A fire rating is a way of classifying building materials based on how well they resist fire. It essentially tells you how long a material can withstand a fire before failing. Fire ratings are important for ensuring the safety of buildings and their occupants in case of a fire.

There are different fire rating systems used around the world, but they all generally assess three main aspects of a material's fire performance:

• Flame spread: This measures how quickly a fire will spread across the surface of the material.
• Heat transmission: This measures how well the material can block heat from radiating through it.
• Smoke production: This measures how much smoke the material will produce when it burns.

Fire ratings are typically expressed as a number or a letter code. For example, in the US, a common fire rating system uses numbers like "30" or "90," which indicate the number of minutes a material can withstand a standard fire test.

Here are some resources that you might find helpful to learn more about fire ratings: