Which type of construction allows shafts and spaces between walls?

Ordinary construction is characterized by exterior walls made of non-combustible materials such as brick or concrete, but may include interior elements that are combustible, like wood. It often features voids or spaces between walls, such as those created by the installation of utility shafts or HVAC systems. These shafts can present challenges during a fire, as they can act as channels for smoke and flames, allowing fire to spread quickly between floors.

In contrast, heavy timber construction utilizes large, solid wood members that provide structural integrity and greater fire resistance, thereby limiting the presence of void spaces that could facilitate fire movement. Type I construction involves non-combustible and fire-resistive materials, minimizing the potential for vertical fire spread through shafts. Type II construction is similar to Type I but may include some combustible materials, still focusing on limiting fire spread.

Thus, ordinary construction stands out as the type that specifically accommodates spaces and shafts between walls, making it critical for understanding fire behavior and safety considerations in firefighting scenarios.