Q: How much renovation can be done to a building and not affect its historic value?
A: For properties listed on the National Park Service’s National Register of Historic Places, owners have four approaches to the treatment of a historic property: preservation; rehabilitation; restoration; and reconstruction.
In some cases, extensive renovation may be needed to fulfill each approach.
“Choosing an appropriate treatment for a historic building or landscape is critical,” an article on the NPS website says. “Preservation focuses on the maintenance and repair of existing historic materials and retention of a property’s form as it has evolved over time. Rehabilitation acknowledges the need to alter or add to a historic property to meet continuing or changing uses while retaining the property’s historic character. Restoration depicts a property at a particular period of time in its history, while removing evidence of other periods. Reconstruction re-creates vanished or non-surviving portions of a property for interpretive purposes.”
For properties not on the National Register, such as private homes in historic districts, the rules may vary. Since the goal of the districts is to preserve the character of the neighborhood, most restrictions apply only to exterior changes to properties.
While national, state and local organizations have their own guidelines on renovation, many adhere to rules established by National Register.
Some historic U.S. buildings have been extensively renovated. According to information on the White House Museum website, the main body of the mansion was found to be structurally unsound after President Harry Truman added a balcony to the South Portico at the second-floor level in 1948.
“Floors no longer merely creaked; they swayed,” according to the website. “The president’s bathtub was sinking into the floor. A leg of (daughter) Margaret’s piano broke through the floor in what is today the Private Dining Room.”
Engineers did a thorough examination and found plaster in a corner of the East Room sagging as much as 18 inches.
“Wooden beams had been weakened by cutting and drilling for plumbing and wiring over 150 years, and the addition of the steel roof and full third floor in 1927 added weight the building could no longer handle,” according to the website. “They declared the whole house to be in imminent danger of collapse.”
Plans were discussed to demolish the building and rebuild it to the same design. In the end, Truman went to Congress and requested the funding to rebuild the White House from the inside out, leaving only the stout brick outer walls.
“The old interior of the Residence was dismantled, leaving the house as a shell with the two modern wings,” according to the website. “Some of the existing interior detail was saved, especially fireplace mantels. Some of the scrap was sold as souvenirs. The mansion was then rebuilt using concrete and steel beams in place of its original wooden joists.”