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by Alan Joch

Frank Lloyd Wright’s Fallingwater, the iconic residence in western Pennsylvania, had a dirty little secret. The exhilarating concrete terraces that hover over Bear Creek seemingly defy gravity, their support coming from reinforcing steel within the concrete. But the terraces were only temporarily fighting off gravity’s pull, like an arm wrestler gallantly losing out to a stronger opponent.

Fears that the terraces would eventually fail surfaced during construction of the house, but no one knew the full extent of the danger until the mid-1990s. Armed with
special radar devices and innovative measurement tools that daily recorded the movements of microscopic surface cracks, engineers hired to evaluate the historic treasure came to a startling conclusion: The main terrace had sunk 7 inches in about 60 years. Fallingwater wouldn’t be around for another six decades unless it underwent drastic structural renovation. “It was in a state of stress beyond what we were comfortable with,” recalls John Matteo, an associate at the Washington, D.C., office of Robert Silman Associates, the engineering consultant.

Software that assists in nondestructive evaluation highlights where leaks have occurred in a facade (the blue areas show where water has penetrated). Image: Courtesy Robert Silman Associates

The analysis, much of it done with nondestructive testing equipment and high-tech computer models, spurred Fallingwater’s caretakers into action. An $11 million preservation effort is now underway to make the building structurally sound and to fix more than 60 leaks that have warped doors, peeled paint, and stained interior walls [Record, May 1999, page 97].

Fallingwater’s restoration needs are not unique, but the Wright site is noteworthy for the range of technological tools architects and engineers are employing. Used by chemists and metallurgists for years, these technologies are now being adopted to gain a complete understanding of a building’s condition while causing the least amount of damage.

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