One of the nation’s oldest plantation houses is getting a face- lift in hopes that it’ll look just like it did 40 years ago. Built in 1739, Drayton Hall was remarkably preserved by its founding family for generations before it was sold to the National Trust for Historic Preservation in the 1970s. But requirements that the building be left in the shape it was when handed over has provided unique challenges for the Trust. It’s the thin line between restoration and preservation.

“Drayton Hall is being preserved ‘as is,’ so you’re constantly trying to figure out how to save the house and do a lot of work without looking like you’re doing anything at all,” says Matthew Webster, the site’s preservation director.

Work under way includes replacing crumbling mortar at one corner of the home. While most of the original 18th century mortar is holding strong, one corner had been replaced with lesser quality mortar that hasn’t held up. So the crew is going back to the traditional methods and limestone materials used when the house was first built, bucking the philosophy that newer is better.

“Newer doesn’t always get along with older buildings,” Webster says. “The mortar has worked for over 200 years, and it’s still here.”

Stone crumbling on the edges of the front stairs also was repaired — again, with an eye toward appearing seamless with the larger, original stone.

The largest work involves repairing a stone arch over the basement patio. Structural changes to the arch over the years, including a cement barrier that locked in moisture, has overstressed the arch and caused it to snap. Crews will be temporarily removing the outer stone and pulling the arch back into place.

The necessity for modern fixtures to secure the arch, an oddity for this “unchanged” site, make it particularly challenging, Webster says.

“Anything that we do, we want it to be reversible,” he says. “In 20 years, we might have the technology to do this in a completely different way. We want it to last, but at the same time we want the ability to remove it without doing damage.”

The use of modern materials like stainless steel also ensures the project won’t be over when the work is done. “You always have to watch it to make sure the structure doesn’t react negatively,” Webster says.

If there’s one thing that Drayton Hall’s architects had in mind, it was incredibly ornate, beyond-geeky attention to the house’s internal structure. The level of detail in each room dictates its importance in terms of classical architecture, beginning with the low-level design of the porch to the slightly improved front room. The design then increases in significance as it moves up the staircase, through the second floor doorway and into the highly detailed grand room above.

“They’re showing you exactly how to progress through the house,” Webster says. “It’s amazing the level of detail they put in the house. It’s completely over the top.”

Drayton Hall is different from your average historic home, like Jefferson’s Monticello or Washington’s Mount Vernon, because the home has intentionally been left unrestored, meaning that the house’s history isn’t buried under layers.

“With most of our house museums, you’re dealing with microscopic information, like with the paint,” Webster says. “With this house, the same paint is still on the walls.”

Another lesson of the house is the little details that have been added over the years, like the hardware that spans from the house’s origin to the mid-1800s. In one room, there are door hinges that suggest carpeting, while a mantel in another room is too fancy and oversized for the wall’s original design.

“If you’re going to go back in time (with a restoration), you’ve got to wipe out all the other information. This house is showing you the layers, so you’re not going to be stuck in time.”

Well, not until the 1970s. But the wealth of touchable artifacts doesn’t make the work any less challenging.

“There’s a lot we have to figure out here,” Webster says. “People think that we know everything about this house because it’s been a museum since the 1970s, but it has so many secrets left to tell.”