Flat-Roof Fires in Three- to Six-Story Apartment Buildings

Coquitlam forms part of the Greater Vancouver region and has a population of approximately 140,000. It has experienced rapid population growth and building development since the 1960s. Much of the new residential construction has been Type 5, wood-frame apartment buildings, designed to increase population densities in targeted urban areas. I have responded to several flat-roof fires that have impacted these types of structures. These fires exposed the challenges associated with fire that extends from the exterior of the building into the flat-roof area. I have developed techniques and instructional materials to aid incident commanders (ICs) in accessing and implementing tactics that can help reduce fire losses while improving firefighter safety.

ICs often hesitate to send firefighters to roof areas for offensive operations. If not properly assessed, roofs can be unpredictable and dangerous depending on construction and fire exposure. Flat roofs built with dimensional lumber as part of the Type 5 construction (commonly referred to as wood or stick frame), often seen in condominiums and garden apartments, offer firefighters an opportunity to work safely from roof positions adjacent to the fire area. Too often, a lack of building construction knowledge leads ICs toward defensive tactics that are unnecessary given the inherent safety and support these roof systems provide. This article dispels myths about working on solid wood-beam roofs; these arguments are backed by personal experience; interviews with numerous building experts; as well as information from the preeminent expert on building collapse, Fire Department of New York Deputy Chief (Ret.) Vincent Dunn.

Dunn wrote extensively on the prospect and dangers of building collapse. In his book Collapse of Burning Buildings: A Guide to Fire Ground Safety (1988), he noted that the solid wood beam roof (made up of dimensional lumber spaced on 16-inch centers) provides the greatest stability to a flat roof.”1 Dunn added that this type of roof also will show signs of “softening” on the roof deck that can warn firefighters that the roof may be weakening. For the experienced fire officer, this is essential knowledge that can impact tactical choices on the fireground. Understanding that this roof system provides the opportunity for a safe working environment is critical.2 Quick interior attack and search operations coupled with a roof reconnaissance team give an IC the opportunity to quickly assess fire spread into the roof void. From the ground, an IC can be provided a three-dimensional view of the building (exterior, interior, and top) by way of information from officers working on the interior, exterior, and roof. This, in turn, should lead to better strategies and tactics that ultimately will limit fire losses.