One of masonry's greatest strengths is its great strength, but eventually deterioration makes repair work necessary. If the owners of the building want to, or are required to, restore the building to its original appearance, then the project may become a historical restoration.

Nearly any building more than 50 years old may be eligible for listing by the National Register of Historic Places. Once listed, a building is given guidelines for restoration work, usually overseen by a local or state preservation administration.

Although federal laws specifically state that "owners of private property listed in the National Register are free to maintain, manage, or dispose of their properties as they choose, provided that no Federal monies are involved," significant tax advantages usually make it worth the effort to not jeopardize a property's eligibility.

Successful historic restoration comes from a knowledge of and willingness to follow all of the rules, but more importantly from what restoration expert Mike Schuller, Atkinson-Noland Associates, Boulder, Colo., calls "a different mind set." Says Schuller, "Since there were no codes [originally], the designer started with engineering basics and a knowledge of the mechanics of the materials, then applied some rules of thumb. After that it was mostly the mason who determined how things went together."

Restoration contractor Rich Schultheis, Premier Specialty Contractors, Denver, Colo., says that "one of the most difficult things can be keeping everything stabilized above while we're putting in new materials." Restoration architect Marc Harary, Fuller and D'Angelo, Elmsford, N.Y., agrees that "this work is absolutely a collaborative thing."

As the building is opened up, unexpected damage is often found, which makes bidding a challenge. Schultheis says, to bid a historical job, "figure out what you think it will cost, then double it."

Returning a historical building to its original condition means removing the minimum amount of damaged materials and replacing them with materials as similar as possible. "Knowledge of the properties and performance of these historical materials is critical," says John Voelker, Cornerstone Restoration, Denver.

Successful restoration contractors must be flexible and able to figure out what they are seeing as they go along and do whatever is needed. "We need to have a broad knowledge of building construction," says Schultheis. "Carpentry skills are important for building good shoring and bracing. We also have to understand roofing." Voelker feels that "the skills are so different than for modern masonry that I find it's easier to train someone from scratch." Schuller, however, feels that one of the keys is "knowledge of how things were done in the old days. The best restoration contractors know the history of masonry construction. They've seen a lot of different things. They have passion for the work and they want their repair work to last another 100 years."