Consecrated in 1959, the Cathedral of Mary Our Queen is a vibrant historical landmark in the City of Baltimore.
Worker removing the original mortar
The team had to be extremely careful not to damage the limestone exterior with the diamond blade grinders used to extract the mortar
The new mortar was mixed to match the original color.
Repointing of new mortar to the joints
Project Team 
STRUCTURAL
Specialty Contractor

Cathedral of Mary Our Queen

Project Description 

Consecrated in 1959, the Cathedral of Mary Our Queen is a vibrant historical landmark in the City of Baltimore. Constructed with a brick and terra cotta core and an interior and exterior facing of Indiana limestone, the Cathedral is 373 feet long (41 feet longer than Saint Patrick's Cathedral in New York City) and reaches 163 feet to the top of the spires. With mortar joints falling out of the walls of the two bell towers and a large displaced stone hanging 60 feet in the air, the need for repairs was evident. The Archdiocese of Baltimore had worked with STRUCTURAL on several other historic repair projects and recommended them for this job.

To aid in inspection, STRUCTURAL's  project development team rappelled the 150-foot towers and used a video camera to document the existing conditions of the mortar joints for up-close investigation. STRUCTURAL discovered vertical cracks that followed the mortar joints and even went directly through the limestone in some circumstances. The exterior assessment started with the dislodged stone, which STRUCTURAL removed and reset. While the stone was an isolated issue, an inspection of the remainder of the sanctuary dictated a need for a 5-year program to re-point the entire building.

The most immediate repairs were needed in the north and south bell towers, both of which would require 100 percent re-pointing-an area of nearly 17,500 linear feet. Compositional testing was performed on the existing mortar to determine its strength and to ensure a color match with the repair materials. A pre-blended pointing mortar that could be applied in one lift was custom-designed and -colored for the cathedral.

Nearly 1,072 linear feet of cracks were sealed for both towers using a small amount of sealant applied directly over the crack in an effort to make the repair completely reversible yet minimize water infiltration. The coping stone cross joints of both towers were resealed using a premium-grade sealant, followed by a new weather lead cap to elongate the life expectancy and durability of the sealant.

During the repair process, the team had to be extremely careful not to damage the limestone exterior with the diamond blade grinders used to extract the mortar. Access presented another challenge: The only way to access the towers was via ladder, which required a precise mobilization strategy to ensure all the materials needed were available. In addition, because the towers were located at the main entrance of the church, work often needed to stop quickly and unexpectedly to accommodate the needs of the parish. STRUCTURAL took several important safety steps to ensure that pedestrians would be protected and closed off their access to the site. The Archdiocese and the Cathedral were extremely pleased with the results of this phase of the project, and STRUCTURAL is currently monitoring the repairs while developing the next phase of preservation work.