Repointing Fort Andrews: Training Preservationists on Peddocks Island in Boston Harbor

The Student Conservation Association's Massachusetts Historic Preservation Corps trains the next generation of preservationists while they serve their community. On Peddocks Island in Boston Harbor, a crew learned to restore historic brickwork at Fort Andrews — repointing the walls of the fort's gymnasium and bakery in May 2024.

Fort Andrews

• Late 1800s: the U.S. military eyed Peddocks Island as a site to strengthen Boston Harbor's defenses; construction of Fort Andrews began in 1898.
• World War I: its defenses were already outdated, so it served mainly for training.
• 1928: placed under caretaker status, with only a few officers stationed for security.
• World War II: used mainly for administration. The island also housed the Italian Service Units — former Italian prisoners of war brought to work in the Boston area after Italy's surrender.
• 1947: back to caretaker status.
• 1970: bought by the Metropolitan District Commission (later the Department of Conservation and Recreation) for the Boston Harbor Islands State Park; many remaining residents sold their homes to the state.
• 1996: made part of the Boston Harbor Islands National and State Park, now managed jointly by the Department of Conservation and Recreation and National Parks of Boston.

Why repoint

Over time the mortar in brick walls deteriorates, cracks and falls out, letting water seep deeper and eventually badly damaging the bricks. Repointing means removing the old, damaged mortar and replacing it.

The training

Project leads first taught the crew the basics of masonry — its tools and materials. The crew then found failing mortar on the gymnasium and bakery, cleared it out, and learned to mix and apply new mortar. They also learned to put up and take down scaffolding and to apply an acid wash. The work gave vital repairs to National Parks of Boston and the Department of Conservation and Recreation.

How it's done

1. Clear out the old mortar. Use masonry chisels and a hammer where it is crumbling, and an angle grinder — carefully — where it is still hard.
2. Mix mortar softer than the brick. If mortar is harder than the bricks, water goes into the bricks instead and damages them; since brick is far harder to replace than mortar, mortar is made to fail first. Getting the mix right matters most on historic buildings, whose bricks are often much softer than modern ones. At Fort Andrews the mix was Portland cement, lime, sand and water.
3. Pack it in. Hold a small pile of mortar up to the wall on a trowel or masonry hawk (a small metal sheet with a handle) and push it between the bricks with a masonry jointer, a thin, trowel-like tool.
4. Keep it damp. Spray the new mortar with water regularly so it doesn't dry too fast and crumble.
5. Clean the faces. Once the mortar is mostly dry, wash the bricks with muriatic acid — wearing gloves and goggles — to remove mortar left on their faces.

Sources

Based on "Peddocks Island: Repointing at Fort Andrews," contributed by Greg Bsales, SCA Historic Preservation Corps crew member, Boston Harbor Islands National Recreation Area, National Park Service, citing the Cultural Landscapes Inventory: Peddocks Island (National Parks of Boston, 2021); rewritten in hubnx's own words. The source calls the program the "Student Conservation Corps" once; its photo credits give the Student Conservation Association. Its photographs, credited to the Student Conservation Association, and a 1944 aerial view from the Boston Public Library are not reproduced.