The Copper and Slate Puzzle

By the late 19th century, moisture and termites had damaged a number of framing elements at the first-floor level of the Mansion. Mount Vernon staff undertook localized repairs involving replacing wooden framing elements with brick and slate added to the top of the foundations. Sheet copper was inserted between the brick and slate and the remaining wood framing to act as shields preventing termites from reaching the wood.

Such repairs resolved the immediate problems but inadvertently impacted the integrity of the original structural system.

So, the copper and slate fragments discovered by the Archaeology team are part of a larger Mount Vernon story—a story that continues to unfold at this very moment. 

During the Mansion Revitalization Project, Preservation carpenters are addressing areas of the framing that were impacted by the installation of termite shields. They will replace non-original floor joists and sills and reconstitute the joinery between elements, enabling the structure to again function as intended by 18th-century carpenters.