ADP Architects at APTI: Restoring the Great Dome at St. Bart’s Episcopal Church
June 17, 2025
ADP Architects led the restoration the Great Dome at St. Bartholomew’s Church on Park Avenue. This involved the recreation and installation of 6,300 individually cut and glazed terra-cotta tiles over the eight panels on the dome.
Drew Hartley, AIA, Principal of ADP Architects, was invited to speak on intricacies and complexities of the Great Dome’s legendary restoration, which earned a 2018 Lucy G. Moses Preservation Award. His presentation was part of the Association for Preservation Technology International’s (APTI) 2025 Annual Conference in Providence, Rhode Island, which celebrated the tenets of Traditional Craftsmanship in a Technical World.
Project Facts:
Sector: Sacred, Cultural
Location: New York, NY
Scope: Architectural Design and Planning; Historic Preservation
Project Type: Historic Restoration
Status: Completed
The Great Dome was the first of many architectural restoration projects currently underway at St. Bart’s Episcopal Church, a testament to the benefits of engaging a preservation architect with 40 years of technical knowledge to orchestrate the careful planning and project phasing essential to successfully saving historically significant buildings in Manhattan.
An initial assessment of the Great Dome at St. Bart’s revealed significant water infiltration, resulting in stone deterioration, irreversible flaking and bio-growth on the surface of the dome, gutters and at mortar joints.
The existing cladding, which was deteriorated beyond repair, involved a blend of marble, terra-cotta and granite tiles. Through a series of tests and probes, it was determined that repairing the dome with a unified materiality—terra-cotta—would ensure the dome’s longevity and ease of maintenance for decades to come.
The unmistakeable craftsmanship of the Great Dome’s restoration is evident from the analog rubbing of the stone panels to the careful application of additional waterproofing layers that kept the spirit of the dome’s Guastavino construction alive.
A structural feat was undertaken by the scaffolding team to create a scheme that carefully removed the heavy external limestone ribs and used the weight of the dome itself to support the scaffolding system for restoration—eliminating the need for shoring inside the attic of the dome.
See this link for a quick, step-by-step animation of how the Great Dome was restored.
The 28th Lucy G. Moses Preservation Awards Ceremony was held at St. Bart’s Episcopal Church—known in its heyday as the “Jewel of Park Avenue.” St. Bart’s Episcopal Church was declared a New York City Landmark by the New York Landmarks Preservation Commission in 1967, listed on the National Register of Historic Places in 1980, and was designated a National Historic Landmark in 2016.
Above: The Completed Dome Restoration
Below: Restoration In-Process
