The historic National Constitution Center combines dimensional stone and StoneLite® natural stone composite panels to create a modern-classic aesthetic in the heart of Philadelphia.
Project name: National Constitution Center
Project location: Philadelphia, Pennsylvania
Architecture Firm: Pei-Cobb Freed & Partners
General Contractor: Turner Construction
Exterior Product: StoneLite® Chelmsford Granite, Indiana Buff Limestone
Amid the abundance of rich history, Philadelphia adds another memorable landmark to its historic landscape. After becoming a distinguished patriotic city in 1701, Philadelphia has hosted many significant assemblies including the drafting and signing of the Declaration of Independence and the Constitution. Also home to the Liberty Bell and the first American flag, Philadelphia proudly hosts another monument to the city, the National Constitution Center. The 285,000-square-foot building is the first museum devoted to honoring and explaining the U.S. Constitution.
Officially opening on July 4, 2003 at the north end of Independence Mall, the National Constitution Center underwent approximately 27 months of construction under the architectural direction and design of Pei-Cobb Freed & Partners. The exterior facade boasts a modern-classic aesthetic, using dimensional stone and lightweight composite stone panels manufactured by Stone Panels, Inc.
The unique design was dreamed up by Henry N. Cobb and partner Ian Bader, along with exhibit designer Ralph Appelbaum. Although veering away from the traditional red-brick found throughout the neighboring structures, the building’s design was applauded by prominent architectural critics. Soft tones of Indiana Limestone, broken up by 8-inch-high bands of light gray Chelmsford Granite, create a modest design that complements the surrounding environment.
Enriching the stonework is a two-story glass entrance, referred to by Cobb as the “front porch.” According to Cobb, the overall building design couldn’t be too official.
“It’s not a government building,” said Cobb. “Nor could it be extremely monumental, since it is neither a museum nor a shrine. It had to be more relaxed.”
Introducing the granite bands into the design of the exterior facade provided a less formal look, reducing the scale of the structure and emphasizing it horizontally.
As is often the case, executing the project on time and on budget was a concern to the architects and owner. In order to combat this challenge, project architect, Craig Dumas, had to find an alternative to the facade design they initially proposed. As a result, an alternative solution had to replace initial plans for the interior design of the two-story lobby.
“Originally, we designed the walls to be solid stone,” said Dumas. “When the drawings went out to bid, it was a ‘hot time’ on the market, so we had to cut costs.”
The general contractor, Turner Construction, proposed using StoneLite® panels, a lightweight stone alternative, to significantly cut costs on installation.
The StoneLite® panels, fabricated from the same Select Buff Limestone and Chelmsford Granite used on the exterior, also decorate the interior lobby. The lightweight solution, at only 3.5 lbs. per square foot , allowed a low-cost installation for the exterior and interior applications.
StoneLite® panels are an alternative to solid heavy stone. The solid rough-sawn slabs of limestone are sandwiched between two ¾-inch-thick pieces of aircraft-quality aluminum honeycomb by adhesion using a proprietary high-strength, fiber-reinforced epoxy. to create a flexible and durable solution to dimensional stone.
The patented manufacturing process offers substantial impact resistance and unmatched flexural strength. The fiberglass skins directly behind the stone provide an impermeable waterproof barrier, which eliminates the need for a secondary water barrier.
The exterior and interior facade showcase StoneLite® Indiana Buff Limestone panels broken up by 8-inch bands of StoneLite® Chelmsford Granite panels. The average panel size was 5’ by 3’4” but the pieces only weighed 60 lbs. Some panels were fabricated to various angled corner shapes, while others to a convex- or concave-curved shape at a fraction of the dimensional stone cost. Approximately 20,000 square feet of StoneLite® limestone and granite was installed on interior walls and 9,000 square feet on the exterior.