What type of insulating material is commonly found in fire-rated walls?

Mineral wool, often referred to as rock wool or slag wool, is commonly used as an insulating material in fire-rated walls due to its excellent fire-resistant properties. This type of insulation can withstand high temperatures without melting or releasing harmful smoke and gases. It is non-combustible and has a high melting point, typically above 1,800 degrees Fahrenheit, which makes it ideal for use in applications where fire resistance is crucial.

In addition to its fire-resistant qualities, mineral wool provides good thermal insulation and sound dampening, making it a versatile choice for both fire safety and comfort in buildings. Its ability to maintain structural integrity under heat contributes to the overall effectiveness of fire-rated walls, which are designed to contain and limit the spread of fire in a building.

While other materials, such as fiberglass and polystyrene, have their applications in insulation, they do not provide the same level of fire resistance required for fire-rated construction. Cellulose, although it has some fire-retardant treatments, typically does not perform as well in extreme heat compared to mineral wool. Hence, mineral wool stands out as the preferred choice for fire-rated walls, ensuring safety and compliance with building codes.