The sound of roofing

Mahan Slate Roofing restores Groton School's bell tower


The ambition and values that drove a young Episcopal priest to found Groton School, Groton, Mass., in 1884 still influence the school more than 130 years later. Built on 415 acres of farmland along the Nashua River, the school initially accepted 24 students, and by 1920, it grew to admit 180 students. More than 380 students currently are enrolled in the school.

Recently, one of Groton School's iconic 19th century buildings was renovated for the 21st century. The school's expanded "Schoolhouse" integrates the original structure's majestic windows with a new light-filled, 50-foot-tall forum, which leads to a new science, technology, engineering and mathematics addition.

Energy efficiency was a primary project goal. Despite its increased size, heating and cooling the renovated Schoolhouse will cost about the same thanks to newly installed geothermal wells, light and movement sensors, skylights with energy-efficient glass, and other energy-saving measures.

In 2011, Groton School began a roof remediation program. During the past six years, Mahan Slate Roofing Co. Inc., Agawam, Mass., has replaced more than 1,200 squares of slate and copper roof systems on the school's campus, including St. John's Chapel, which consisted of more than 80 squares of copper roofing. During 2014-15, Mahan Slate Roofing completed restoration of the school's bell tower.

Scope of work

There was an extensive amount of work done during the seven-month project, including staging the entire bell tower; a complete replication of the copper weathervane; installing 60 squares of slate, flat-seam copper, mahogany wood trim and custom heavy-duty copper gutters; and restoring the clockworks and bell while ensuring the work was completed with the approval of the school's historian.

One of the first major hurdles was properly erecting scaffolding, which required an engineer's approval because of the complex design and anticipated wind loads on the scrim.

A scrim was needed because most of the copper work was painted white after it was restored to keep it historically accurate, so the area inside the scrim was heated to allow the paint to cure properly. This also helped keep the cold and wind out while Mahan Slate Roofing's crew worked during New England snowstorms.

The scaffolding was fully wrapped to provide debris containment and a climate-controlled atmosphere for workers during the restoration process.

In the details

Mahan Slate Roofing workers manually removed 60 squares of slate from the school's main roof and replaced them with 18- by 10-inch Vermont unfading green slate.

The architectural copper dome was deconstructed carefully to save pieces for duplication and transported to Mahan Slate Roofing's sheet metal shop where the pieces were replicated by Mahan Slate Roofing craftsmen. Once completed, the copper was returned to the job site and installed on the tower.

The project specified replacing the flat-seam copper bell tower floor and flat-seam copper radiused dormers. Because of years of water infiltration, remediation of extensive structural deterioration of the belfry dome supports and bell carriage was required. The custom-fabricated copper dome was gilded with 14-karat gold to create a striking campus focal point.

About 45 squares of additional 20-ounce copper were used when workers re-clad the dome. Completing these tasks during limited daylight posed a challenge.

"During winter when the days were short, lighting was an issue for our workers," says John Mahan, vice president of Mahan Slate Roofing. "String lights were installed on every level to provide additional lighting, but fitting and soldering the custom-fabricated copper was difficult."

In addition, PVC and fiberglass were installed on the railings and balusters at the school's Ringing Chamber level; epoxy resin reproductions were created of the decorative oak leaf clusters and the "egg and dart" clock bezel; fiberglass castings of the finials, column capitols and bases were built; and siding and cornice decorative millwork was fabricated from South American mahogany.

The bells and whistles

The school's bell originally was fabricated in 1889 by Meneely Bell Co., Troy, N.Y., and was restored by Meeks, Watson and Co., Georgetown, Ohio.

One major change the school's historian requested was moving the lights that illuminate the bell tower because they were not historically accurate and were considered aesthetically unpleasant. Mahan Slate Roofing workers built recessed copper troughs into the slate and copper roof systems so the lights would be hidden from view but still adequately light the new bell tower.

The clockworks were built in 1898 by E. Howard Co., Boston, and restored by Freeport, Maine-based Balzer Family Clockworks, a national clock restoration specialist. A new automatic winding clock system was included in the restoration process that came out so well the building owner requested the clockworks be relocated 30 feet below the original position in the back of the clock's face where they can be seen in a custom-designed viewing case in a hallway of the classroom building. This added another layer of complexity, including fabricating special linkage and custom lighting in the display case.

Ringing in a new era

In January 2015, Mahan Slate Roofing completed its work on Groton School's bell tower on time and on budget, helping create one of the most beautiful, functional and energy-efficient academic buildings in the U.S.

"From the time Mahan Slate Roofing signed the contract until the time the last truck pulled away from the completed project, Mahan Slate Roofing was dependable, cooperative and safe," says Robert Fulmer, design consultant and project manager for Groton School.

For attention to historical details and excelling in craftsmanship, Mahan Slate Roofing received a 2017 Gold Circle Award in the Outstanding Workmanship: Steep-slope category.

"It was rewarding to see the final product come together after the scaffolding was removed," Mahan says. "Many people worked together to properly restore a building more than 130 years old and keep it historically accurate."

Chrystine Elle Hanus is Professional Roofing's associate editor.



Project name: Groton School Bell Tower
Project location: Groton, Mass.
Project duration: June 2014-January 2015
Roof system types: Copper; slate
Roofing contractor: Mahan Slate Roofing Co. Inc., Agawam, Mass.
Roofing manufacturers: New England Slate Co., Poultney, Vt.; Revere Copper Products Inc., Rome, N.Y.; Vermont Structural Slate Co. Inc., Fair Haven, Vt.
Gold Circle Awards category: Outstanding Workmanship: Steep-slope

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