ABSTRACT
Waterproofed plaza systems differ greatly from roof systems in their performance criteria. In conventional roof systems, the weather-exposed membrane must resist ultraviolet degradation and extreme temperature variations. A waterproofed plaza membrane experiences far less temperature change and is permanently shielded from ultraviolet radiation. As an example of possible plaza live-loading, the service weight of a small, two-axle fire-fighting pumper can exceed 26,000 pounds in concentrated wheel loads. Post-tensioned slabs offer better control of deflection and cracking within the plaza deck. Careful analysis of the deck deflection pattern and post-tensioning design is critical to achieve proper slope to drains after the plaza overburden has been placed. Composite decking comprised of concrete on steel centering is more commonly used for terraces at higher floor levels than for plaza design near grade level. Plaza drainage should minimize saturation of the wearing course, which might disintegrate from freeze-thaw cycling.
