Forensic Investigation of Metal-Plate Connected Wood Truss Roof Damages and Collapses: Cases, Causes, and Solutions

Investigations of construction related metal-plate-connected wood truss collapses may involve multiple engineers or other experts. Often, one or even all of the investigators will determine the temporary truss bracing and anchoring did not satisfy relevant guidelines. One or more investigators may then prematurely and incorrectly conclude the collapse was caused by inadequate anchoring or bracing. Many long-standing buildings have trussed roofs with only minimal bracing, far below current industry norms. Inadequately braced truss systems that have stood for years or decades are sometimes discovered in a pre-collapse condition. Often, it is feasible to repair resultant damages and install appropriate bracing to restore the roof truss system to a functional and safe condition. Thus, lack of recommended bracing does not always result in collapse but may be the cause of the collapse being investigated. “Adequacy” and “conformance with a guideline” are not interdependent concepts. Examples of well braced truss system collapses are reviewed to illustrate how other, equally important factors can contribute to truss collapses. It is necessary to evaluate all of the possible causes of a collapse to reach a definitive conclusion about the actual cause(s). Concluding that the truss bracing did not conform to a particular guideline or design is not the same as concluding that inadequate bracing was the cause of the collapse. It is not that simple.