Traditional Masonry Archives — Guest Columnist

Louisiana's Old State Capitol Building
Renovating the Old Louisiana State Capitol Building required removing a century of disastous repairs including the removal of elastomeric paint and an undocumented previous restoration of a skim-coat of portland cement applied over the lime mortar plaster.
by Jerry M. Campbell, AIA
President, Jerry M. Campbell & Associates, Baton Rouge, La.

In 1847, Baton Rouge lured Louisiana’s Capitol away from the city of New Orleans with the donation of a plot of land high on a bluff overlooking the Mississippi. The bluff was the fabled location of the red pole, the “baton rouge,” that French explorers claimed marked a Native American council site. Architect James Harrison Dakin (1806-1852), a New York native with a thriving practice in New Orleans, was retained to design the new Capitol Building. Over his 20-year career, he contributed significantly to the Greek, Gothic and Egyptian revival movements in the United States, and indeed an early drawing suggests he was thinking of a Greek revival building for this site. In the end, however, a magnificent Gothic-style building was erected.

Dakin described the building as “Castellated Gothic” because of the cast-iron decoration of its crenellated battlements and turrets. The building’s construction started in 1847 and ended in 1852, the same year of Dakin’s death. It featured heavy masonry walls covered with lime mortar plaster scored to resemble stone blocks. Used as a Union prison and garrison during the Civil War, it actually caught fire twice. The ruined interior was completely reconstructed in 1882 by architect and engineer William A. Freret, who installed the signature grand staircase leading upward to the stained glass “lantern” or dome that blossoms at the top of the central atrium. The building now houses a historical museum.

The exterior has undergone various renovations and repairs for cracks and leaks. Ironically, most of these “improvements” contributed to faster and more catastrophic failure. The original brick and plaster were soft and breathable, allowing moisture vapor to move in and out. When patches were later applied, they were made of harder materials that trapped the moisture and prevented natural expansion and contraction. The result was more cracking and, ultimately, structural damage.

The most recent attempt to bridge the cracks was the application of an elastomeric paint. However, the result was the encapsulation and eventual deterioration of the lime mortar plaster. When this happens, the elastomeric paint has no sound surface to adhere to and begins to delaminate and peel.

Our firm was retained by the State to remove the elastomeric paint and restore the lime mortar plaster. We began by sounding out the building — tapping the membrane paint with a small hammer. A sharp “ping” meant the underlying plaster was still sound. A dull thud identified spots where the plaster had de-bonded from the substrate.

The surprise came when we began removing the elastomeric paint. We discovered that in an undocumented previous restoration, a skim-coat of portland cement had been applied over the lime mortar plaster. We sampled the whole building and found the cement was everywhere. At this point the scope of the project changed significantly. Instead of using chemical stripping materials to dissolve and remove the elastomeric paint, the contractor, Cangelosi Ward General Contractors LLC, Baton Rouge, La., had to chisel off the entire plaster surface, including the original lime plaster material, due to the tenacious bond of the portland materials. The work was difficult. The old plaster was removed by hammer and chisel. While this eliminated the problem of chemical exposure and disposal, the added labor increased the project cost. Once again, previous renovations took their toll. Where the cement was applied over the original plaster it came off easily, but where it covered a cement patch it was difficult to remove.

With the original brick finally exposed and cleaned, the masonry was ready to receive a fresh coat of traditional plaster. The original plaster was analyzed and the formula replicated by the supplier, U.S. Heritage Group, Chicago. The material was delivered to the site pre-mixed and ready to use with nothing to add but water.

The state’s commitment to do the job right extended to bringing in a historic masonry specialist, John Speweik of the U.S. Heritage Group, to introduce the historic material and train plasterers on how to apply it. The consistency of traditional lime mortar is different from cementitious materials used today. It is like thick putty, with a feel that the local paper described as “Creole cream cheese,” making it appear too dry by today’s standards. It was essential that the consistency was maintained and the material not be overly diluted with water or additives to try to achieve a more familiar feel. Speweik further warned that the mortar is next to impossible to clean off other surfaces, so extra care was taken to protect sills and overhangs. Traditional lime mortar plaster cures much more slowly than modern materials, so that had to be built into the schedule.

Lime mortar plaster adheres to the wall because of a mechanical process, so joints were scraped into the masonry to form a key. When the mortar was troweled on, it locked into the joints. We had some real craftsmen on this project, Lloyd Moreau LLC out of Pineville, La., and they did excellent trowel work. All the workers put their hearts and souls into this — you could tell people were excited. If it wasn’t right, they made it right. Now they can tell their grandchildren, “I worked on that building.”

Using traditional mortar was not a decision based only on sentiment or a desire for historical accuracy. The building was failing because the original product was circumvented. The bricks of the day were soft and soaked up water. Fortunately, Dakin set a foundation of granite so water couldn’t migrate from the soil, but the bricks still needed to breathe. Lime mortar plaster allows that to happen. It is the best material for this building.

Eventually, the Old State Capitol will have to be plastered again. Over time, the plaster will stress and crack because the perimeter band and window surrounds made of cast iron layered with brick have a different coefficient of expansion than the masonry walls. But next time, the restorers will know just what they are working with. They will also be able to refer to the video and digital pictures taken throughout the two-year process.

There were many other facets to this major restoration, from repairing and painting the cast iron a custom color, “Dakin Brown,” to erecting a permanent scaffold so the lantern can be cleaned periodically. The Old State Capitol is a showplace and it deserves to be preserved. Fortunately, the state of Louisiana is sympathetic to restoration and preserving history, and now they have a beautifully restored Old State Capitol to show for their efforts.

TM