High-tech tools help preserve the High-tech tools help preserve the pastpast

Presented By:Presented By:

Ar: Noha Mohamed Effat HessianAr: Noha Mohamed Effat Hessian

by Alan Jochby Alan Joch

Archrecord.construction.com/features/Archrecord.construction.com/features/digital/archieves/digital/archieves/

7070

July 2003July 2003

High-tech tools help preserve the pastHigh-tech tools help preserve the past

the iconic residence in western the iconic residence in western Pennsylvania, Frank Lloyd Wright’s Pennsylvania, Frank Lloyd Wright’s Fallingwater had a dirty little secret. That Fallingwater had a dirty little secret. That is its terraces that hover over Bear Creek is its terraces that hover over Bear Creek seemingly defy gravity, But those terraces seemingly defy gravity, But those terraces were only temporarily fighting off gravity’s were only temporarily fighting off gravity’s pull .pull .There were fears that the terraces would There were fears that the terraces would eventually fail during construction of the eventually fail during construction of the house, but no one knew the full extent of house, but no one knew the full extent of the danger until the mid-1990s. the danger until the mid-1990s.

Engineers were capable of evaluating this Engineers were capable of evaluating this historic treasure with the help of special radar historic treasure with the help of special radar devices and innovative measurment tools devices and innovative measurment tools that that daily recorded the movements of microscopic daily recorded the movements of microscopic surface cracks, and they concluded that The surface cracks, and they concluded that The main terrace had sunk 7 inches in 60 years. main terrace had sunk 7 inches in 60 years. Fallingwater wouldn’t be around for another six Fallingwater wouldn’t be around for another six decades unless it underwent drastic structural decades unless it underwent drastic structural renovation .renovation .An $11 million preservation effort is now An $11 million preservation effort is now underway to make the building structurally underway to make the building structurally sound and to fix more than 60 leaks that have sound and to fix more than 60 leaks that have warped doors, peeled paint, and stained interior warped doors, peeled paint, and stained interior walls by the means of non destructive testing walls by the means of non destructive testing equipments and High –tech computer models equipments and High –tech computer models

These technologies used by chemists and These technologies used by chemists and metallurgists for years, are now being adopted to metallurgists for years, are now being adopted to gain a complete understanding of a building’s gain a complete understanding of a building’s condition while causing the least amount of condition while causing the least amount of damage. damage. Historic preservation is on the rise both for the Historic preservation is on the rise both for the intrinsic value of maintaining architectural intrinsic value of maintaining architectural treasures and for economic reasons .treasures and for economic reasons .In addition to knowing the intricacies of In addition to knowing the intricacies of preservation standards, architects need to preservation standards, architects need to understand the construction methods and understand the construction methods and makeup of historic buildings inside and out, often makeup of historic buildings inside and out, often without the benefit of original design drawings. without the benefit of original design drawings. No matter how advanced technology becomes, No matter how advanced technology becomes, the first step in assessing a building’s health the first step in assessing a building’s health remains visual inspection. remains visual inspection.

Architects then may use rectified photography to Architects then may use rectified photography to help assess a building’s condition. Rectified help assess a building’s condition. Rectified photos are manipulated during the printing photos are manipulated during the printing process for perspective, so that horizontal and process for perspective, so that horizontal and vertical edges aren’t marred by parallax vertical edges aren’t marred by parallax distortions (most CAD software does this distortions (most CAD software does this automatically). automatically). Other tools include X-ray devices that determine Other tools include X-ray devices that determine the structural components of wall sections the structural components of wall sections without having to drill into them. When surface without having to drill into them. When surface cracks appear, motion monitors track the almost cracks appear, motion monitors track the almost imperceptible sagging in historic structures over imperceptible sagging in historic structures over time. The monitors use small wire segments that time. The monitors use small wire segments that span cracks and register minute movements as span cracks and register minute movements as cracks expand and shrink due to temperature cracks expand and shrink due to temperature fluctuations or settling. fluctuations or settling.

Architects also use thermal imaging systems to Architects also use thermal imaging systems to peer inside historic structures to depict peer inside historic structures to depict temperature variations through color temperature variations through color gradations, thus showing where leaks in a gradations, thus showing where leaks in a facade, window, or other structural element facade, window, or other structural element may lead to unseen internal deterioration. may lead to unseen internal deterioration. Cooler areas indicate where water has Cooler areas indicate where water has penetrated. penetrated.

Software that assists in nondestructive Software that assists in nondestructive evaluation highlights where leaks have evaluation highlights where leaks have occurred in a facade (the blue areas show occurred in a facade (the blue areas show where water has penetrated where water has penetrated

Engineers relied on a structural analysis Engineers relied on a structural analysis program from software maker SAP AG to model program from software maker SAP AG to model the building’s settling pattern. Motion monitors the building’s settling pattern. Motion monitors logged data on cracks in the concrete for a year logged data on cracks in the concrete for a year and a half, and the staff then plotted seasonal and a half, and the staff then plotted seasonal fluctuations in the sizes of the cracks as well as fluctuations in the sizes of the cracks as well as overall movement trends. To bolster this data, a overall movement trends. To bolster this data, a surveyor pinpointed elevations along the surveyor pinpointed elevations along the parapets, and these numbers were compared to parapets, and these numbers were compared to those on the original drawings. Taken together, those on the original drawings. Taken together, the data showed a slow, steady sagging of the the data showed a slow, steady sagging of the terraces from their original positions. terraces from their original positions.

While the data revealed stress points, While the data revealed stress points, technology couldn’t answer the question on technology couldn’t answer the question on everyone’s mind: How much longer would it be everyone’s mind: How much longer would it be before Fallingwater’s terraces failed? Stories before Fallingwater’s terraces failed? Stories had surfaced during Fallingwater’s construction had surfaced during Fallingwater’s construction that the reinforcement of the concrete terraces that the reinforcement of the concrete terraces specified by Wright was inadequate, and rumor specified by Wright was inadequate, and rumor had it that the builder doubled the number of had it that the builder doubled the number of reinforcing rods Wright had called for, but no one reinforcing rods Wright had called for, but no one could verify this claim. could verify this claim.

They inspected the reinforced concrete using They inspected the reinforced concrete using impulse radar, and used a transducer to send a impulse radar, and used a transducer to send a radar wave into the concrete, which reflected the radar wave into the concrete, which reflected the wave back to the surface when it detected wave back to the surface when it detected reinforcing steel. The transducer sent readings reinforcing steel. The transducer sent readings to a data recorder, which then created a rough to a data recorder, which then created a rough image of the underlying structure. image of the underlying structure.

Engineers compared these readings to the Engineers compared these readings to the original drawings. The result: The builder did original drawings. The result: The builder did double the reinforcing .double the reinforcing .

Under the microscopeUnder the microscope

If the engineers suspect a problem with a If the engineers suspect a problem with a particular material, they send it to the lab for particular material, they send it to the lab for analysis, for Fallingwater; The lore of the house analysis, for Fallingwater; The lore of the house was that the exterior and the interior were was that the exterior and the interior were painted the same color, they collected paint painted the same color, they collected paint samples and sent them for analysis to an samples and sent them for analysis to an outside testing lab, where technicians were able outside testing lab, where technicians were able to determine the number of paint layers that had to determine the number of paint layers that had been applied to the interior, the chemistry of the been applied to the interior, the chemistry of the paints, and their exact colors. paints, and their exact colors.

But they found out that But they found out that someone repainted the someone repainted the interior a much lighter shade. interior a much lighter shade.

They knew that They knew that quickly because the analysis quickly because the analysis showed very little dirt trapped between the first showed very little dirt trapped between the first and second paint layers.and second paint layers.

Similar to Similar to Fallingwater engineers Fallingwater engineers used the lab on an ongoing used the lab on an ongoing restoration of New York’s restoration of New York’s Metropolitan Museum of Art’s Metropolitan Museum of Art’s facade on Fifth Avenue. Samples of facade on Fifth Avenue. Samples of its Indiana limestone went to the its Indiana limestone went to the lab, where analysis revealed that lab, where analysis revealed that problems around the mortar joints problems around the mortar joints weren’t allowing water to escape off weren’t allowing water to escape off the facade quickly enough. Lab the facade quickly enough. Lab technicians determined that the technicians determined that the cement-to-limestone ratio in the cement-to-limestone ratio in the mortar contained too much of the mortar contained too much of the former. Architects are now former. Architects are now repointing the area with a more repointing the area with a more effective composition. effective composition.

The Fifth Avenue facade of the Metropolitan Museum of Art,

conclusionconclusion

Architects Architects believe that nondestructive believe that nondestructive diagnostics will become even more important in diagnostics will become even more important in the years ahead. They allow preservationists to the years ahead. They allow preservationists to surgically find and fix hidden problems without surgically find and fix hidden problems without causing excessive damage. “Because we’re causing excessive damage. “Because we’re more educated about how to evaluate existing more educated about how to evaluate existing buildings, it costs the same or less to fix one buildings, it costs the same or less to fix one that’s already standing than to build a new that’s already standing than to build a new building building