Gallier Hall- St. Charles Avenue Facade Renovation

New Orleans,
Louisiana

The classical portico/ primary façade of the historic 1850 Gallier Hall building was stabilized and restored. The restoration included both structural repairs and masonry cleaning.

Gallier Hall

Originally known as Municipal Hall, Gallier Hall is named for its architect James Gallier, Sr. and served as the seat of New Orleans’ city government for over 100 years. It is recognized as one of the city’s finest examples of Greek Revival architecture and is renowned for its scholarly application of Classical details and proportions. Since the relocation of City Hall to another building in the 1950’s, Gallier Hall is now used for public special events in its splen- did main interior rooms and municipal offices in its upper stories. Prominently located on St. Charles Avenue facing Lafayette Square,

Gallier Hall occupies an iconic place in both the city’s history and its contemporary cityscape. A National Historic Landmark, Gallier Hall has been the site of many historic events and each year its portico serves as the location for the traditional Mardi Gras toast between the Mayor and Carnival royalty passing by in Mardi Gras parades.

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An Emergency Situation

In the predawn hours of the morning of August 26th, 2014, a section of marble cornice approximately 5 feet long sheared off of the façade and fell onto the granite stairs below. The stone pieces from both the façade and the granite were broken beyond reasonable repair. Thankfully, no pedestrians were injured in the collapse.

Police barricades were quickly erected to close the surrounding sidewalks and building conservation experts were retained to investigate the cause of the stone failure. It was determined that mortar loss allowed water intrusion into the joints of the porous Tuckahoe marble and caused ferrous metal anchors within the façade to corrode and expand. This expansion exacerbated the natural shearing qualities of the stone to generate large cracks, and eventually failure.

Many large cracks were observed in many areas of the façade and without repair, the prospect of additional stone failures loomed.

conservation Process

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Before Conservation

In addition to the immediate safety issue of stone failure, the investigation of the existing façade conditions found and documented many types of soiling and deterioration present on the façade.

A detailed survey of the façade documented areas of deteriorated joint mortar, dimensional loss (stone areas over 2”), cracking, displacement/deformation, incipient spalling, differential erosion, mineral inclusions, previous repairs, previous stone replacements, metallic staining, mechanical intrusions, vegetation, and soiling. The findings of the survey work were documented in color-coded drawings that became the basis for formulating repair strategies and construction documentation.

Structural Repairs

It was determined that without corrective action, the corrosion and expansion of the original 1850 ferrous metal stone anchoring hardware would lead to further failures of the stone façade.

To permanently stabilize the façade stone, an engineered pinning solution using the Gruenstarkanchoring system was designed. Hollow stainless steel threaded rods and fabric bladders were placed into core holes drilled into the existing stone. The hollow center of the rod and bladder were then injected with high strength grout.

The resulting core holes were carefully capped with a disk-shaped plug of matching marble and hand finished to match the color and texture of the adjacent historic material.

Masonry Cleaning

In the drawing at left from the bid set, a variety of cleaning techniques were planned for the façade. After on-site testing and evaluation, the building team determined that micro-abrasive cleaning was the most effective method of cleaning the façade, and this method was used over the entire façade, with selected small areas of marble receiving a poultice treatment to remove mineral staining.

The cleaning treatment resulted in a notable restoration of the bright white coloring of the Tuckahoe marble, and improvement to the appearance of the Quincy granite monumental steps and porch.

Stone Replacement

The fallen segment of the broken cornice shattered on impact with the steps below and was broken beyond repair.

A full-size wood template of the cornice profile was made from the adjacent stones and used to carve a new piece of marble.

The new marble piece was placed and anchored with stainless steel rods. The photo to the right shows the new stone immediately after it was placed. Subsequently, the stone was hand finished to distress the surface to match the adjacent 165 year old stones.

Crack and Dutchman Repairs

Cracks to be repaired were identified in the upper drawings.

The various types of Dutchmen repairs employed in the project are identified in the lower drawings.

Volute Repairs

Cracks observed in the finely carved volutes at the column capitals were individually reviewed by the design team and repair contractors. Thin masonry anchors were carefully placed at various angles depending on the pattern of the cracks.

Joint Repairs

As the loss of mortar joint material was the underlying cause of the stone failure, the project undertook the complete repointing of all stone joints and the addition of discrete metal weathercaps to improve the sealing of mortar joints exposed to weather in the horizontal plane.

Portico Soffit Repairs

The investigation phase of the project observed failures and cracking in the plastered dentils in the soffits of the Gallier Hall portico. The cause of failure was identified as the corrosion of ferrous metal anchors caused by the 20th century application of non-breathable coatings.

A pinning repair using thin anchors in both horizontal and vertical axis applications was developed to stabilize the underlying brick structure of the dentils. The offending coatings were removed and replaced with a lime wash coating that will allow proper breathing of the historic soffit materials.

A historic surface analysis was performed to match the color of the lime wash to the original historic colors used. As the loss of mortar joint material was the underlying cause of the stone failure, the project undertook the complete repointing of all stone joints and the addition of discrete metal weathercaps to improve the sealing of mortar joints exposed to weather in the horizontal plane.

Material Reuse

The process of installing the masonry anchor system generated a large quantity of removed material in the form of cylindrical marble cores.

Measuring 1-3/4” in diameter, these objects presented an opportunity to create new objects from the historic ma- terial fragments of this iconic building.

Upon removal from the façade, the marble cores were salvaged and will be sawn into thin wafer shaped pieces. These pieces will then be polished and used to create a line of jewelry that will be sold to the public to assist in funding future phases of interior restoration work at Gallier Hall.

Construction Coordination

Scaffolding of the entire façade was required to adequately reach all areas of the facade requiring work. In order to meet the expedited schedule, lighting was installed on the scaffolding to facilitate work beyond daylight hours. As areas of the facade were completed, the design team accepted the work and scaffolding could be removed from these upper areas while work continued below.

The project location along active streetcar lines in New Orleans’ Central Business District necessitated numerous after hours operations, including the 3:00 am placement by crane of the replacement marble cornice stone.

Construction Coordination

Early morning installation of replacement stone block.

Completion

Upon substantial completion in late December 2015, the project restored the striking whiteness of the marble façade and repaired all damage from the stone failure. The jobsite was immediately turned over to the City’s work crews to begin preparation for the Carnival festivities which were due to begin in January 2016.

Carnival 2016

Thanks to the efforts of the owner, contractor, and design team, the project was delivered on time and the Carnival celebrations were returned to their traditional location at the Gallier Hall portico. In this image, the mayor of New Orleans and Rex, the king of Carnival share a toast on Mardi Gras day, Tuesday, February 9, 2016.