The busy main entrance of downtown high-rise office tower, M&I Plaza, had undergone years of deferred maintenance since its original construction in 1988. New ownership and onsite property management teamed up with Western Specialty Contractors to tackle severe plaza deterioration and water leak issues from the plaza into the underground parking garage. Western’s expertise in solving plaza related problems and troubleshooting difficult repair situations led to CBRE awarding the Indianapolis Branch a contract to perform the necessary repairs.
During the investigation, it was discovered the failed waterproof membrane between the garage roof and topping slab was causing leakage into the garage below, but that wasn’t the only issue. The original design of the topping slab covering the structural concrete deck consisted of very thin granite pavers set in mortar intended to provide surface drainage to two area drains located near the center of the plaza. A majority of pavers were cracking due to the deterioration of the setting bed underneath the pavers caused by water entering failed caulk and mortar joints around the pavers. The potential for trip hazards was a major concern for building management and their tenants. Furthermore, water drainage issues and defects from original construction existed throughout the plaza causing severe corrosion of structural elements at the base of large granite clad concrete columns.
The Solution/ Scope of Work:
Western worked closely with building management and the manufacturer to develop an innovative solution and detailed scope of work. Western installed 2’ by 2’ pavers on high-tab pedestals with open joints between the pavers to allow water to drain freely below the walking surface to drains located at the structural roof level. Surveying had been done during preliminary exploratory work to ensure the underlying garage roof had the correct slope to direct the water to existing drains. The existing topping slab, consisting of both concrete and granite pavers, and failed waterproof membrane needed to be completely removed down to the structural concrete deck. Repairs made to the structural concrete and prep work to the existing substrate was necessary for the success of the newly hot-applied waterproofing membrane system being installed. The system also included a drainage mat to filter and direct water to the drains, and additional drains were installed to provide drainage in some locations. Once the new membrane was installed, a water test of the entire plaza was performed and passed. Approximately 2,000 new granite pavers were then installed.
Prior to the start of the project, a mutually agreed upon schedule and phasing plan was developed with building management to keep the busy main entrance open throughout the five-month long project.
The project was completed on time and within budget. Ownership and building management were pleased with the results. CBRE reported positive feedback from tenants following the completion of the project. Working closely with the manufacturer, an extended warranty on both the new waterproof membrane and paver system was offered to the owner upon completion.