Cure and Conservation

by Jonathan McGaha | July 31, 2014 12:00 am

Proceed from a basis of knowledge. The concept seems simple enough, but it is nonetheless good advice. Architect Clay S. Palazzo, AIA, LEED AP, with Albany, N.Y.-based John G. Waite Associates, offers these words of wisdom to colleagues embarking on historical renovation projects. He speaks from experience after serving as the architect for the renovation of the Rotunda at the University of Virginia, Charlottesville.

“National Historic Landmarks, such as the Rotunda at the University of Virginia, deserve the highest degree of curatorial care and conservation,” Palazzo says. “Our approach involves the compilation of all known archival information, physical probes to expose underlying conditions and an evaluation of the physical evidence. The information is compared and contrasted, giving us the most complete understanding possible of the historic artifact. It is only then that the restoration and renovation can be planned and executed. Rigorous attention to methodology and detail result in a successful project.”

 

The History

In addition to being a remarkable structure, the Rotunda deserves attention because of its original designer, Thomas Jefferson. UVA was founded by Jefferson in 1819. His vision was for the library to be housed in the building because he wanted to create a campus centerpiece for learning, exploring, and interaction between students and faculty. Jefferson modeled his design-presented to the university board in 1821-after the Pantheon in Rome, and a tin roof was selected. Jefferson died in 1826 when the Rotunda was still under construction.

The tale of the Rotunda for the next several decades is filled with renovations, reconfigurations and reconstructions as the university expanded, enrollment increased, leaks happened, electricity was installed and the big challenge in 1895-a fire. Faulty wiring is believed to be the cause of the fire that destroyed the annex and Rotunda. McKim, Mead and White, a New York-based architectural firm, intended to restore Jefferson’s Rotunda, but the designers also elected to add modern touches as dictated by 1896 standards. The third floor was removed, the north terrace was added and fireproofing materials were incorporated. For instance, the firm commissioned Rafael Guastavino to create a clay tile dome to support the roof because these tiles were deemed to be more fire-resistant than concrete or steel.

In 1938 Alderman Library opened and the space in the Rotunda was reconfigured into offices. Marble was used to replace concrete balustrades on the terrace and the steps on the north and south sides of the building. As sometimes can happen with historical designs, people began to wonder what Jefferson would think about all these changes. So in the 1950s, a movement began to reinvent the Rotunda as Jefferson planned. Years of fundraising passed; the building was designated a National Historic Landmark in 1965; and architects at Ballou and Justice, Richmond, Va., began to prepare plans for a restoration. With work starting in the 1970s, the renovation involved interior redesign, reconstruction of Jefferson’s dome room and replacement of the dome’s skylight.

During this phase, a terne-coated metal roof was installed on the dome and painted white. The previous roof system was copper that had been allowed to patinate over the years, creating a green and white exterior. While copper wasn’t selected for the 1976 roof, the designers believed painting the terne-coated steel white created a similar aesthetic to the previous two roofs.

The Rotunda was untouched for many years before another renovation was considered for various reasons, including a rusting roof. “The painted terne-coated steel roofing that had been installed on the dome of the Rotunda in the 1970s had rusted through from the back side,” Palazzo says. “This deterioration was promoted by the formation of condensation on the back side of the metal roofing.”

 

The Renovation

In 2012 phase one of a two-phase renovation project began. The construction project was awarded to Christman-Gilbane, a joint venture construction management firm in Reston, Va. W.A. Lynch Roofing, Charlottesville, was awarded the roofing contract. It is believed that inadequate ventilation contributed to the formation of condensation on the underside of the metal roofing, resulting in the roof failure. While fireproof, the Guastavino tile dome and decking did not accommodate passive ventilation, which removes excess heat and water from beneath the roofing. A concealed venting system was installed at the intersections of the treads and risers at the seven steps in the roof, as well as at the top of the dome below the oculus.

“Heated air has low density so it will logically rise creating natural convection,” says Tom McGraw, executive vice president of W.A. Lynch Roofing. “This convection creates air movement below the roof and minimizes dead air spaces and the potential for condensation. The key to this is ensuring that you size the
‘intake’ venting similar to the ‘exhaust’ venting so that air will flow in an unrestricted fashion.”

It was determined the original tile deck could stay in place. After the previous painted metal panels were removed according to lead-abatement standards, a new wood deck was installed on furring over the tiles. This was covered with 30# roofing felt and red rosin building paper followed by the new copper roof.

Palazzo explains that when selecting the roofing material, several issues had to be addressed, including cost, durability and historic appearance. He says: “While three different types of metal roofing had been used historically, copper was chosen for its availability, constructability and performance characteristics. Copper was not the original roofing material, nor was it the most recently installed material. Often with historic roofing work some concessions have to be made to the competing needs of the building and contents; typically the exclusion of water is the highest priority.”

The 20-ounce Flat-Lock copper was supplied by N.B. Handy Co., Richmond. The roof required approximately 6 tons of copper, and W.A. Lynch Roofing sheared 4,000 individual tiles to approximate dimensions in its sheet metal shop. Exact dimensions had to wait until the material was in the field. McGraw says: “Because this building is almost 200 years old, you have to recognize that not everything is as true and square as one might hope. There are seven steps that circle the base of the dome, and each tread and riser changed in height and width all the way around the building.”

To ensure proper installation, W.A. Lynch Roofing set up a makeshift sheet metal shop on top of the scaffolding. Copper pieces were elevated to the rooftop and trimmed to the required dimensions. Each piece also had its edges tinned and folded before being installed.

The Lesson

The Rotunda is a piece of Americana that deserves a visit-in 2016. The day after graduation this May, the Rotunda closed for phase two of the construction project. At a price of $42.5 million, utility, fire protection and mechanical upgrades will be made, as well as a Dome Room ceiling replacement and construction of a new underground service vault. The roof also will be painted white, and leaking gutters will be repaired. Jeffersonian design again makes an appearance with the creation of marble capitals that will replace ones that are deteriorating.

Jefferson and multiple architectural firms, thousands of students, hundreds of faculty members, layers of renovation and a few disasters are all characters in the Rotunda’s story. With so much involved in a building that means a great deal to the university, it is clear why a basis of knowledge is always a good place to start when beginning a historical project.

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Kate Gawlik is a Lockport, Ill.-based writer who focuses on and design and construction practices.

Source URL: https://www.metalarchitecture.com/articles/cure-and-conservation/

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