Forensics of a Partially Collapsed Timber Roof

The roofing of an office building partially collapsed after being in use for almost twelve years. The author was appointed as an independent structural expert to investigate the damage event, by approval of all involved parties, i.e. owner, building insurer and roof constructor. The expert report should give answers to several questions related to forensic engineering, e.g. reasons for the partial failure of the roof elements; influence of the snow load present at the moment of partial collapse; faults or deficits in the structural concept, in element production or execution etc. The paper reports on the course of events and actions, the structural and architectural conception of the roofing, its structural behavior, determination of updated failure loads, associated structural safety assessment and degrees of compliance. The paper gives no conclusion on legal or insurance issues.