Craftspeople Restoring Jefferson’s Plaster Ceilings to the Lawn Colonnades

“The ultimate goal is returning the Lawn to its appearance from the original construction period as Thomas Jefferson would have known it,” said James Zehmer, senior historic preservation project manager with Facilities Management’s capital construction and renovations’ department. “And a plaster ceiling at the colonnades is part of that appearance.”

Recently, plasterers Brent Ryder, Brian Helmick, Robby Kolb and Walker Shifflett stood on a scaffold, working above their heads to carefully slather a second layer of plaster onto the “scratch coat” – so called because it is scored to give the second application something to which it can adhere.

They worked in sections, applying the plaster, then smoothing it with a long, aluminum screed. Each layer cures for several days before the next application is made. After the first two coats dry, a thin, smooth finish coat is applied. The finished, lime-based plaster breathes and will not need painting.

Among the modern equipment being used is a mixing machine that makes the basic lime plaster. The workers then mix in goat hair – a binding agent that is not visible in the finished product – by hand before applying it to the ceiling.

In the first ceiling restoration between pavilions VII and IX, the workers used metal joists to hold the metal lath – basically a heavy-gauge screen – for the ceiling structure.

“After that we switched to wood joists and wood lath for a more traditional approach,” Zehmer said. “But what we found is that while we used a more traditional approach, it gave us a more traditional appearance, and there was a lot of cracking. So, in the spirit of learning from ourselves, we’ve switched back to metal joists and metal lath, which won’t expand and contract with humidity and twist and turn, which is what was happening on some of our other ceilings.”

The metal lath makes a good surface to hold the plaster.

“The wire mesh has a rib in it, which adds rigidity and structural support,” Zehmer said. “It is screwed tight in a regular pattern to the ceiling joists. And then wherever they overlap, they use a piece of wire and stitch it together to the next piece just to make sure we don’t have any little sags or funny edges. When you push the first coat of plaster up into the metal lath, it does what’s called keying. The plaster squishes through the lath and then reconnects with itself. And so the goat hair helps in that process, in that it gives a physical binder. It’s not just the wet mud of the plaster holding it up there.”

Matt Proffitt, the historic mason supervisor, said the plaster takes 45 days to fully cure.

Initially, the work crews tried to repair the colonnade roof and build the ceilings at the same time, but soon found that did not work.

“Because the plaster is really susceptible to vibrations, we learned pretty quick that we couldn’t have people working on the roof project at the same time,” Zehmer said. “And it was actually pushing the project way into the fall, to the end of October in some cases. And we really felt like that wasn’t fair to the Lawn students.”

The workers now alternate, restoring a roof and rail one year and then plastering the ceiling underneath the following year. Last year, the historic carpenters restored Jefferson’s flat roof and railing over the colonnade between pavilions VIII and X.

Proffitt enjoys the sense of historic place in the work he is doing.

“I like the historical side of it,” Proffitt said. “It’s gratifying doing something where we are bringing it back to the idea Jefferson had for this place and restoring it to what it looked like in the 1820s.”