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How do gypsum wall board assemblies contribute to fire resistance?

Fire resistance is an important factor that influences the specifications for most building designs today. Since gypsum is a naturally fire-resistant mineral, it has become a leading construction material and component of fire-resistance rated wall assemblies. To ensure that these gypsum board wall assemblies are appropriate to specify in fire-rated building designs, the complete wall assembly undergoes fire tests and fire resistance classifications are established accordingly. There are several types of fire-resistant wall assemblies to suit a variety of applications and projects. Noncombustible and combustible/loadbearing and non-loadbearing are examples of fire-resistant wall assemblies. Area Separation Firewalls are required between adjacent townhouses, apartments and commercial buildings.

 Whole systems, not just the individual building materials, need to be tested to verify the fire performance. Various factors influence fire resistance:

  • The type of gypsum board is critical. Board with glass fibers in the core provides better fire resistance than gypsum board without glass fibers.
  • The fire resistance of wall assemblies with regular (standard) gypsum board increases as the density of the gypsum board increases.
  • Layering the number of gypsum board on each side of the assembly from one to two improves the fire resistance rating. 

Other system factors that impact the fire performance of wall assemblies include the type and installation of insulation, the type of stud and the arrangement of the studs within the wall.

Well constructed and tested gypsum board wall assemblies offer a first line of defense against the spread of fire and lead to a more sustainable building.


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