Greenslopes Private Hospital Cooling Tower Plinths

The roof of the Central Energy Building has three layers: a structural slab, a waterproof membrane, and a topping slab over both. Seating 36 new concrete columns and their hobs meant cutting into the top layer and drilling starter bars into the structural slab, leaving the membrane untouched and the structural slab uncut. A mistake puts water into a hospital plant room or weakens the slab holding the plant up. We did this builder's work for Johnson Controls.

GPR scanning set the method. It measured the topping slab thickness at every hob before a saw depth was set, and located the reinforcement in the structural slab so every starter bar could be placed to miss it. The hobs were waterproofed and lapped into the existing membrane, and the topping slab, removed only in the hob footprints, was reinstated to match. The roof went back together as one continuous system.