Putting a new roof on the historic Tryon Palace, the first permanent capitol of the Colony of North Carolina and home of the royal governor and his family, presented a number of challenges. First and foremost was the need to protect the historic structure and its furnishings.
"The original building was constructed during the 1770s and consisted of a perimeter gutter, a mansard tiled roof and a flat roof on top," said John Willers, president of Rooftop Systems Engineers, PC, which specified the roofing system for the New Bern, N.C., landmark building. "We could not afford to have a leak during tear-off and installation, and we needed a system that could handle a lot of foot traffic."
Willers recommended installing a Johns Manville DynaLastic® SBS modified bitumen base sheet as a temporary roof so Curtis Construction, the roofing contractor, would not have to worry about water getting into the building while its crew installed the permanent roof. For the permanent roof, Willers selected a JM cold-applied SBS modified bitumen roofing system for the flat portion and gutter because it provided the redundancy of a built-up roof, but was easier to use in the confined space along the roof’s perimeter where the use of hot asphalt would be prohibitive.
"There were a lot of unique details, particularly in the canyon-like perimeter gutter," Willers said. "The gutter is 2 1/2 feet wide with a parapet on one side and a mansard roof on the other. To protect this area, we installed an additional ply of DynaLastic 180. We clad the back of the parapet wall with modified asphalt material."
On the flat roof, Curtis Construction installed two layers of 1.6-inch ENRGY 3® polyisocyanurate insulation with a 1/2-inch Fesco® Board overlay. One layer of DynaLastic 180 felt was cold applied over the cover board, followed by a torch-applied DynaWeld™ Cap FR Sheet. The intersection of the flat roof and the tile roof required some special detailing, as did the flashings around a new skylight.
"With visitors coming every day during the project, cold applied modified bitumen was the best choice," said Billy York, project manager for Curtis Construction. "We secured an area at the back of the building to stage the materials, which we brought to the roof using a hydraulic ladder hoist."
Philippe Lafargue, Tryon Palace’s deputy director, was pleased the roofing crew worked closely with him to avoid disruption to guests.
"During the project, the North Carolina Symphony performed at the Palace for 2,500 people," Lafargue said. "The crew cleaned up the work area and covered the materials with a tarp prior to the performance. I am very pleased with the entire team and the completed roof."
Rooftop Systems Engineers of Raleigh, N.C., has been in business for 11 years. Curtis Construction of Kinston, N.C., has been roofing industrial, commercial and institutional buildings for 20 years.
For more information about Johns Manville, visit www.jm.com.