The Martin County courthouse, Fairmont, Minn., was constructed in 1907 in the Beaux Arts style. The first story is clad in Michigan sandstone while Bedford limestone wraps the two top stories. But it is the copper dome capping the building that draws the eye. Four, 7-foottall clocks sit at the base of the dome, and copper eagles with wings spread perch between each clock. The building was added to the National Register of Historic Places in 1977.
Duplicating old-world craftsmanship with modern techniques and understanding brought this copper dome into the new millennium
But hard times hit the 50-foot dome and it began to leak. Renaissance Roofing, Belvidere, Ill., was awarded the contract to replace the copper cladding. It is the kind of work at which the company excels. In fact, in the 2021 MCN Project Excellence Awards, Renaissance won the craftsmanship category for its work on the Mississippi County Courthouse dome replacement in Osceola, Miss., and now the company takes the 2022 award in the same category for another dome in another county.
Judge Ron van der Veen, FAIA, LEED AP. said, “This project is exquisite. Craftsmanship wise, it’s hard to beat this. This is meticulously crafted.”
The original dome showed true craftsmanship as well, especially the copper cladding, but at some point, no one knows when, a concrete deck that served as the substrate for the dome was removed, likely due to deterioration. With the dome suspended it began to leak and show other signs of failure.
“The goal for us is to reproduce the appearance while trying to improve the watertightness or the longevity of the system,” says Bob Raleigh, III, president, Renaissance Roofing. “So, there are areas or components that are improved upon because the initial installation.”
That process began by redoing the steel structure on which the dorm sat. Renaissance added additional purlins and installed a substrate of clear 1-foot by 8-foot pine. With that foundation, the company was able to bring its expertise to the copper cladding. “With the ability of hindsight,” says Raleigh, “we can see what didn’t work as intended. That’s an advantage we have.”
Lon Gorsch was the project supervisor for Renaissance and also handles estimating and bidding, so he was involved in the project from the very beginning. He explains, “Allowing the copper to move is key. The old system was 100% soldered and cracked open over time. So, where there is a continuous ring, we will have a clevis seem in a couple of places. Basically, that allows that to expand and contract so the copper doesn’t break, or the metal doesn’t get weak.”
Not only were the techniques updated, but the materials were as well. In addition to the improved steel structure, Renaissance replaced the original 16-ounce copper with 20-ounce copper.
To duplicate the existing dome, workers removed pieces of the copper that were then duplicated in the shop. “It’s a true dome,” says Gorsch, “so it’s curved in both directions. When that happens, everything is a compound curved and sheet metal wants to stay flat. Extra effort and extra skill are involved in making every piece.”
That kind of effort doesn’t come quickly. Scaffolding for the dome was installed in July 2020 and removed in September 2021. “In round numbers,” says Raleigh, “the fabrication of the copper components in our studio represented 20% of the total labor required. The carpentry and steel modifications represented 20% and the field installation of the copper was 60%.”
The four eagles were a special casting. Two of them survived, so Renaissance was able to make molds from those and created four new eagles. Those architectural elements were the kind of thing that could be ordered out of a catalogue and there are still specialty shops that duplicate them. Renaissance did it in house. “We took them apart and copied each section almost the same as it was originally stamped out,” says Gorsch. “There were probably 50 parts that were pressed out and soldered together.” Inside the eagles there is a copper armature to support the wings and body, and a pipe goes through the feet to attach to the dome. The value of those four eagles was equal to about 10% of the project.
Those were all challenging, but Gorsch says the biggest surprise was the clock faces. “Getting the trim and new clock faces in a flat plane, plumb and level was difficult,” he says. “The steel framing looked pretty good, but it was irregular and there was no deck to work from.” Renaissance had to create a new deck and put everything together in the sheet metal shop in a different way than previously. “Getting all that built out, so everything fit and looked as good as possible was a real challenge.”
There are more than 3,000 counties in the United States. Not all of them have copper domes and not all of them need repairing, but there may be many more that do. If so, it should be noted that Renaissance Roofing has shown a level of expertise and craftsmanship for this kind of work that caught the judges’ eyes two years in a row.
