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.
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.