The completion of the Trinity Dome at the Basilica of the National Shrine of the Immaculate Conception was the final major piece needed to finish the construction of America’s largest church, which had started in the 1920s.
The Trinity Dome is elevated 159′ above the finished floor and is the last one among six other domes decorated with Venetian glass mosaic and stone.
The crucial part of this project was the engineering of a platform to support the scaffolding and protect the public underneath it – as the church was to be open to the public during construction, including during large televised Sunday masses.
One of the most challenging aspects of this project was the development and execution of a steel erection and rigging procedure to hoist massive columns, beams, and trusses inside a church without the assistance of a crane. The creation of an innovative material transportation system allowed the transport of hefty loads with no impact to the floor or assistance of overhead lifting. Rugo designed special steel sleds to accept the massive steel pieces outside and gently transport them through the narrow door opening and inside in the picking position, ready for lifting.
It was an incredible engineering achievement, which only displaced the Owner for one weekend for their church services over two years. Rugo’s skilled labor crews worked around the clock for four weeks to minimize the disruption of the church services.
Once the platform was complete, we built a custom-designed scaffold system along with two-manpower material hoists: one to the platform and the 2nd to access the upper levels of the dome. This entire scaffold structure was enclosed to protect visitors from construction dust and debris.
Our team carefully removed 20,000 sqft of original gypsum plaster to expose the Gustavino tile substructure. The new plaster installation was a critical point of this project as we needed to ensure it matched the exact curvature of the original gypsum plaster substrate.
Once the plaster had cured, it was ready to receive the mosaic, the installation of which took six months of continuous work. The mosaic material was produced and assembled in Italy in half the initially estimated time.
The four large brick arches were clad with a custom end-matched series of Roman travertine, mounted on custom aluminum honeycomb panels; all mounted to a secondary aluminum framing system.
The dismantling of the scaffold and platform was completed six weeks ahead of schedule. The mosaic work was completed and dedicated on schedule on December 8, 2017.
This totality of this project included structural steel, concrete, highly complex rigging, and engineering in an Owner-occupied space. The platform and scaffold systems were specially designed to allow access for the installation of 20,000 sqft of new Venetian glass mural mosaic, and 8,000 sqft of new Roman travertine cladding.
This project is a once in a century opportunity, and it is deserving of recognition for the superb level of quality in the ancient art of glass mosaic. The mosaic has been applauded by the Owner and pilgrims who visit the Shrine. It was a Grand Prize Winner at the 2018 Coverings Convention.
Location: Washington, DC
Owner: Basilica of the National Shrine of the Immaculate Conception
Architect: Anthony J. Segreti, AIA
General Contractor: Rugo Stone LLC
Size: 12,000 sqft
Services: Rugo served as the GC and self performed steel erection, dismantle,