Plaza waterproofing is precarious because of the severe service conditions imposed on the system and the inaccessibility of the waterproofing membrane for repairs. Most systems are covered by a wearing surface that often impedes the drainage of water at the membrane level. The “buried” position of the membrane makes trouble shooting and repair difficult and prohibitively expensive.

This paper presents fundamentals for design and installation of plaza waterproofing systems. Of particular concern is the design of effective system drainage that facilitates the flow of water from the plaza surface, through the various components, and into drains at the membrane level. Adequate drainage is the single most important factor in the long-term performance of any waterproofing system. System design is discussed to establish the parameters for evaluation of specific system components: the wearing surface, insulation, drainage system, waterproofing membrane, building deck, and design of critical flashing details.