Allana Buick & Bers (ABB) performed building envelope evaluation of issues with newly finished office building and a forensic case study of waterproofing failure of the Sunnyvale Towne Center in Sunnyvale, California. The study was performed for a construction defect litigation case where a bentonite/HDPE composite system was installed and had failed. The project is the 2nd largest below-grade structure in Northern California with six stories above grade, four stories below grade, two of which were below the water table. Additionally, this project was the largest below-grade waterproofing repair of its kind in California.

The structure experienced extensive leakage throughout the perimeter walls in the below-grade parking levels. The structure was built on zero lot line with shotcrete foundation walls placed against wood lagging and soldier pile retention walls. The study included performing core sampling through the 18” thick shotcrete walls, partial excavation, review of construction drawings, review of lagging installation and soil consolidation, visual observations of leaks and water testing.