This Construction Brief will give you an overview of ISO's Construction Class 3 — noncombustible construction. When you‘ve completed this course, you'll know what an ISO report means when it says a building is noncombustible construction. And you'll understand why a particular structure is—or isn't—noncombustible.


  • Buildings with exterior walls, floors, and roofs of noncombustible or slow-burning materials
  • Building supports of noncombustible or slow-burning materials
  • Noncombustible or slow-burning roof decks on noncombustible or slow-burning supports—regardless of the type of insulation on the roof surface

Advantages of noncombustible construction

  • Easy to erect
  • Economical to build
  • Uses materials that don‘t readily burn

Disadvantages of noncombustible construction

  • Contains steel, which looses strength at high temperatures
  • Highly damageable buildings
  • Unstable buildings under fire conditions
  • Uses slow-burning materials that do burn—adding fuel to a fire