Article

Peddocks Island: Repointing at Fort Andrews

Four crew members wearing hard hats in front of an old brick wall. Three of them are on scaffolding, and one is standing on the ground below. The mortar in several parts of the wall is much brighter white than the mortar on the rest of the wall.
Crew members repointing an exterior wall of the Fort Andrews gymnasium. May 2024.

Student Conservation Association photo, L. Prelgovisk.

A group of corps members sitting on the ground, looking at a man sitting on the ground to the right. He is talking while looking down at an angle grinder in his hands, and there are several other tools on the ground in front of him.
While on Peddocks Island, the Historic Preservation Corps were trained in historic preservation skills. Here crew members are being instructed on different masonry tools and how to use them. May 2024

Student Conservation Association photo, L. Prelgovisk

The Student Conservation Corps Massachusetts Historic Preservation Corps (SCA HPC) trains the next generation of preservationists while also giving them the opportunity to serve their community. One example of this is the Peddocks Island repointing project at Fort Andrews, where corps members were trained on how to restore historic brick while preserving this Boston Harbor Island's history.

Site History

While Peddocks Island has a long history, the history of Fort Andrews dates back to the late 1800s. Around this time, Peddocks caught the US Military's eye as a potential site for a fort to increase Boston Harbor's defense. This lead to the construction of Fort Andrews, beginning in 1898. By the start of World War I (WWI), the Fort's defenses were already out of date, so it was primarily used as a training facility once the US entered the war.[1]

A black and white aerial photo of part of an island. The visible part of the island is circular and lined with a sandy beach, and is connected off-image to the rest of the island by a thin strip of land going into the top right corner of the image.
Aerial map of Fort Andrews circa 1944.

Boston Public Library

Following WWI, the Fort saw little use, and in 1928 was put under caretaker status, where only a few officers are stationed as security. Once World War II started, Fort Andrews was again used primarily for administrative use rather than defense.[2] During the war, the island was also home to the Italian Service Units, a group of former Italian prisoners of war who were brought to do work in the Boston area following Italy’s surrender.[3]

Fort Andrews was put under caretaker status again in 1947.[4] In 1970, Peddocks Island was purchased by the Metropolitan District Commission, which would later become the Department of Conservation and Recreation (DCR) and made part of the Boston Harbor Islands State Park. During this time, the number of permanent residents decreased, many selling their homes to the state. Peddocks was made part of the Boston Harbor Islands National and State Park in 1996 and is today managed by both DCR and National Parks of Boston.[5]

A corner where two old brick walls meet. Much of the mortar has crumbled, leaving empty spaces between the bricks. A corner where two old brick walls meet. Much of the mortar has crumbled, leaving empty spaces between the bricks.

Left image
A section of wall on the Fort Andrews gymnasium BEFORE repointing.
Credit: Student Conservation Association photo, R. Davis

Right image
A section of wall on the Fort Andrews gymnasium AFTER repointing.
Credit: Student Conservation Association photo, R. Davis

Project Overview

This project taught new crew members about masonry repointing. Over time, the mortar on brick structures start to deteriorate, cracking and eventually falling out of the wall. This disintegration of the mortar allows water to seep further into the wall, eventually causing severe damage to the bricks. Repointing is a process during which preservationists remove old, damaged mortar and replace it with new mortar.

Project leads first briefed the crew members on the basics of masonry, as well as the tools and the materials used for repointing. Crew members were then sent to identify failing mortar on the walls of the gymnasium and bakery buildings of Fort Andrews and began using chisels and angle grinders to remove it. Next, they were given a demonstration on how to mix mortar and how to apply it to a structure. In addition to gaining hands-on repointing experience, the crew members also learned other important skills, including scaffolding setup and applying an acid wash.

This training exercise, alongside training the next generation of preservationists, provided vital repairs and service to the National Parks of Boston and Department of Conservation and Recreation.

Preservation Efforts

SCA HPC Crew members conducted the following steps in the repointing process at Fort Andrews on Peddocks Island.

Repointing begins with using masonry chisels or an angle grinder to clear out the mortar. Masonry chisels and a hammer are used for spots where the mortar is crumbling heavily and require less effort to clear. For areas where the mortar is more intact or otherwise tough to remove with a chisel, an angle grinder can be used to clear out the mortar, as long as it is used safely.

A crew member wearing a hard hat, N95 mask, safety glasses, and earplugs holds an angle grinder up to an old brick wall, removing some of the mortar.
An angle grinder is used on mortar that is not able to be removed with just a chisel and hammer. May 2024.

Student Conservation Association photo, A. Perault

Scaffolding set up at the corner of an old brick building. There are four crew members wearing hard hats and holding hammers and chisels, two of them on the ground level and two of them sitting on the scaffolding platform above.
Historic Preservation Corps members not only learned how to repoint, but other skills such as how to set up and take down scaffolding.

Student Conservation Association photo, L. Prelgovisk

The next step is to make new mortar and apply it to the structure. When mixing mortar, it is important to be careful of how the mixture is composed, particularly how hard the material will be when it finishes drying. If the mortar is harder than the bricks surrounding it, water will seep into the bricks instead of the mortar, damaging them over time. Brick is much more difficult to replace than mortar, so the mortar is designed to be softer than the brick so that it gets damaged first.

When working on a historic building, like those at Fort Andrews, it is especially important to identify the correct composition of the mortar as historic brick is frequently much softer than modern-day bricks.

A Historic Preservation corps member wearing a hard hat applying mortar to a brick wall.
A crew member applies mortar to a brick wall at Fort Andrews.

Student Conservation Association photo, L. Prelgovisk.

After the proper ratio of ingredients is determined—in the case of the Fort Andrews buildings, a mix of Portland cement, lime, sand, and water—the ingredients are mixed up and applied between the bricks. This is done by using a small pile of mortar on a trowel or masonry hawk—a small sheet of metal with a handle—to hold it up to the wall and push it in between the bricks using a masonry jointer, a thin, trowel-like tool that can fit in the space between bricks.

After the mortar is applied, water is regularly sprayed on it to keep it from drying too fast, which could lead to it crumbling out. Finally, once the mortar is mostly dried, a wash is applied with muriatic acid—while wearing proper safety equipment, such as gloves and safety goggles—to remove any mortar stuck to the faces of the bricks.

Contributed by: Greg Bsales, SCA Historic Preservation Corps Crew Member

Footnotes

[1] Cultural Landscapes Inventory: Peddocks Island, Boston Harbor Islands National Recreation Area (Boston, MA: National Parks of Boston, National Park Service, US Department of the Interior, 2021), 33-38. NPS History.

[2] Cultural Landscapes Inventory, 38-39. NPS History.

[3] "Italian Service Unit of Boston: World War II," Boston Harbor Islands National & State Park, National Park Service.

[4] Cultural Landscapes Inventory, 40. NPS History.

[5] Cultural Landscapes Inventory, 56-58. NPS History.

Tags

Boston Harbor Islands National Recreation Area

Last updated: September 6, 2024