Building around tradition

Building a 21st century world class art center in the middle of a 19th century Southern-style neighborhood means looking at construction in some very non-traditional ways.

by Clair Urbain

The rich architectural tradition in Savannah, Georgia, makes this city unique. Built when cotton was king in the Delta, the city works hard to maintain the flavor of the 18th and 19th century buildings while adapting them to the 21st century world.

When the Telfair Museum of Art proposed building the 64,000 sq. ft., $26 million Jepson Center for the Arts in the heart of Savannah’s historic district, it met with some critical eyes from the Historic Review Board, which is charged with maintaining the look and feel of Savannah.

After several design changes and fastidious attention to detail that allows the facility to attract world-class exhibits, the plan on paper can best be described as complicated.

That’s the first word out of the mouth of the project’s general contractor Walter B. Murphy III, president of Rives E. Worrell Co., Inc., as he describes the project. As general contractor, Murphy’s company handles the concrete and carpentry work and coordinates other work with subcontractors he hand picked for this high profile job. The building, approximately 20 percent complete, will open in early 2005.

“This is one of the most complicated buildings ever built in the Savannah area. It has many geometric curves in the design and has over $2.5 million of glass in the walls and the roof. It’s actually two buildings that are connected by a bridge that spans a lane,” he says.

World-renowned architect Moshe Safdie and Associates designed the museum, adapting original plans to answer the review board’s objections. While blending into the city’s historic urban architecture, it features vast open areas that rely on light and shade to create an interesting environment for exhibits. Cream-colored Portuguese limestone and architectural concrete help tie the building in with Telfair Square and neighboring 19th century buildings. The facility has gallery space, two auditoriums, educational galleries, offices, a library, sculpture gardens, a museum shop and a café.

Complex construction
The curved, skewed walls and exceptional use of glass in walls and skylights presents interesting challenges to builders.

“The two buildings start at different elevations. There is a 2' 8" difference in elevations, but the coursework of the walls must line up and finish at the same height,” explains Murphy. “Because of the curves in the design, there are some very large radii that make construction difficult. Up, down and all-around, we must be sure we are exact.”

To assure accuracy, site engineers established several control points on the site. A reference point across the street on Telfair Square also helps double-check all measurements.

The structural steel, immense by most building standards, carries the spans needed to create an open, flowing environment. The three-story buildings will have concrete floors; walls will be windows or limestone veneer on concrete.

“The limestone will be quarried in Portugal, cut in Italy and loaded onto cargo containers that will be delivered to the Port of Savannah. The Italian stone cutter is only one of three companies in the world that can cut the limestone to the specs we need,” says Murphy.

Once the structural steel and concrete floors are in place on each floor, Harold Swailes, the project superintendent, will use templates made from 3/4" plywood to maintain layout accuracy.

“I went to a large parking lot and laid out the radius curves onto plywood. The longest template was 190'. There are many different radius walls coming together in this design. The roof has a 221' radius; another radius is 199', which becomes a 105' compound radius that meets up with another that is 65'. To further complicate the building layout, the inside wall of the three-story main lobby skews inward.

“If we didn’t use a template, we would be measuring all day. The template is the best way to physically do it and keep it accurate,” Swailes says.

The architectural concrete used on the façade entrances offered Swailes and his crew some challenges. “It’s all cast-in-place and has no forming penetrations in it. It’s a totally different forming system from what we use in conventional concrete work. The concrete is also five times as expensive, so it takes some attention to make sure it comes out right,” Swailes says.

To achieve the smooth, penetration-free face, the forms are made of Finn-form plywood that is smooth on the inside and coated with a release agent. All corners have gaskets that seal the form, and 2" x 8" whalers clamped around the form hold it in place. Once poured, the concrete is vibrated extensively for a smooth finish.

The design calls for a joint line every 4' in the wall face that will align with the stone courses. To accomplish that, Swailes and his crew used 4' x 4' plywood sheets separated by a working joint to create a mortar-joint effect. “The concrete consultant checked out the work and says it is some of the best architectural concrete that he has seen in this country,” Swailes says.

Space challenges
The building’s open, airy design provides little space for mechanicals and strict fire protection requirements makes this one of the most unique and challenging projects that Everette I. Boaen, president of Boaen Mechanical Contractor, Inc. and his crews have ever worked on.

“We are in charge of the HVAC portion of this job. It’s a $1.6 million job that uses some very interesting methods for fire control and air movement,” Boaen says.

Sultry Savannah weather makes temperature and humidity control critical, says Boaen. “There is triple-redundancy on all controls. The museum requires that humidity be controlled to 55 percent, plus or minus five percent at all times. The system used in this building is the same design used by the Peabody Museum in Philadelphia and the Smithsonian Institute.”

Fire control systems are also complex. Because sprinkler systems could damage artwork, the museum is outfitted with a dry fire-suppression system.

To control smoke damage, the building is designed to be super-ventilated during a fire. “The dry fire suppression system will put out the fire, but the positive ventilation system will get the smoke out quickly,” Boaen says.

“In other buildings, fire dampers shut down air flow in the HVAC system if there is a fire,” says Ed Shuman, Boaen’s on-site project superintendent. “In a fire, this system shuts down the HVAC system and uses two high-cfm fans to move air through the HVAC ductwork and into the building. Then, 11 exhaust fans installed in the roof quickly pull the smoke out of the building.”

The ductwork, made with heavy-gauge metal, is insulated with two layers of fire wrap that offer 2,000 F protection for two hours. “This is the same material used for zero-clearance exhaust hoods. It’s very expensive, but allows us to meet the zero clearances needed in the building’s design,” says Shuman.

To maintain the open design of the building, ductwork often penetrates the structural steel. “The structural steel is prefabbed with duct and other openings in place. We build all of our duct work and connections off-site based on the engineering drawings, and in the case of the mechanical room, they gave us an allotted amount of space and told us to figure it out. In many ways, this is a design-build type of job for us,” says Shuman.

“We have been prefabbing most of our piping work off-site for several years now,” says Boaen. “At first, some of the workers didn’t think it was possible, but when we were able to set air handlers and pumps in two or three hours instead of two or three days, they became believers in prefabbing piping off-site.”

“Space on the jobsite is very tight,” adds Shuman, “Prefabbing makes the most sense here. We don’t have room for a jobsite trailer, much less any room for a fabrication area.”

Trades work together
The buildings’ designs leave little room for any trade to make a mistake, so the trades must work together to get the job done.

Although it can be a challenge, Shuman says the continuous contact with other subs and the general on the job has prevented problems.

“I produce the shop drawing and share it with the other contractors. We discuss where we have problems and solve them before they happen. We double-check each other’s work and formally meet every two weeks on the project on concerns. We have very good communication among all of the trades.”

Even with the complexity of the project, Murphy is pleased with the progress. “This is a high-profile job and the job is going well because contractors working on it were chosen because of their reputations. The high quality of subs on the job and their workforces are paying close attention to what they are doing. Many times, workers don’t take an interest in what they are doing. That’s not how these guys approach their work, and it shows,” he concludes. 

Published in the July/August 2003 issue of Contractor Tools and Supplies magazine.

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