Why Did These Historic Masonry Buildings Fail?

The role of engineering judgement and contractor experience is illustrated through two case studies where renovation work led to failure of designated historic masonry buildings located in Ontario, Canada. In the first case study, neglecting the pre-existing deterioration and bulging of the masonry exterior wall, and lack of assistance from a structural engineer during sidewalk replacement adjacent to the building’s wall caused a portion of the exterior wall to collapse. The second case involved a project to lower the basement floor in a semi-detached house. Design drawings for the project lacked adequate information on temporary support during construction. The engineer allowed the contractor to remove the entire slab ahead of underpinning. With the floor slab removed and without adequate lateral bracing, part of the foundation wall failed upon the removal of the soil for underpinning.