Temple undoomed

Wright's Unity Temple tests concrete's endurance

January 01, 2001 |

Unity Temple in Oak Park, Ill., one of Frank Lloyd Wright's most significant public buildings, is teetering on the brink of extinction. An early example of the use of reinforced concrete, the 1909 structure suffers from water infiltration, crumbling concrete and a host of other ills.

Fortunately for the landmark-and for Christine Happ Olson, new executive director of the Unity Temple Restoration Foundation (UTRF)-the state department of commerce has granted more than $1 million for badly needed exterior work. But the project is complex, says Olson, requiring a major HVAC upgrade and interior and other restoration totaling up to $3.3 million.

"It's a retrofit to the nth degree," sighs Olson, but she remains optimistic. In February, Construction Technology Laboratories Inc. (CTL) of Skokie, Ill., will begin the unusual design/build exterior reconstruction, and the village will pitch in as much as $32,000 for M/E engineer Cosentini Associates to design a new HVAC and dehumidification system.

Still, this work and the funds will only pay for one the project's three phases.

The concrete stabilization is critical, however, says William R. Crozier, co-chairman of the UTRF, as large chunks of material have fallen recently from the temple's heavy cantilevers. Carbonation of the material-both inside the temple hall and on the exterior planes-is the primary cause of deterioration, he says.

Past efforts

In the 1970s, the exterior was restored with shotcrete, but while the color and texture matched well and the material held, the aggregate contained iron, which caused rust-colored spots and streaks.

According to Thomas L. Rewerts, vice president of CTL, the concrete upgrade will seal cracks in the "parent concrete," rebuild visibly sagging cantilevered roof slabs and patch spalling caused by corroded steel. The plans call for unusual materials, including a Silane cream sealant and an "expansive grout" called Bristar for removing concrete under the cantilevers without using impact tools that could damage original cinder concrete and historic art glass windows. "The biggest challenge is to match the color of the original concrete," says Rewerts.

Inside the "auditorium," other challenges await, Crozier adds, such as the removal of retrofitted radiators and pipes. Wright's original design called for one of the first-ever forced-hot-air heating systems-and self-melting roof drains-but neither system ever really worked. "We want to restore the interior so that visitors can experience the space as Wright intended," says Happ Olson.

Of greatest historic urgency, however, is water damage near original wood trim. Some carbonation is caused by human respiration, but the main cluprit is clear. "With 14 flat roof planes and seven skylights, it's hard to understand why there'd be water infiltration," Crozier jokes.

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