Our Solution: A Buckled Wall
CBI was recently called out to investigate a buckling brick wall in the South End of Boston. The building is a 19th century former whiskey distillery turned into artist studios. The property owner was rightly spooked by the sight of an exterior wall bowing out, threatening to separate from the floor framing it supports, and possibly drop bricks on cars parked below.
CBI and the owner’s contractor performed a simple masonry drilling test to determine the thicknesses of the walls at different levels of the building. The contractor drilled holes through all brick wythes, and the thickness was measured. The bowing wall was between floors 2 and 3 of a 3-story section of the building. The upper wall (roof to floor 3) was found to be 12” thick, the bowed section between floors 3 and 2 was 8” thick, and the lower wall between floors 2 and 1 was 16” thick.
We first sought to understand what caused the failure. The 12” wall was not centered above the 8” wall; instead, their exterior faces were flush. It is possible that the eccentric loading of the heavier wall above (wall weight, roof loading, and 3rd floor loading) caused the 8” wall to buckle, and that the buckling increased with prolonged loading and secondary effects. It is also possible that as the wall buckled, the negligible tension capacity of the century-old mortar was exceeded, leading to exacerbated buckling of the wall in addition to secondary effects from floor loading above.
The decision was made to replace the full height of the wall from the foundation to the roof with a new CMU wall. The challenge now is designing temporary shoring to allow the contractor to demolish the wall without risking a sudden failure of the roof-to-2nd floor section.