Swinging stage installed to enable access to repair perimeter roof slab


Shear spalling to roof slab due to wearing slab topping movement


Structural propping installed to support parapets.


We were engaged to advise on concrete spalling and waterproof failure to the perimeter of a highrise residential roof. After investigation, it was determined that the wearing roof slab (which enables falls on the roof) was suffering thermal movement and inducing shear stress on the parapet causing significant structural spalling. The mechanism was determined as thermal differences in compression (lower night temperatures) allowed non-compressible debris to enter the exposed slab control joints and thermal expansion (day) exerted shear force on the parapet. The wearing slabs were effectively becoming a “walking”and resulting in structural and waterproofing failure. We designed and superintended an economical solution for rectification.