Drainage: The Essential Ingredient in Basic Parking Structure Durability Design

Parking structures are constructed of concrete and steel and are essentially exposed to the elements. As such, they have a life cycle similar to that of a highway bridge. A parking deck can be exposed to rain, snow, extreme high and low temperatures, road deicing salts, and just about anything else that can cause deterioration in an exterior environment subject to vehicle traffic. The deterioration typical in parking decks can be attributed primarily to water. Standing water will accelerate deterioration, especially if it is contaminated with road deicing salt. If the standing water freezes, it represents a hazardous condition for both pedestrians and vehicles. To counteract the problems caused by standing water, a well-designed drainage system is essential. A brief explanation of the deterioration mechanisms typical in concrete parking structures is presented herein, along with suggestions to mitigate deterioration. The focus of the discussion is excellent drainage, which is generally the most effective and least expensive durability feature that can be incorporated into a parking structure design. Excellent drainage design is not a simple proposition and is often overlooked. This can lead to the necessity of expensive repairs in the future. Finally, suggestions for designing excellent drainage are discussed, incorporating guidelines from, among others, the American Concrete Institute, the National Parking Association, the American National Standards Institute, and extensive personal experience.