It’s any pedestrian’s worst nightmare — suddenly, part of a building breaks away overhead and falls onto the sidewalk.
 This exact scenario played out on St. Charles Avenue one night in August 2014: A five-foot-wide piece of the marble cornice atop Gallier Hall broke off and came crashing to the ground, smashing some of the building’s granite steps.
 Luckily, it happened around 4 a.m., and the steps were the only victims.
 But the incident shook officials at City Hall. It had been evident for some time that the circa-1853 Greek Revival-style structure, which is owned by the City and is one of New Orleans’ most revered historic buildings, needed work, but no one anticipated such outright structural failure.
 Officials roped off the sidewalk surrounding the building to keep pedestrians safe, and called Tulane University for help.

 The School of Architecture pointed them to Cypress Building Conservation, a local company that has done structural analysis work on buildings owned by The Historic New Orleans Collection and others. “We were brought in to do a conditions assessment report,” said Michael Shoriak, who owns the company with partner Courtney Williams. That conditions survey, which included a glossary that defined the different ways deterioration was happening across the building, morphed into a scope of work that the city’s Director of Capital Projects, Vincent Smith, was able to use to direct stabilization of the building.
 What Shoriak and Williams found was disturbing. Wrought-iron pins that had secured the façade’s marble blocks and decorative elements for 150 years were corroding, making the stone on the building unstable, capable of falling at any time. They also discovered that the marble comprising the entire façade wasn’t a true marble at all, but instead an inferior stone whose faults also made pieces capable of separating from the building and falling to the ground. “Any stone could fall at any time,” Shoriak said. “When we realized that, the project changed — this wasn’t just about one problem stone, but a systematic issue across the entire surface of the building that needed to be addressed in a major way.”

Gallier Hall, one of the finest buildings ever designed by famed architect James Gallier, with two impressive rows of fluted Ionic columns and winsome sculptures in a decorative frieze above the portico, faces Lafayette Square on St. Charles Avenue in the Central Business District. It served as City Hall for over a century, and is now considered to be one of the city’s most revered landmarks.
 It wasn’t always so. City officials thought the building was useless after City Hall moved to its current location on Duncan Plaza in 1958, and they proposed demolishing the structure. One of the early advocacy efforts of the Louisiana Landmarks Society was to ensure that Gallier Hall was saved from the wrecking ball.
 Luckily, the efforts were successful, and Gallier Hall escaped demolition. It was named a National Historic Landmark in 1974, but city officials still neglected to put much effort into the building’s maintenance in the second half of the 20th century. When the building needed stone replacements, stone was chosen that didn’t match the rest of the façade, so workers simply painted the whole front of the building with a cement wash to keep the color uniform, Shoriak said. For decades, the building’s true color has been concealed by this gray wash, which is an inappropriate material covering that clashes chemically with the historic structure’s original materials.

 Cypress Building Conservation worked with architect Mark Reynolds of Mark Design LLC to come up with a stabilization plan by understanding what exactly was wrong with the structure. “The story starts 500 million years ago,” Shoriak said. “The building is made of Tuckahoe marble, sourced from New York state, according to the original documents. But Tuckahoe marble is not a true marble. Four hundred and fifty million years ago it started metamorphosing into a marble, but it didn’t finish the process.” Instead, this stone contains fault lines and large, porous grains. “That opens up all different possibilities for negative things to happen,” he said. “Tuckahoe marble was being sold as true marble because it could take a polish. This didn’t just happen in New Orleans — buildings in Philadelphia, New York and across the country were made with this stone, and the problems with those buildings have been documented.”
 Shoriak and Williams worked with Atkinson-Noland Engineers, who conducted ultrasound testing to look for inconsistencies in the stone. Every single stone they tested had fault lines, Shoriak said.
 Instead of proposing that all of this faulty stone be replaced, which would have been financially impossible, the group worked together to devise a way to anchor the Tuckahoe marble stones to the building securely and permanently.
 “The engineers designed a system for pinning the cornice stones where two-foot-long cores were drilled by a masonry subcontractor through every single cornice stone,” Shoriak explained. “All of the faulty wrought-iron pins were replaced with stainless steel rods, and then the holes were injected with epoxy and grout, which expands to hold the stainless steel pins in place.” Over 350 pins were used to secure the Tuckahoe marble blocks and decorative elements covering the front of the building. “The way the system is designed, the stainless steel anchors are self supporting,” he said. “So now every single stone could crack, and would have fallen before, but now will be held in place no matter what with the pins.”
 Local contracting firm Battco Construction managed the on-site work and brought in specialists from Detroit to assist. They built scaffolding across the entire front of Gallier Hall and put workers on shifts around the clock. Though they began work in September 2015, Smith wanted the project complete in time for Mardi Gras 2016, as Gallier Hall is historically the location where the mayor and other city officials watch the parades. “We worked double shifts, worked through the night, through Thanksgiving, Christmas and New Years, and we actually ended up finishing the project up right on time, in January,” said Joey Battaglia, Battco Construction’s president.
 “It was a tough job — it was confined quarters up on that scaffolding, and we had the streetcar running constantly,” Battaglia said. “We had to keep the Lafayette Street alleyway open for condo parking access next door, there was filming going on for a Tom Cruise movie…a lot of logistics went into accomplishing this job on time.”
 “I give a lot of credit to Battco. They stepped up on this fast-track project,” Smith said. Mayor Mitch Landrieu, city leaders and constituents were able to safely enjoy Mardi Gras parades this February from stands on Gallier Hall’s portico.

testing the micro abrasive cleaning system on gallier hall. Look at that cementitious coating coming right off!! #gallierhall #masonry #conservation

A video posted by material analysis+restoration (@cypressbldg) on Oct 13, 2015 at 2:07pm PDT

Though Shoriak and Williams are quick to point out that this project was a stabilization, not a restoration — “The building still has the wear and tear of 150 years, as it should,” Williams said — some of the work they planned for the building had the added benefit of beautifying the structure simultaneously.
 This included a thorough micro-abrasion cleaning of the building. Gallier Hall’s Tuckahoe marble had been mistreated in past cleanings, Shoriak said, through methods like acid washes and sand blasting. Shoriak and Williams wanted to avoid any cleaning method that could further damage the stone, however. “In micro-abrasion, you use a material softer than the one you’re cleaning,” Shoriak explained. The method they recommended is only done by two companies in the world. Battco located machinery sold by an Italian company and rented it to complete the work. Silicate glass, which is softer than stone, was blasted out of the machine in all directions to gently clean the cement wash outer layer off the building. “The pressure being used was very low — you could stick your hand in front of it,” Shoriak said. But it was enough to send the gray cement wash flying, revealing white stone that hadn’t been seen by human eyes in decades.
 Cypress found stone to match the historic Tuckahoe marble and replaced the past Dutchmen, or stone patches, that had been put in over the years. This time, however, the effort was made to properly match the color. They also recommended the re-pointing of the building’s mortar with natural hydraulic lime, and the application of a clear consolidant to the stone — a chemical that, while invisible to the human eye, “penetrates deep into the historic stone and glues everything back together,” Shoriak said.
 “I think that was our true role in this project: Bringing a knowledge of which compatible materials to use on this historic building,” Williams said.

doing/watching low pressure micro abrasive cleaning is kind of addictive #masonry #conservation #gallierhall

A video posted by material analysis+restoration (@cypressbldg) on Oct 15, 2015 at 9:08am PDT

The work of Cypress Building Conservation, Battco, and others whose efforts led to the sparkling white marble façade that now greets visitors of Gallier Hall is not yet over — not even close. Though the front façade has been stabilized and cleaned, three more sides of the building need the same work.
 The front of the structure is made entirely of Tuckahoe marble, Shoriak said, while the sides have marble dentils and decorative elements above stucco scored to look like stone. Phase two will entail stabilizing these elements with the same stainless steel pinning used on the front, as well as the same cleaning and care for the materials.
 Both phases of this project, as well as efforts to restore the building’s interior, are detailed in a comprehensive plan for Gallier Hall that was crafted before this work began, Smith said. He estimated the total cost to be $15 million.
 Though the City is covering some of this expense, significant fundraising is needed to pay the balance. A fundraising committee chaired by New Orleans’ First Lady Cheryl Landrieu is working to see that the money is raised and the restoration is complete by 2018, in time for New Orleans’ tricentennial.
 “On the interior, we will restore windows, chandeliers, paintings, millwork and wiring,” Landrieu said. “The bathrooms will get facelift.” Though the building’s historic beauty is awe-inspiring, she said, years of deferred maintenance mean there is much work to be done to restore Gallier Hall’s interior — $5 million worth, she estimates.
 The goal, she said, is to restore its former grandeur while also revitalizing its underused spaces, such as a first floor theater, to make the building more accessible and serviceable to the community. “We’re witnessing a revitalization of the whole downtown area…we could use Gallier Hall for so many more events, and as a community space if we could get it up and running,” she said. “It’s kind of run down, but it’s such a beautiful space with history, and people in New Orleans love authentic spaces.”
 A “small but strong committee” is currently raising funds for the work, and there is “huge interest” in helping revitalize the building, she said. “I’m not surprised that people want to donate and be involved,” she said. “It’s a gem. People are stunned by the beauty and potential of it.
 “We have a lot of work to do to get word out and get people involved, but this is a gift to our city,” she said. City officials restored St. Louis Cathedral to celebrate New Orleans’ bicentennial, she said, so it is fitting that Gallier Hall should be the restoration recipient for the city’s 300th birthday. “This will be a legacy project,” she said. “The tricentennial gives us a good reason to take the time to really take good care of this structure.”

Click here to read the rest of the April 2016 issue of Preservation in Print.