Foundation Wall Waterproofing Repair Strategies for Existing Buildings: The Long-Term View

Approximately half of all of today’s commercial and institutional buildings were built before 1980. Many of these buildings were conceived and designed for generations of use, but have outlasted, or will soon outlast, the functionality of their below-grade waterproofing systems. In the authors’ experience, competent below-grade waterproofing systems generally have a service life of 40 to 50 years before remediation may be required. Deteriorating or failed below-grade waterproofing systems will begin to allow leakage into below-grade foundation walls and adjacent interior spaces damaging interior finishes, disrupting building operations and causing deterioration of structural components. Where below-grade building spaces consist of unfinished areas, such as parking decks or mechanical spaces, some leakage may be tolerable, but buildings with finished below-grade spaces require remedial waterproofing repairs to address leakage. In other cases, owners are purchasing buildings with the desire to repurpose previously unoccupied below-grade spaces, and remediating water infiltration through below-grade foundation walls to address leakage or to meet the changing performance demands presents significant technical and logistical challenges. This article discusses remedial waterproofing strategies for foundation walls.