one, two or three-hour rating, as defined by the National Fire Code or Uniform Fire Code. Different components of a building may be rated separate from the entire building, such as the ceiling, walls, or exterior.