Are combustible concealed spaces allowed in Type IV construction?

In Type IV construction, also known as "heavy timber" construction, combustible concealed spaces are not permitted. This construction type is characterized by the use of large timber members, which can better resist fire for a certain period due to their mass. However, the overall intent of Type IV construction is to limit the spread of fire and smoke, and therefore the inclusion of combustible concealed spaces would compromise this safety objective.

The absence of concealed spaces reduces the risk of hidden fires spreading undetected throughout the structure, which is a significant concern in fire safety design. Instead, Type IV construction typically employs non-combustible materials in concealed areas, ensuring that any potential fires that may start in these spaces can be more readily detected and controlled.

Understanding this principle is crucial for fire safety professionals as it guides compliance with building codes and enhances the safety of occupants and firefighters alike during emergencies.