May 7, 2024 by Yannick Roy and Wei Chiet Thong, J.S. Held
Reports of wood-framed roof collapses, ranging from simple agricultural roofs to complex roofs in industrial buildings, are frequent in North America.
These collapses often are caused, or contributed to, by controllable factors like lack of maintenance, chemical attacks, moisture attacks, or inadequate materials, design or construction. Ignoring Negligent handling of controllable factors can sharply increase the scale and scope of insurance-related damages.
Pitched wood-framed roofs are commonly used for residential and agricultural structures, whereas commercial structures frequently use flat wood-framed roofs. Both types often use prefabricated wood roof trusses, which strongly resist vertical loads but are less well suited to resisting lateral loads.
Increasingly, wood-framed roof collapses happen during significant weather-related events, such as windstorms and heavy snowfalls. If loads approach the capacity of the trusses or bracing system, the roof structure will begin to deform. It doesn’t take much more load to trigger failure or collapse.
Well-designed and braced structures are significantly more resistant to collapse – for example, collapse zones are localized in the case of snow overloading, as opposed to a complete roof and/or structure collapse in poorly braced structures.
In many cases of truss failure, investigations find preventable contributing factors, including:
Yannick Roy is a regional lead in J.S. Held’s Forensic Architecture and Engineering practice, and Wei Chiet Thong is a senior engineer in J.S. Held’s Forensic Architecture and Engineering practice.
Feature image courtesy of iStock.com/Bryngelzon