Cataloging, replacing, and replicating cracked stones was just one of the tedious construction feats achieved in the $4.3 million restoration of two 120-foot bell towers flanking Bowdoin College Chapel, in Brunswick, Maine, originally erected by members of the state's Ancient Order of Masons from 1845 to 1855.
It all started in 1995, when E/A firm Simpson Gumpertz & Heger (SGH), Waltham, Mass., was commissioned to replace the chapel's roof. At the time, severe cracks and bulges were discovered in the tower walls. Upon investigation, SGH found water penetrating through the windows and floors and washing away the masonry. Structural analysis revealed that the weight of the towers' spires was creating vertical cracks.
SGH submitted a scope of work narrative to the college, which sent it to outside professionals for review. The peer reviewers concurred wholeheartedly with SGH's plan to remove the deteriorated masonry and design a new precast concrete belfry and spire.
Before reconstruction could begin, the team cataloged the exact number, location, and size of more than 4,500 stones. After building mock-up panels and studying the material's performance, they decided to use mortar and grout containing portland cement.
Demolition began in the spring of 2003. A temporary roof
Bowdoin College's 120-foot bell towers were completely restored. Peer reviewers approved the plan to use precast units.Photos: Simpson Gumpertz & Heger
and tarps were erected to protect the tower core as each damaged stone was carefully removed and either thrown out or marked for reuse as a smaller replacement stone. In all, 747 veneer stones in the two towers were replaced, using rock extracted from an abandoned quarry.
The team used epoxy pinning to preserve reused decorative stones. They were able to replicate the ashlar pattern of the façade by fabricating replacement stones that precisely matched the dimensions of the fractured stones.
The original pebbled glass in the south tower had been shattered by a lightning strike in 1894 and replaced with plain glass. Luckily, the team was able to obtain virtually the same pebbled glass from a fabricator in Indiana.
Bowdoin College's 120-foot bell towers were completely restored. Peer reviewers approved the plan to use precast units. Photos: Simpson Gumpertz & Heger
They also installed a new concrete belfry floor and replaced the masonry window arches with reinforcing steel and cast-in-place concrete. Thirteen existing bells were reinstalled, along with two new ones that were added to expand the bell tower's repertoire, in time for the chapel's re-dedication last October.