Restorer’s art gets high-tech boost

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he historic Georgetown mansion at Tudor Place looks like a skinned cat these days.

The exterior of the spacious 19th-century structure at 1644 31st St. NW, former home of Martha Washington’s descendants, has been shorn temporarily of its damaged stucco as part of an ongoing restoration project with a high-tech slant. What remains is the underlying red brick facade, which hasn’t been seen since 1914.

The plan is to repoint the bricks, replace the stucco by mid-October and continue taking other extensive corrective measures to upgrade the handsome 1816 house, a National Historic Landmark.

The house, designed by William Thornton, the man credited with designing the U.S. Capitol with the approval of President Washington, is “connected to all the big names in American history,” says Jana Shafagoj, director of architectural and landscape conservation at the site.

Until the project began, she says, “nobody has understood how the house was put together.” Upon completion, Tudor House again will be covered with a beautiful gold-toned stucco, and the archives will be full to bursting with images and artifacts to be pored over by historians and architects for years to come.

Functionally a museum open to the public and operated by the Tudor Place Foundation, the house is said to contain the most important trove of George Washington artifacts outside of Mount Vernon. However, the residence, praised by architects as the District’s most historically intact of its kind, is also achieving prominence for another, very different reason. It is the first small house to have a special advanced laser scanning technique used to map its restoration in detail.

The 3-D photogrammetry technology, a high-definition documentation method known as HDD, can chart with microscopic precision the exterior and interior of any structure or site undergoing study or repair. Resulting images are valuable for learning more about a structure than otherwise could be seen by the naked eye and thus making sure conservation and renovation efforts are as successful as possible.

By “reading” the exposed brick masonry of the house with the help of a laser “eye,” Tudor’s professional staff also can learn much more about how the house evolved through nearly 200 years of its history. Clues are as small as nail types and brick shapes.

The method is credited to the nonprofit San Francisco-based Kacyra Family Foundation, which in 2002 established a nonprofit high-tech project known as CyArk to aid in preserving and protecting world-famous cultural-heritage sites. HDD has been used on such places as ancient Thebes, Pompeii, Tikal in Guatemala and Angkor in Cambodia. The Statue of Liberty is undergoing a similar review.

CyArk’s goal is to produce the most accurate 3-D models possible of World Heritage Sites and have them available in a public archive (http://archive.cyark.org).

The process looks simple enough to an outsider, but the actual operation involved is digital photography raised to a higher level. A tall, cameralike device contains a slow-moving metal arc that rotates 360 degrees. It rests atop a stand positioned at various angles to capture whatever comes into view. A technician directs the work from a small computer on the ground. It took just two days to scan the entire exterior, picking up every tiny crack. Interior scans were done earlier this year.

Tudor Place consists of the mansion and 5½ acres that once covered an entire block. Six generations of the Peter family — Martha Washington’s descendants — lived there in elegant splendor, catering to Washington society of every era until 1983. Thomas Peter was son of the first mayor of Georgetown and husband of Martha Custis, granddaughter of Martha Washington.

Among many key findings, Mrs. Shafagoj says the renovators have learned that the east wing, now a visitors center, at one time apparently functioned as a stable. They are beginning to “really understand how all the rooms were used by the … family and what restrictions were imposed on architect Thornton by the landscape as well as by buildings that existed on the property,” she adds.

The site’s three-year, $3.5 million improvement plan began with a drainage replacement project in 2006. The current phase is known as the stucco-replacement project. Electrical and mechanical systems are to be tackled in 2008 and 2009. Architectural conservation tours led by Mrs. Shafagoj will take place for the duration at 3:15 p.m. every Friday for $4.

The stucco has been an especially troubling issue, with a long history of its own related to the challenges involved in preserving the Federal style home for future generations. The building was constructed in phases between 1795 and 1816 and completed in 1914.

A lime-based stucco cladding, scored to look like stone blocks, was put on in 1816, in part to make the exterior of the building appear as a unified whole and hide the different periods of the building. Such stucco was known to have a life span of 50 years and so was replaced by the building’s owner in the early 1870s. However, ivy growing on the north side dislodged chunks of the stucco and helped lead to water infiltration within the walls.

Instead of lime-based stucco, preferred because it moves with the underlying masonry, an owner in the early 20th century applied Portland cement stucco atop an expandable ribbed metal lath nailed onto the masonry. He thought that approach would stop the water damage, but instead, the combination made it worse. Portland cement is rigid and doesn’t breathe in reaction to temperature changes the way lime-based cement does. This causes the bricks underneath to crack.

In addition, the metal lath made pockets between the stucco and the bricks that trapped water from condensation inside the walls. By 1918, cracks showed up in the Portland cement stucco, enabling rain to enter and get trapped against the bricks.

The problem is a familiar one to any homeowner trying to understand cracks and blistering.

“People have old houses with moisture problems and don’t know why,” Mrs. Shafagoj says.

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