A building sealant once billed as an efficient alternative for protecting old buildings has now become the bane of preservationists, as a product expected to protect structures has been identified as a strong contributor to their demise.

While innovation may be good for Playstation or NASA, it can often be doom for historic preservation. Architect Joseph Opperman says that efforts to try new methods of preservation in the 20th century worked against the good practices of the past.

“These problems are self-inflicted,” he says.

Back in the ’60s and ’70s, building owners looking for ways to trim maintenance costs stumbled upon the elastomeric sealant that was expected to protect a building from moisture. Compared to traditional lime wash sealants that had been used for nearly 200 years, the elastomeric didn’t have to be replaced as much.

“It was a common practice,” says Robert Gurley, assistant director of the Preservation Society of Charleston. “People thought they were doing a good thing. What they didn’t know was that it doesn’t allow the building to breathe.”

As restoration projects weave their way through the city, the elastomeric has been a consistent foil, locking in the moisture that naturally builds up in these old buildings that would normally seep out of the side of the building, if not for the extremely powerful sealant. Holding it in will eventually rot away the bricks and mortar that the sealant was meant to protect.

Gurley says it’s hard to tell how many historic downtown buildings are covered in the sealant, but several high-profile restorations have been undertaken to repair the damage done to exterior walls because of the elastomeric.

The latest restoration project plagued with elastomeric troubles was the restoration at the Madren Building at 177 Meeting St., the office and retail building that shares a block with Wachovia. More than 160 years old, the building housed the Madren Paint Co. for 45 years until 1995, and it was during that time that the building got its fresh coat of catastrophe.

When Opperman started work at 177 Meeting, he had already faced problems with elastomeric during restorations at the Market Hall and St. Mary’s Church. These buildings are made of fairly soft, hand-made bricks that collect moisture and need to expel it, Opperman says, and the heavy sealant was like a choke hold.

“It starts to take off the surface of the brick,” he says.

American Financial Realty Trust, the company that owns 177 Meeting Street, spent two years working on the restoration of the building, most of which involved removing the elastomeric, repairing the bricks, and replacing the doors and window frames damaged from the trapped moisture, says Tony DeFazio, spokesman for the trust. He wouldn’t say how much the work cost, only that they had to be “extraordinarily focused and attentive” and that “when you do the job right in Charleston, it takes money.”

That spending is already paying off. The building won the Preservation Society’s Carolopolis Award for exterior preservation and looks to soon increase the building’s leased space from 73 percent to 93 percent.

While paint companies will note that improvements have been made to elastomeric and that it’s suitable for some newer buildings, Gurley says that damage to Charleston’s historic buildings is a hard lesson that preservationists should not soon forget.

“That’s our concern about new materials being applied to historic buildings,” he says. “We need to be cautious.”

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