Typically, a fire rating measures the duration for which a passive fire protection system can withstand a standard fire resistance test. Depending on country, the rating system and specifications vary. Nevertheless, the rating can be quantified simply as a measure of time, or it may entail a host of other criteria, involving other evidence of functionality or fitness for purpose.
The difference between a fire retardant and a fire resistant rating
Fire-retardant materials should not be confused with fire-resistant materials. A fire retardant is essentially any substance that burn slowly and does not contribute to a fire. Thus any material that because of its composition slows or stops the spread of fire or reduce its intensity is fire retardant. Commonly used materials used when building; such at cement, mineral wool, bricks, concrete and glass are by nature fire retardant. When testing a product the authorities look to measure the product’s ability to slow down horizontal flame spread and smoke development. A stringent room test also measures the ability of the product to prevent vertical fire spread and delay flashover.
A fire resistant material is one that is designed to resist burning and withstand heat.
A fire resistant has the ability to resist fire penetration through commonly used wall and ceiling assemblies. This ability is measured by time ratings, often required by building codes. The test criteria is the standard time/temperature curve and the ratings on assemblies are granted based on the duration of the test (1 hour, 2 hours…).