Published: Jan 1998
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A proposed leak repair scheme (tested per ASTM) could have significantly altered the aesthetic appearance of a 42 story, 600 ft. highrise office tower and adjacent lowrise auxiliary buildings in San Francisco, California. This case study describes an alternative leak repair scheme for the 1000+ panels of porous stone faced precast panel window wall, the objective of which was to retain the existing building appearance to the maximum extent feasible.
Water from panel perimeters, panel cracks, and stone anchor locations was leaking into the building around the windows and other areas. The remedial solution presented here focuses on the water in the cavity bounded by the porous stone faced pre-cast panel, the flush mounted aluminum and window frame, and the exterior and interior silicone sealant joints. The design methodology consisted of first minimizing water infiltration through the porous stone in a visually unobtrusive manner and second, channeling and controlling the remaining infiltrate to both the existing weep system and into newly created weeped jamb cavity reservoirs.
This option was implemented from the exterior, (using the building's window washing rig) on a mid-height in-situ panel, (selected for testing due to prior leak history). Readily available construction materials and methods were utilized. Upon completion, the repaired panel passed an extended duration ASTM E-1105-93 test. Substantially reducing water penetration into the composite panel and then controlling the remaining infiltrate, this ASTM tested leak repair option provided a functioning, cost competitive solution to the water intrusion problem without altering the existing building aesthetics.
porous stone, precast panels, parged, silicone sealant, jamb cavity reservoirs, weeps, leaks, water intrusion, window wall system, bond breaker
Senior architect, Ian Mackinlay Architecture, Inc., San Francisco, CA