Which material is used in the structural frame for Type I construction?

Which material is used in the structural frame for Type I construction?

• A. Heavy timber
• B. Insulated 2 × 4
• C. Protected steel
• D. Aluminum studs

Answer: (C)

Type I construction is fire-resistive and relies on a noncombustible structural frame. When steel is used for this frame, it must be protected with fireproofing to maintain its strength during a blaze. That combination—steel carrying the load but with protective coating or enclosure to withstand heat—is why protected steel is the correct choice. Heavy timber corresponds to Type IV, which uses large wooden members. Insulated 2x4 and aluminum studs are not used for the structural frame in Type I buildings; they’re either used for non-loadbearing walls or have insufficient fire resistance and strength for a fire-resistive frame.

Type I construction is fire-resistive and relies on a noncombustible structural frame. When steel is used for this frame, it must be protected with fireproofing to maintain its strength during a blaze. That combination—steel carrying the load but with protective coating or enclosure to withstand heat—is why protected steel is the correct choice. Heavy timber corresponds to Type IV, which uses large wooden members. Insulated 2x4 and aluminum studs are not used for the structural frame in Type I buildings; they’re either used for non-loadbearing walls or have insufficient fire resistance and strength for a fire-resistive frame.