Architects hunting for construction treasure get lucky, find rare stone

When the Catholic University of America decided to construct a new nursing school, the architects faced a major obstacle: The stone found at other buildings on the Washington, D.C., campus that first opened in 1888 wasn't available.

So, the designers went hunting and found what they were looking in another now-demolished building. Except the stones were too large. That led them to a solution they believe can be used regularly on future projects.

From pre-World War II high-rise apartment and condo towers in New York City to cathedrals and schools, buildings are clad in stone to convey a sense of substance and stability. But the right type of stone can sometimes be hard to find, as well as more expensive than brick, glass or steel.

Catholic University hired Robert A.M. Stern Architects to lead the project because the New York-based firm is known for its expertise in traditional architecture and the use of stone as a building material. The portfolio of work compiled by RAMSA, as the firm is also known, features two high-profile projects under construction, the St. Regis Residences in Miami, and 350 Boylston St., a Boston office building.

RAMSA almost immediately discovered that not only was the stone found at most of the buildings throughout Catholic University’s campus in northeast Washington not readily available, but also their regular stable of stone suppliers came up empty.

It’s possible to manufacture artificial stone to look like a certain type of rock, according to Tony McConnell, senior associate at RAMSA, but Catholic University didn’t want something that would look fake. So the designers kept searching.

“To try to copy the existing stone on campus would not have provided a look that we were interested in,” McConnell told CoStar News.

They got lucky. They discovered Transfiguration of Our Lord Church in Philadelphia, built in 1924, used the exact same type of stone as Catholic University. The stone called Port Deposit Gneiss is named for its quarry near Havre de Grace, Maryland. The church had been demolished in 2009 and gneiss blocks salvaged from the church had been stored at a quarry in Delaware. RAMSA obtained the gneiss blocks to use for Catholic University's nursing school.

If the demolished Philadelphia church’s gneiss had not been identified, RAMSA “would have had multiple stone providers give us samples and we would have picked the one that was closest,” McConnell said.

“It would have been like trying to find a needle in a haystack,” McConnell added.

The journey still wasn’t complete, however. The salvaged gneiss blocks were too thick — between six and eight inches per block. RAMSA planned to install the stone on a precast-concrete backwall, but the blocks couldn’t be that wide.

RAMSA used a hydraulic stone splitter to break the gneiss into two parts, each about two inches thick. That size was suitable for the precast installation method. The cost of using a precast installation, where stone blocks are attached to concrete wall panels using mortar and mechanical anchoring, was about $3 million to $4 million cheaper than if the stone blocks had been laid by hand. That savings helped offset the added cost of splitting the large blocks.

High Concrete Group in Denver, Pennsylvania, was the precast concrete contractor.

The 102,000-square-foot Conway School of Nursing building, situated on Michigan Avenue, opened last year and features classrooms, simulation and clinical labs and student gathering areas.

“We rose to the challenge of designing a building that looked and felt like it had been there as long as its late 19th and early 20th century campus neighbors,” Jennifer Stone, a partner at RAMSA, said in an August statement from the architecture firm.

The largest Catholic church in North America, the Basilica of the National Shrine of the Immaculate Conception that opened in 1913, is located on the Catholic University campus.

McConnell expects that RAMSA will take the lessons learned from the nursing school project and apply them to future projects, especially with commercial clients who increasingly have requested buildings with stone exteriors.

RAMSA has used the hydraulic stone splitter to create thinner blocks of stone at other projects in higher education, including buildings for Colgate University in Hamilton, New York; Marist University in Poughkeepsie, New York; and Villanova University in Villanova, Pennsylvania.

Distinctive buildings have their own stories. Snapshots is an occasional feature showcasing one of them.