Understanding Type III Construction

According to the International Building Code (IBC) 2021, Section 602.3, Type III construction is a mix of noncombustible and combustible materials.

Exterior walls must be noncombustible or fire-retardant-treated wood, while interior structural elements (such as floors, roofs, and partitions) can be wood.

2. Common Uses of Type III Construction

Churches, schools, apartment buildings, and mercantile (retail) structures are often built using Type III construction because it balances fire resistance with cost-effectiveness.

Many low-rise residential and commercial buildings use this type due to its ability to support multiple stories while maintaining some fire protection.

3. Verification of Other Options

Option A (Type I) – Incorrect, as Type I construction is entirely noncombustible (steel/concrete) and used for high-rises, not typical for churches, schools, or apartments.

Option B (Type II) – Incorrect, as Type II construction is fully noncombustible but has lower fire resistance than Type I, mainly used for commercial buildings, warehouses, and low-rise offices.

Option D (Type IV) – Incorrect, as Type IV (heavy timber) is rarely used for schools and apartments, though some older churches may use it.

Reference Sources:

International Building Code (IBC) 2021 – Section 602.3 (Type III Construction Definition)

NFPA 220: Standard on Types of Building Construction

ICC Fire Inspector II Study Guide (2021)

Thus, the correct and verified answer is: C. Type III. ✅