The completion of the Trinity Dome at the Basilica of the National Shrine of the Immaculate Conception was the final major piece to finish the construction of America’s largest church, whose construction started in the 1920s. The Trinity Dome is elevated 159’ above the finished floor and was the last one among six other domes to be decorated with Venetian glass mosaic and stone.
The crucial part of this project was the engineering of a platform that supports the scaffolding and protects the public underneath it – as the church was to open throughout the entire construction period, including large televised Sunday masses.
One of the most challenging aspects of the project was to develop and execute a steel erection and rigging procedure to build massive columns, beams, and trusses inside a church without the assistance of a crane.
The creation of an innovative material transportation system allowed us to transport 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 carry them through the narrow door opening and inside in the picking position, ready for lifting.
It was an incredible engineering achievement, which displaced the Owner for only one weekend of church services over two years, as our 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 design scaffold system along with two-person material hoists: one to the platform and the second to access the upper levels of the dome. The entire scaffold structure was then enclosed to protect the visitors from construction dust or 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, as we had to ensure it matched the exact curvature of the original gypsum plaster substrate.
The mosaic installation took six months of continuous work. The 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 system finished six weeks ahead of schedule, and the mosaic was dedicated on schedule, December 8th, 2017.
Overall, this project consisted of structural steel, concrete, highly complex rigging, and engineering in an Owner-occupied space. The platform and scaffold systems were 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.
The mosaic was incredibly well received by the Owner and the pilgrims who visit the Shrine. This project is a once in a century opportunity and deserves recognition for the superb level of quality in the ancient art of glass mosaic. It was the 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: 21,000 sqft of mosaic
Services: Rugo served as the GC and self performed steel erection, dismantle, furnish and installed all plaster, mosaic, and stone work