A plaza system is any supported slab that provides greenscape, tree planters, or vehicle and pedestrian movement over occupied space. A unique defining characteristic is the waterproofing requirement over occupied space, which at some level in the plaza system interfaces with the wearing surface and/or greenscape or tree-planters, to produce high potential for distress, membrane leaking, and/or plaza surfacing degradation.

Plazas are subject to some of the most accelerated and vigorous deterioration and distress of any building system. Harsh exposure conditions from moisture, thermal effects, weathering, and traffic often reduce these systems serviceability at a rate even surpassing that of parking and bridge deck structures. Accordingly, special evaluation and design of plazas should be performed.

Carl Walker’s plaza restoration evaluation approach includes a review of existing documents, a detailed evaluation of the plaza system to determine if there is leaking or deterioration excavations to review the type/condition of membrane waterproofing, and recommendations for repair options. Our evaluation reports identify the root cause of deterioration and present practical, cost effective repair options based on our extensive experience.

Carl Walker provided the National Institute of Building Sciences (NIBS) design guidelines for below grade waterproofing and plaza systems. Our design guideline chapter was part of a larger Whole Building Design Guide effort sponsored by the GSA, State Department, Army Corps, FEMA and various other federal organizations. This chapter is one of the first thorough works that provides guidelines on proper plaza design. 

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