Which construction type involves heavy timber with noncombustible exterior walls?

The construction type that involves heavy timber with noncombustible exterior walls is indeed Type 4 construction. This method is recognized for its substantial use of wood, particularly heavy timber elements, which are designed to resist fire better than lighter wood construction. The heavy timber provides structural integrity and can withstand fire without collapsing as quickly as lighter wood frame structures might.

In Type 4 construction, the noncombustible exterior walls serve to protect the timber framework from direct fire exposure. This combination not only enhances fire resistance but also contributes to the overall durability of the structure. Typically, you can expect these buildings to be more robust and have a longer fire resistance rating compared to those constructed using lighter materials or different types of construction that do not incorporate heavy timber.

This construction type is often used in buildings where a combination of aesthetics and durability is desired, such as in commercial spaces or large assembly areas. It represents a unique balance of materials that capitalize on the benefits of both wood and noncombustible materials.