Many prestressed concrete parking structures have been built and some have generated many problems. These problems have arisen because the engineer, architect, and contractor too seldom realize that a parking structure is a different type of building than they normally build due to its exposure to environmental and weather changes- not only moisture and temperature but also corrosive agents. A parking structure may experience temperature differentials of up to 160 degrees F, severe drying by the wind, and severe freeze-thaw conditions with ice, rain, snow, and corrosive deicer salts. The "crack-free" aspect of prestressed concrete lends itself well to the owner's desire for a maintenance-free deck. With cracking controlled, leakage throughout the deck is eliminated, thus preventing deterioration of concrete, corrosion of reinforcement and marring of automobile paint finishes. Concrete is a durable material; prestressing it adds the crack-free, long-span characteristics needed to produce the optimum parking structure. It is essential that rain and snow-melt water run off a deck quickly so they are unlikely to cause deterioration. Deck slopes of one-fourth of an inch per foot are desirable, with one-eighth inch per foot being an absolute minimum. In no case should a parking deck be flat or level. Not only should the floors have positive slopes to the storm water drainage system but also the drains should be set 1 inch below the finished floor elevation. Nonferrous metal or at least galvanized metal should be used for all accessories in the concrete which are exposed prior to erection or after the installation is finished. Also, any cold joint must be waterproofed with a high-quality sealant or seepage will eventually cause deterioration of the structural connection. With proper awareness of the potential problems, the designer and contractor will be able to take the steps necessary to build their client a successful parking structure.