Building Up

It was the end of the first World War. Model T Fords roamed the roadways of America, clogging the streets of the United States’ largest population centers and inducing headaches for city planners and travelers alike. Municipalities used various measures to address the problem. The city of Chicago even banned downtown parking altogether for a time.

The problem led famed Chicago architects William Holabird and Martin Roche, when building Chicago’s Hotel LaSalle, to try their hand at an up-and-coming approach to parking architecture—the stacked parking garage. The team innovated on the structure, creating a five-story system of ramps and elevators for moving cars from floor to floor. Completed in 1918, the Hotel LaSalle Garage came to be known as “America’s finest garage.” It would serve the city for some 87 years before finally being retired in 2005.

If Holabird and Roche’s idea was a good one in 1918, it’s a great one today, as the population of the United States has exploded and property values across the country—not just in major cities—has reached a premium.

Nowhere is this truer than in the congestion of the northeast, where Blakeslee Prestress manufactures precast concrete members for structures from Boston to New York. “In the northeast, as you might imagine, there’s not a heck of a lot of land left,” says Bob Vitelli, senior vice president. “So whenever they build anything, most of the time they have to build some kind of structured parking.”

Not Your Grandfather’s Parking Structure Parking structures have done a lot of growing up since their infancy in the days of Holabird and Roche. The general concept—building parking vertically instead of horizontally—hasn’t changed, but methods, materials, and appearances have.

Over the years, parking structures have increased in levels as well as in total square footage. Improved building methods and materials have made it common to find structures taller than 10 stories and larger than 1.5 million square feet. Along with size increases, parking structures have also become more navigable for motorists as column placement has widened, opening sight lines and decreasing parking hazards.

While design and material improvements have increased the physical spans in parking structures, builders have also found ways to extend their life spans. Many of these improvements address the bane of the parking structure’s existence—corrosion, which is most often brought on by chloride penetration from deicing salts. Concrete admixtures, epoxy-coated reinforcement, stainless-steel joints, and waterproofing have all been deployed to minimize concrete’s vulnerability to corrosion. In precast structures, wider tees developed in recent years have meant fewer joints, which are the major source of maintenance issues.

Designs over the years have come to focus more and more on the end-user, says Vitelli. “There is more lighting. There is better drainage. There is more security. There is more openness. Those are the things that over the years we have learned that the market is looking for.” Another benefit to the end user is the trend to integrate the parking structure into the retail, housing, and office buildings they support. This improves access for the user and makes better use of the property.

The marketplace has also pushed developers to shed parking structures’ historically crusty, unfinished look for a more dressed-up appearance. Planners want parking structures to blend with the overall look and feel of the community, and developers don’t want ungainly parking structures to detract from the buildings they support.

“Neighborhoods do not want structures that look like parking decks,” says Bob Hassey, vice president of sales for J. W. Peters, a precast-concrete manufacturer based in Wisconsin. “We have done structures recently that look like retail streetscapes. Structures are getting much more aesthetically pleasing, so they fit in the neighborhood.”

To spruce up the parking structures’ exteriors, the industry has developed a broad palette of approaches that includes brick veneers, pigments, and surface treatments. Taken together, these developments inside and out have made for parking structures that better serve developers and the eventual users. The Great Debate

While few members of the industry would question the value of using concrete in parking structures, there’s no end to the debate about what method of building is best. The disputants generally fall into two camps based on their preferred method—cast in place or precast. Those who favor cast-in-place construction cite the versatility and convenience of pouring the concrete on location. Because members do not have to be hauled to the location from a plant, spans can be longer than what would fit on a truck.

Using a post-tensioned system for reinforcing the concrete slabs and materials, cast-in-place structures also require less depth of cover, meaning less concrete is required and costs are therefore lower. Less cover also opens up additional headroom to meet code requirements and requires less excavation for below-grade structures.

Post-tensioned structures also have the benefit of being relatively resistant to corrosion by having minimal cracking and no exposed joints to maintain. And the cast-in-place approach creates a monolithic connection between slabs, beam, and columns that stands up well to other loads. Proponents of the precast method note the virtues of manufacturing concrete in a controlled environment. Because they are not at the mercy of the seasons, precasters can pour concrete year round in ideal climate conditions. This makes precasting particularly desirable in climates that experience wide fluctuations in temperatures.

They also argue that, because there is no form to set up and remove and no curing time on site, precast concrete leads to quicker construction and lower building costs. And they assert that having pretensioned reinforcement makes for a more durable structure overall, leading to long-term savings. D

espite the unyielding nature of this debate, it is not a situation where never the twain shall meet. In fact, one approach to parking structures is a hybrid of the two. In this approach, precast members are used to create a skeleton to support cast-in-place floor slabs. On the Rise Regardless of the building method they espouse, constructors of parking structures agree that the market for parking structures is strong and only going to grow.

“The potential for growth is good,” says Jay Cariveau, director of business development and marketing for Metromont Corporation, a precast-concrete developer in the southeast. “The growth will be driven at numerous levels—from municipal and institutional owners who master plan for future growth to developers and owners in urban and suburban markets who understand the features and benefits of cost-effectively incorporating parking into their projects. It’s about the people and users, making their experience safe and enjoyable.”

Vitelli has seen the same trend in the northeast, where the community is planning a series of parking structures at rail line stops to help alleviate traffic along the “one big traffic jam” that is I-95.

While these industry experts are reluctant to predict market specifics too far into the future, they say that the conditions that have contributed to the current demand for parking structures are not likely to go away.

“I think the trend we have seen over the recent years will continue,” says Hassey. “As property values soar, owners want to make optimum use of every bit of property they have.”