Built between 1901-03, Cascade County Courthouse in Great Falls, Mont., is a three-story English Renaissance Revival-designed structure constructed from gray sandstone quarried from hills 6 miles west of the Missouri River. The building's four exterior columns are made of Tennessee marble; the 35-foot-wide dome is copper and supports a 15-foot-tall Statue of Justice; and the halls and wainscoting are laid in mosaic tiles.
On July 4, 1903, contractors completed work on the building. During World War II, after the attack on Pearl Harbor, the courthouse's dome was used to watch for enemy aircraft. In 1980, the courthouse was placed on the National Register of Historic Places and has been included in the Great Falls Northside Residential Historic District since 1991.
Throughout the years, much of the building's interior has been altered to meet changing needs; a majority of the original furnishings have been removed and sold. During 2016-18, Renaissance Roofing Inc., Belvidere, Ill., restored Cascade County Courthouse's copper roof system and dome employing current design methods and standards.
Renaissance Roofing began work on the courthouse in June 2016.
"We erected scaffolding with rails and debris netting around the entire building perimeter to the height of the gutter line," says Lon Gorsch, project manager for Renaissance Roofing. "This allowed us to work safely anywhere on the roof. It also made it easy to safely access the work at the entablature and balustrade at the perimeter of the roof that also was being replaced in its entirety."
The original 10,700-square-foot main roof area consisted of rare 20-ounce batten-seam copper over asphalt felt and rosin paper on a 2-inch tongue-and-groove wood deck supported by the building's superstructure.
To keep the building watertight, workers carefully removed the batten-seam copper and existing underlayment in sections.
"We started in the pocket areas and the areas below the water diverters that directed water into the existing roof drains," Gorsch explains. "These areas needed to be completed early in the process to be sure we could maintain a watertight condition throughout the winter season."
Next, workers applied self-adhering Grace Ultra® underlayment over the existing wood deck. To protect the new underlayment from extended sun exposure, workers used synthetic felt when necessary.
Meanwhile, in Renaissance Roofing's Illinois shop, craftsmen were custom-fabricating more than 1,800 copper panels. Using a roll-forming machine with 20-ounce Revere Copper Products coil stock, workers fabricated 42-foot-long panels with an installed 36-inch exposure. This required locking strips to be soldered to each panel to allow securement of succeeding panels.
The fabricated panels then were crated for shipment to the job site 1,300 miles away. Once on-site, workers installed the copper batten-seam panels using traditional folding methods adopted by the Copper Development Association and manufacturer Revere Copper Products.
Below the batten-seam copper are pitch pockets and a 2,500-square-foot gutter system that incorporated an innovative design using fully soldered flat-seam 20-ounce copper roof panels and built-in copper water diverters to direct water to the internal drain system.
"This was a unique system that was difficult to detail," Gorsch says. "The layout of the batten-seam roof determined the high points of the diverters. We had to determine these locations before installing the flat-seam areas and diverters below."
In addition, the entire main roof perimeter consists of an entablature detailed with a copper balustrade system composed of more than 140 spun-copper balusters in 12 rail sections.
"A traditional batten-seam roof system is relatively rare; we don't see those too often," Gorsch says. "The entablature and balustrade system around the roof perimeter are unique, as well. Many times, when you see a system like that, it has a parapet wall with a low-slope roof behind it."
Using stainless-steel armatures, workers rebuilt each rail section to be self-supporting and assembled them in the Illinois facility before transporting them to Great Falls for installation with the aid of a 275-ton crane. Each rail post was reworked using wood, underlayment, and customized copper panels and caps, requiring flashing to be incorporated into the stone and cast-iron components that also were restored.
"Renaissance Roofing brought experience, expertise and craftsmanship to this project," says Paul Filicetti, AIA, associate historic architect for A&E Architects, Missoula, Mont., the project's consulting architect. "Their crews did an outstanding job at problem-solving difficult conditions for numerous copper roof details."
For the tower dome, workers applied self-adhering Grace Ultra underlayment and rosin paper to the wood deck followed by 20-ounce flat-locked copper panels custom-fabricated by Renaissance Roofing workers who used the original panels as templates.
The drum beneath the dome was re-clad in 20-ounce copper that required extensive custom-tooling by Renaissance Roofing workers to fabricate the intricate, curved ogee patterns within the wall and ceiling panel systems.
The tower's pedestal also was re-clad in 20-ounce copper panels. For the pedestal's balcony roof areas, workers fully soldered 20-ounce flat-seam copper panels that also required flashings to be incorporated into the stone and cast-iron components.
In addition, workers restored the cast iron around the tower's drum, replaced curved windows and sashes, and painted these components.
An iconic courthouse
After nearly two years, 17,000 man-hours and 55,000 pounds of copper, on May 15, 2018, the $4.3 million roof system renovation project on Cascade County Courthouse was completed.
During Renaissance Roofing's work on the courthouse, more than 88 inches of snow were recorded during the 2017-18 season, the second-most snow recorded for the Great Falls area. Although winter weather and unforeseen carpentry issues, such as rebuilding the entablature substrate, caused some delays, the Renaissance Roofing team persevered and successfully completed its work on the one-of-a-kind, historical building.
"Renaissance Roofing spent countless man-hours understanding historical conditions and developing field and shop mockups to ensure the new copper roof system met the intent of the drawings, maintained historical building and roof system conditions, and met modern installation standards," Filicetti says. "The new copper roof system upholds one of Montana's iconic courthouses and re-established its character-defining feature—the dome."
Project name: Cascade County Courthouse
Project location: Great Falls, Mont.
Project duration: June 2016-May 2018
Roof system types: Copper
Roofing contractor: Renaissance Roofing Inc., Belvidere, Ill.
Roofing manufacturers: GCP Applied Technologies Inc., Cambridge, Mass.; Revere Copper Products, Rome, N.Y.