Airport Renovation Case Study

Project: Charleston International Airport Terminal Redevelopment Project
Location: Charleston, South Carolina
Architect: Fentress Architects

The Project: The old Charleston International Airport terminal was built in the 1980s, long before electronic check-in or even wheeled luggage. The airport’s look and functionality have not changed much since then, while its traffic volume has grown at twice the industry average. By 2016, it had already reached the numbers projected for 2025. In response, the airport's Redevelopment and Improvement Program was initiated in order to meet the growing demands by radically improving the existing structure's functionality and design.

The Challenge: As a busy airport, the renovation project needed to maintain airline operations and ensure safety while accommodating 15,000 passengers per day. A key concern revolved around the fact that about 70 percent of the floor was brown clay brick pavers; the rest was carpet. The overall effect was dark and dingy. The Charleston County Aviation Authority wanted to change more than just the appearance of the floors. Bryan Smith, AIA, PE, LEED AP, part of the project team from Fentress Architects in Denver, recounts, “The first thing we heard from the client was, ‘No more clickety-clacks!’” Meeting that day in the airport's board room, they could hear each clickety-clack of innumerable luggage wheels passing over the bricks out in the concourse. Another concern was the budget for the program, considering the extensive renovations that were planned to include new mechanical, electrical, and IP systems.

The Design Solution: The Aviation Authority worked closely with the Fentress team to recreate the facility's functionality and aesthetics, starting with the floor.

The architecture team addressed the client's demand for smoother, quieter, and more attractive flooring by proposing terrazzo as a seamless surface. “We pushed to enhance the design and colors, to bounce the natural light and keep it bright,” Smith says. Though terrazzo was initially a material choice for the main public areas because of its seamless finish for wheeled luggage, it also provided the design flexibility to capture the city’s distinctive character with a contemporary design. Open expanses and floor-to-ceiling glass walls bring in abundant natural light and offer travelers a clear view of airfield landings and liftoffs.

“Terrazzo was a big part of the redevelopment design,” Smith shares. “We could not have pulled it off with any other flooring.” The terrazzo in five colors with mother-of-pearl, glass, and marble aggregates throughout the concourses was designed to represent the traditional gardens in Old Town, Charleston; other patterns recall the planks of the city’s oceanside docks. “Carpet would not have had the same effect and quality,” Smith adds, noting that terrazzo is “a cleaner material” and more easily maintained than carpet, which can hold moisture and dirt.

The Renovation Dilemma: The initial expectation was that the old brick floor would have to be demolished and removed, including 2 inches of substrate, and then built back up again. However, according to John Wingo, senior project manager with David Allen Company of Raleigh, North Carolina, the terrazzo contractor on the project, removing the brick pavers and rebuilding the substrate was a prohibitively expensive proposition. The pavers would have had to be jack-hammered out—a noisy, messy, and labor-intensive process. “And you never know what the concrete is like underneath it,” Wingo adds. If the mortar bed was found to be installed over an inferior substrate, dealing with that would have been yet another messy and labor-heavy obstacle. Wingo estimated the costs for taking out the original floor to be a minimum of $200,000. Then, the price to fill the floor back up to elevation with a mix of epoxy and sand aggregate (a relatively inexpensive option for the fill) could be about $1 million.

It soon became apparent that a terrazzo installation based on demolition would not be possible within the established budget. “We were pressed up against the ropes to keep terrazzo in the project,” Smith explains. Then, through information from the the National Terrazzo & Mosaic Association (NTMA), the team learned that terrazzo can be installed over several different floor systems under the right conditions. I was delighted to discover that that the project fit these parameters. (See NTMA's “This Old Substrate” article, available at bit.ly/3yGWboP.) “Being able to do that is what opened the door and made the project viable within budget,” Smith says. “It meant a ton of cost savings.”

The Renovation Solution: NTMA’s Technical Advisor Gary French worked with the project team and made recommendations for flooring preparation. Before installing the terrazzo, bondability tests were conducted to ensure proper adhesion to the 1.5-inch clay brick pavers. “The first simple test is to examine the floor for cracking,” Wingo explains. This job had zero cracks in the brick pavers, which had been installed on a 1.5-inch mortar bed. Cracks could indicate a loss of bond and possibly a sign of drastic movement that would indicate a structural problem. Further low-tech tests included dragging a chain across the floor, tapping it with a pipe, and even bouncing a golf ball to listen for hollow points. The crew sounded it out, cored the existing floor to check for adhesion, and found it to have a solid bond. “No loose pavers were found; it was an exceptionally well-installed job,” Wingo says. The team also checked for relative humidity in the concrete by coring the concrete substrate with the ASTM F-2170 Protimeter Test. The floor passed the test, but the team put down a moisture treatment over pavers as a precaution.

To prepare the substrate, the pavers were treated as a concrete slab and shot blasted to rough them up before the moisture treatment was applied. A slurry coat—an ultra-thin layer of epoxy resin and sand—was then applied to the surface to smooth out any uneven pavers and grout joints, followed by a 100 percent elastomeric membrane. The floor was completed with the application of ³⁄₈-inch epoxy terrazzo.

The Project Management: The airport remained fully functional during the renovation work. Accordingly, the terrazzo installation was broken down into 30 phases and subphases, with night work and tiny areas of work sectioned off where necessary to allow for the safe flow of the public. Ultimately, approximately 125,000 square feet of epoxy thin-set terrazzo was applied, some in new construction areas, such as the security checkpoint and a portion of Concourse B. Primarily, terrazzo was installed in existing structures over concrete slabs or brick pavers in the main circulation areas: ticketing hall, central hall, baggage claim, and restrooms.

In addition to the total of $1.2 million to $1.5 million saved by the option of pouring terrazzo over the existing floor, Wingo also credits it with slashing several months off the schedule. Work phases were tightly segmented in the busy concourse; workers shared space with airport employees and other trades as well as travelers. Foot traffic was continually rerouted and gate numbers reshuffled. “If floor demolition had been added simultaneously, it would have exponentially drawn out and complicated the work schedule further,” Wingo says.

The Environmental Solution: The environmental impact of the waste that removing the brick pavers and mortar would have generated represents another unique advantage. “Debris was kept out of landfills, and the dust that would have been kicked up was kept out of active passenger areas,” Smith notes. The Aviation Authority opted against pursuing LEED certification on the project because of the $1 million or more that managing certification would have added to the expenses. Fentress took the initiative, however, to include LEED language for terrazzo in the project specifications, including low-VOC and recycled-content requirements.

The Results: In Charleston's redeveloped and improved airport, the terrazzo is a unifying element for the airport's various spaces and functions, flowing seamlessly over the different substrates, which are now hidden. The floor reinforces the design concept as the colors and patterns carry the passenger from the curbside to the gate and back. The completion of the renovated and expanded airport was celebrated in October 2016, without a single canceled flight or any slowing of growth, and with further expansion of the airport still on course. The airport's 2.3-acre terrazzo installation won a 2018 Honor Award from NTMA for its design, craftsmanship, and impressive scope of work. “We were able to transform the passenger experience and make it feel like a new airport,” Smith concludes.