Which type of construction does NOT allow combustible fire walls?

• A. Type II
• B. Type III
• C. Type IV
• D. Type I

Answer: (D)

Type I construction is characterized by non-combustible materials used for both structural and non-structural elements. In this type, fire-resistance-rated assemblies are critical, as they are designed to withstand fire exposure and prevent the spread of fire between different areas of a building. This requirement for fire-resistive construction means that combustible materials, such as wood or plastic, are not permitted in fire walls, which serve as critical barriers to fire spread.

In contrast, the other types of construction—Type II, Type III, and Type IV—allow for varying degrees of combustible elements. Type II construction may include some non-combustible materials but permits more flexibility with combustible materials than Type I. Type III construction allows for the use of combustible materials in the building’s exterior walls, while Type IV (also known as heavy timber construction) relies on large wooden members, which are combustible. Therefore, Type I construction, with its strict adherence to non-combustibility standards, is the only type that does not allow for combustible fire walls.