Project: High-Rise Office Tower
Clients: Bronson, Bronson & McKinnon LLP
Location: San Francisco

A 42-story office tower in downtown San Francisco developed numerous leaks during winter rainstorms shortly after the building was completed. Expert investigations uncovered several sources of water intrusion in the building curtain wall, composed of more than 1,000 rectangular, stone-faced, precast concrete panels, each with a window in the center.

As a result of the preliminary investigations, the building owner planned to replace the entire curtain wall at a cost of more than $8 million, and he wanted the architect, the contractor, and subcontractors to share the expense.

The architect hired IMA to determine who was responsible for the leaks and to develop a less expensive repair scheme. By examining construction records and previous reports by the plaintiff’s experts, IMA determined that construction problems, not design defects, caused the leaks. IMA Senior Architect Richard Flood then devised an alternative repair solution for the curtain wall that could be implemented with simple power tools from the building’s window-washing platforms, and wouldn’t require replacing the curtain wall panels or closing adjacent streets.

The cost of the alternative repair was less than $4 million and the case settled before going to trial. The retrofit passed extensive tests conducted by experts working for the building owner.

Related article

Flood, Richard S. “Remedial Repair Leak Prevention in Porous, Stone-Faced, Precast Panels—A Case Study Option,” Water Leakage Through Building Facades, ASTM STP 1314, R.J. Kudder and J. L. Erdly, eds., American Society of Testing and Materials, 1998.

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