The Rotunda at the University of Virginia, Charlottesville, was designed by Thomas Jefferson as the architectural and academic heart for what he termed the "academical village." Encompassing the rotunda, pavilions and student rooms along the lawn, the academical village was created on the assumptions that learning is a lifelong and shared process and interaction between scholars and students enlivens the pursuit of knowledge.
Jefferson modeled the rotunda after the Roman Pantheon, reducing the measurements so the rotunda would not dwarf the pavilions. In 1822, construction on the rotunda began and continued for four years. Jefferson died July 4, 1826, and did not live to see the rotunda's completion later that year. In 1976 during the 233rd anniversary of Jefferson's birth, The American Institute of Architects recognized the academical village as the most significant U.S. architectural achievement during the past 200 years. The rotunda also is listed as a National Historic Landmark and a United Nations Educational, Scientific and Cultural Organization World Heritage site.
The dome
The rotunda's dome is 67 feet wide and 18 feet tall and sits on a low-slope roof that extends 6 feet beyond the dome's bottom footprint. There are seven steps at the dome's base with the top tread being 10 feet above the deck. A 19-foot-wide oculus is at the top of the dome covered by a skylight. The dome originally was constructed of wood and burned in a fire in 1895. During reconstruction, Guastavino tile was chosen for its fireproof characteristics and a Guastavino tile vault, a patented system fabricated with thin terracotta tiles in three or four laminated layers set in cement, was installed. During the renovation, new steps were installed using pre-cast concrete treads on brick risers.
Installed in 1976, the rotunda's 8,000-square-foot terne-coated steel roof began showing signs of rusting during the 1990s. For the past 20 years, the university conducted a springtime ritual of sealing rusted holes with caulking followed by painting the entire dome roof to hide rust stains before graduation ceremonies.
The terne-coated steel was installed on rosin paper and asphaltic building paper over the cast-in-place concrete steps and Guastavino tile roof deck and over rigid insulation board on the upper dome. The absence of ventilation between the masonry substrate and steel's underside contributed greatly to the steel roof's deterioration. Because of ongoing damage, the university initiated a plan to replace the roof system ahead of other major building renovations.
An improved roof design
Taking into account the fabrication challenges associated with stepped domes, aesthetic requirements for a smooth surface similar to Jefferson's originally designed roof system and introduction of ventilation beneath roof membranes as good roofing practice, the project's architect, John G. Waite Associates, New York, designed a new 20-ounce copper roof system to be fabricated with custom-formed panels joined with soldered flat-lock seams. The copper panels would be installed on a vapor-permeable underlayment and attached to an elevated, spaced sheathing wood substrate to form a ventilation system between the masonry structure and new copper.
Work commences
Following a rigorous, thorough qualification and interview process, the University of Virginia's construction manager, a joint venture of The Christman Co., Lansing, Mich., and Gilbane Building Co., Providence, R.I., selected W.A. Lynch Roofing Co. Inc., Charlottesville, to install the rotunda's new roof system because of its extensive experience with steep-slope copper roof systems.
Tear-off work began in October 2012. Because the existing terne-coated metal roof system had multiple coats of lead-based paint that had been applied throughout the roof system's life, careful lead-based paint abatement and disposal were exercised to ensure the safety of workers, students and building occupants.
During tear-off, a temporary 0.60-mil-thick EPDM membrane was installed over the exposed tile deck. The EPDM membrane was custom-cut in-house and installed in 10-foot-wide trapezoidal pieces to keep the sizes manageable, and each piece was sealed to adjoining sections to fit the dome's geometry. The top of each section was attached to the dome's structure with an aluminum termination bar. This was done sequentially in three equal sections from the dome's bottom to the top so the EPDM membrane could be lifted and closed each day, allowing the masons and carpenters to complete substrate repairs and construction while keeping the building watertight.
"The entire building was covered independently four times, always leaving access in the areas where separate trades were working, yet always rendering a watertight seal at the end of each work day," says Tom McGraw, W.A. Lynch Roofing's executive vice president. "No leaks were experienced during the project thanks to a unique and innovative temporary roof design."
Learning curves
A large partial dome mock-up with steps was fabricated in W.A. Lynch Roofing's shop to refine copper roofing details, conduct water tests and evaluate paint systems. However, the rotunda's unusual shape coupled with inexact step dimensions created a daunting challenge for designing a flat-locked 20-ounce copper roof system.
To accomplish the desired symmetry on the steps, each of the seven risers required adjusted dimensions because of the reduced diameters of each ascending step. Developing these dimensions required the transition from the upper step to the dome's top to be carefully planned to ensure the symmetry continued from the bottom of the roof and over the dome, terminating at the oculus' base. All vertical riser pans had to align with the midpoint of the pan above it to achieve the correct visual offset. The connection of one step to the next required flat-locked horizontal pans on the tread, each with varied dimensions because of deviations in the widths of the actual treads.
"The problem with working on a domed building that is almost 200 years old relates to the lack of true dimensional symmetry," McGraw says. "You cannot mathematically determine sizing for the pieces of copper and make quantities of that size assuming they will correctly fit. The steps below the dome had varying heights in the risers and varying tread widths; these were not dramatic differences but enough of a variance that there was no duplication of individual copper pans."
To solve the dilemma, a small sheet metal shop was constructed on the scaffolding. Copper blanks of each particular size required for the treads, risers and dome were cut in W.A. Lynch Roofing's off-site sheet metal shop and shipped to the job site each day. Once the material was on the roof, specific dimensions were determined. Each blank then was cut to size, and the four sides were tinned and rotated in a heated solder trough. Then, each pan had the four sides folded on a roof-mounted brake in advance of the flat-locked installation and soldering.
It took several weeks to find a rhythm to the work flow, but once established, four independent crews were allowed to work on the dome's pie-shaped quadrants that were divided by expansion joints. At the height of work, there were as many as 17 crew members working on the rotunda project in addition to two workers responsible for opening and closing the EPDM membrane each day, two full-time off-site sheet metal workers and support personnel.
On top
As with the risers and treads, the dome was covered in flat-locked 20-ounce copper. Each piece was fabricated to ensure offsetting horizontal joints and vertical symmetry corresponded with the joint alignment of the risers and treads below. All joints were fully soldered.
At the oculus' perimeter, a radiused molding was fabricated by Heather and Little Ltd., Markham, Ontario, to replicate the original design. The previous molding installation was accomplished using multiple 12-inch pieces of terne-coated metal soldered together. Working with Heather and Little, a press was constructed to match the molding profile and oculus radius, allowing for longer lengths of copper to be used, resulting in a much smoother and monolithic finished product.
At the nosing of each step tread, a hidden, copper- and brass-fabricated vent screen was installed. A larger vent also was installed at the oculus' base to complete the passive ventilation path.
The 6-foot-wide low-slope roof at the steps' base is curved and has a built-in gutter along the outer edge for drainage. Because of the significant amount of foot traffic required to install the steps and dome, this roof area was the last to be completed. The area was protected throughout the project with adhered nail-base roof insulation and a reinforced EPDM roof system. As the EPDM membrane and insulation were removed, curved built-in gutters were installed and flat-locked copper was fabricated and installed to tie the gutters back to the first risers. At the same time, a low-profile custom-made Bilco® roof hatch was installed to allow for future roof access.
A demanding schedule
Although the contractual completion date was scheduled for Sept. 9, 2013, the university requested work to be sequenced and expedited to allow scaffolding removal before the university's final graduation exercises May 9, 2013. Because of delays with shop drawings and early construction activities, installation of the new copper roof system did not begin until January 2013.
A late start during winter also imposed a significant burden on production. Roofing workers encountered single-digit temperatures, high winds and unusual amounts of rain and snow during the project. Some inclement weather days were used for work required in the shop, but other days simply were lost.
To stay on schedule and meet the May 2013 deadline, W.A. Lynch Roofing implemented a work plan to complete the project in four months. Workers were committed to a seven-day, 10-hour-per-day schedule. As the schedule became tighter because of weather delays, W.A. Lynch Roofing enlisted support from Wagner Roofing Co., Hyattsville, Md., to assist with accelerating installation in advance of the looming completion date.
"Reducing a project of this magnitude from a nine-month schedule to essentially a four-month schedule is one of those requests you wish you'd never been asked," McGraw says. "It was incumbent on us to find a way to make it work. We extended our work schedule and called upon our friends at Wagner Roofing to assist with their highly skilled sheet metal workers to bolster the manpower on-site and help complete the project within the requested schedule."
Closing ceremony
With the help of Wagner Roofing and a dedicated team at W.A. Lynch Roofing, the rotunda reroofing project was completed April 22, 2013. Despite having its construction schedule reduced from nine months to four months and commencing work in winter, W.A. Lynch Roofing completed the rotunda's new copper roof system installation on time, on budget and without compromising quality. On May 19, 2013, the University of Virginia's graduation exercises were conducted without scaffolding encasing the rotunda and with a beautiful copper dome proudly overseeing the ceremonies.
More than 6 tons of 36- by 120-inch flat copper sheets and 4,000 individual pieces of 20-ounce copper were used to reroof the rotunda.
"The most rewarding aspect was being part of an incredible team of professionals," McGraw says. "To do such a high-profile and extremely difficult project in such a short period of time was incredible and happened thanks to the assembled team of sheet metal mechanics, owner representatives, architects and construction managers. I can honestly say that after 40-plus years in the business, this is my legacy project and I am humbled to have been a part of it."
For its exceptional workmanship, W.A. Lynch Roofing received two NRCA Gold Circle Awards in the Innovative Solutions—Reroofing and Outstanding Workmanship—Steep-slope categories.
Chrystine Elle Hanus is Professional Roofing's associate editor and NRCA's director of communications.
Project name: University of Virginia's Rotunda
Project location: Charlottesville, Va.
Project duration: October 2012-April 2013
Roof system type: Copper
Roofing contractors: W.A. Lynch Roofing Co. Inc., Charlottesville, Va.; Wagner
Roofing Co., Hyattsville, Md.
Product manufacturers: Bilco, New Haven, Conn.; N.B. Handy Co., Richmond,
Va.
Gold Circle Awards categories: Innovative Solutions: Reroofing; Outstanding
Workmanship: Steep-slope
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