Proactive Waterproofing

March 30, 2007
Publication: Concrete Construction p 36-43
Author(s): Kenneth Klein

Abstract: Waterproofing below-grade foundations is straightforward in principle but difficulties can come up during application. This article focuses on issues related to waterproofing foundations in below-water-table construction that is close to the property line, although most of the principles apply equally to other below-grade structures.|Most of the problems that arise in waterproofing are due to one or more of the following:|-The owner expects a watertight subterranean space but wants to limit spending on a building component that has no aesthetic impact|-Designs that are inappropriate for the field conditions|-Choosing inappropriate waterproofing membranes for the proposed wall casting methods|-Heavy construction methods that damage waterproofing materials|-Lack of access after completion to implement repairs|-Construction schedules that do not allow proper sequence and adequate inspection of the work|The project team can solve these problems by considering four important aspects of design and installation:|-Designers must understand the owner's expected level of performance. If the owner expects absolutely no water entry, then the design must be developed accordingly.|-Contractors must understand the work requirements for the below-grade waterproofing components and sequence the work with a schedule that includes adequate time for inspection and repair.|-Designers must specify materials that are appropriate for the intended use.|-Waterproofing subcontractors must supply the appropriate workmanship for the intended system and confirm that the installation meets the project requirements.|The proactive approach, therefore, starts with the owner's performance expectations. Often the conversation with the owner is limited to the basic level of performance. The owner does not recognize that "no water entry" requires a design with more than the minimum number of details and some level of redundancy. Owners must be educated so that they can define the expected performance level and accept the construction costs needed to achieve it.