White added that Buildings 19, 21 and 24 were all designed to support the overall development of the West Campus as a cohesive plan. “Working with the buildings on the East Campus, the team of tvsdesign and RHF created a clear hierarchy of buildings that are organized around a main green space in a manner to make it easy to move around the campus on foot,” he explained.

Selecting the stone

Because Crab Orchard stone has been used minimally in some of CDC’s earlier buildings, White and his team decided to feature the stone throughout the design of the West Campus. Installed and sourced by Pyramid Masonry from Castle Rock Quarries, outside of Soddy-Daisy, TN, the Crab Orchard stone was utilized in a masonry application, so the pieces were fairly small blocks, and the largest pieces on a building were 1 to 2 square feet of face area. Larger pieces were used for the site walls — particularly for wall caps — ranging from 24 x 60 inches with a thickness of 4 to 5 inches.

“We decided to use natural Crab Orchard stone to create a unified appearance for both the new buildings and the landscape development,” said White. In addition, the landscape design extended its use throughout the campus in site retaining walls and perimeter fencing.”

With the changes in grade throughout the site, the retaining walls are prevalent, according to Rosen. “tvsdesign saw an opportunity to utilize the retaining wall idea as more than just sitework,” said the architect. “By incorporating the aesthetic into the bases of the buildings, the campus has a consistency. In some ways, it mimics more historic developments, such as hill towns where the use of locally quarried material for walls and paving reinforces something timeless about the site.

“As a material for buildings that are intended to provide 50 to 100 years of service, Crab Orchard stone has the benefits of reasonable cost, weathering well and requiring minimal maintenance over time,” Rosen went on to explain. “Since it has a rustic nature and color cast, it fits well in the naturalistic landscape concept required for this particular site.”

A cohesive design plan

In planning the building’s design, Rosen and his team had to consider the buildings on the East Campus, and how they were very different from one another. “The oldest projects were 1950’s modern buildings clad in beige brick masonry, but over time, other buildings introduced red brick masonry, precast concrete, exposed cast-in-place concrete and architectural composite metal panels,” he said. “We utilized some of these materials in the buildings, but the design decision was a process of editing and simplifying with a goal to create more cohesion to the campus.”

White added that some of the planners for the West Campus had suggested other types of stone for landscape use, such as granite, which is very common not only in Atlanta but also on the neighboring Emory University campus. However, Crab Orchard stone had the benefit of blending with the variety of architectural materials around the campus.

In specifying a color range for the project, Rosen and his team decided to limit the range quite a bit. Because the material is found in tones that range from gray to sand to pink, they tried to cull out the pink hues and utilize more of the tan and gray tones to complement the silver and green shades of the glazing systems.

According to the architect, mock-ups were also utilized for the veneer assemblies to make certain that the installation of the product with waterproofing and flashing materials was done properly. “There were also different treatments of the stone product,” said Rosen. “In some cases, we wanted a very natural dry-stack appearance. In others, we had the stone sawn and dressed for a more refined masonry appearance.”

Stonework challenges

Because the buildings have set the standard for development over a 10-year period, the client was involved in reviews at many levels. “We had aesthetic review by the Director of CDC and other senior staff, but also very close involvement from CDC’s Buildings and Facilities Office,” said Rosen. “Even the various offices and centers within CDC had an opportunity to review and comment on the materials in the projects. Our CDC project managers were very committed to delivering well-designed and good looking buildings for the personnel serving on the Roybal Campus and involving those personnel in the creation of their facilities.”

Investing an abundance of time on site to supervise the stone installation and monitor the work closely, Rosen noted there were some challenges involving the stonework. “The significant challenge in utilizing the material was reconciling the dry-stack look with the needs of the building enclosure system,” said the architect. “Since the stone and mortar are both very porous, we had to make certain the materials behind the veneer would properly drain water away from the building.

“Traditional stone masonry cavity wall construction leaves a gap behind the veneer for water flow downward, and then be channeled out of the building,” Rosen continued. “Since the dry-stack fills the gap behind the stone with mortar, we developed details that employed three-dimensional sheet drainage materials typically used below grade. This provided separation between the waterproof back-up wall and the stone material and allowed for flow down to the base of the building where it can be forced out of the wall.”

CDC Building 24, which measures just over 300,000 square feet, took about three years to complete — and has created a campus environment for CDC, which has been embraced by the organization. “Beyond the functional improvements that have come with the improvement in the organization of facilities, the quality of the buildings has also reduced maintenance and operations costs, which allows CDC to focus resources on their mission,” said Rosen. “As designers, we are excited by the recognition we have received from the CDC staff and management complimenting the project for reflecting CDC’s self-image as an agency focused on science and communications dedicated to public and environmental health.”