Jones Lang LaSalle
The thirty-five-story office tower and low-rise annex was the headquarters for National City Corporation during the project and now serves as the Cleveland-area offices for PNC Financial Services. Skidmore, Owings and Merrill designed the center, and construction was completed in 1980. The center has several roof levels totaling 37,500 square feet. At the time of WJE's initial assessment, the original fluid-applied membrane waterproofing system remained in place over a cast-in-place concrete roof deck. The waterproofing membrane was covered with two inches of extruded polystyrene foam insulation and three-quarters of an inch of crushed stone roof ballast.
WJE's investigation included a detailed condition assessment of the roofing system and window washing tie-back anchors to determine the remaining expected service life; development of waterproofing repairs and replacement alternatives; and preparation of the construction budget and schedule. WJE then assisted the owner in prequalifying waterproofing contractors prior to bid the work; and provided construction period services, which included field observation during the construction, testing and certification of the window washing tie-back anchors and roof carriage tie-down anchors, and contract administration. Design challenges included the need for a temporary external elevator that was mounted to the tower, night construction to minimize disruption to the office tenants, redesign of the window washing tie-back anchors and roof carriage tie-down anchors, replacement of the waterproofing system and deteriorated concrete window washing runway. The new waterproofing system consists of a protected hot fluid-applied membrane assembly with interlocking concrete pavers instead of crushed stone ballast to resist the wind uplift forces.