Smithsonian Institution Building “The Castle”

Smithsonian Institution Building – “The Castle”

Location Washington, DC

Category Cultural

Water Infiltration Investigation, Thermal Moisture Survey, and Third-Party Building Envelope Inspection Services

Designated as a National Historic Landmark, the Smithsonian Institution was established in 1846. The Smithsonian Institution Building, more commonly known as “The Castle,” was designed by James Renwick, Jr. in a Romanesque Revival style and constructed from 1847 to 1855. The exterior of the facade is composed of red sandstone, which was quarried in Montgomery County, Maryland. Until 1881, The Castle housed the Smithsonian Institution’s operations, including research, administration, lecture and exhibit halls, libraries, laboratories, storage, and living quarters for the Secretary of the Smithsonian. Today, the Castle houses administrative offices and the main Smithsonian Visitor Center.

Hoffmann Architects + Engineers addressed building envelope issues with the Castle’s flag tower and stone masonry facade.

Flag Tower Water Infiltration Mitigation

The area in and around the third floor of the flag tower was known to have moisture infiltration; however, the causes and remedies were unknown. Hoffmann conducted a water infiltration investigation, which included a thermal moisture survey of the interior of the flag tower. The design team determined that the primary source of water to the interior was through defects in the exterior building envelope. Deteriorated mortar joints and stone along the entire height of the tower resulted in multiple areas with peeled paint, window deterioration, and mold growth. In addition, frozen pipes had burst, causing damage to the interior spaces. Hoffmann provided a report detailing problematic conditions and repair recommendations to address the water infiltration and remediate the damage.

Stone Masonry Facade Restoration

Since the Castle is designated as a National Historic Landmark, special attention to the quality of the workmanship and materials selected for installation was required to satisfactorily preserve and restore the historic elements and finishes. Hoffmann conducted an assessment of the existing mortar, displaced stones, sealant joints, stone surfaces, roof scuppers, and downspouts. During the repair phase, our design professionals observed construction and prepared detailed field observation reports, verifying that the work was performed in compliance with the contract documents and the Secretary of the Interior’s Standards for the Treatment of Historic Properties.

As the signature building representing the world’s largest museum complex, the Castle is the centerpiece of the institution and the gateway to its collections and research centers. By resolving underlying conditions, Hoffmann’s design team helped the Smithsonian mitigate the detrimental effects of weather, age, and wear, preserving this landmark for millions of future visitors.