St. Francis de Sales Church

Philadelphia, PA

Completed in 1911, St. Francis de Sales Church was designed in a Byzantine Revival style by Henry D. Dagit with a massive structural tile dome and roof vaults designed and built by the Guastavino Fireproof Construction Company. The cross-shaped plan consists of a large, domes central space with shallow transepts to the east and west of the crossing. The exterior walls are clad in rock-faced white marble with decorative elements executed in Indiana limestone. At the crossing, brick walls form an octagonal base for the terra cotta and brick drum and polychrome glazed-tile dome. The interior is richly decorated with marble, granite, limestone, patterned brick, and polychrome terra cotta. The central dome, with a glazed oculus, is of Guastavino tile with a diameter of approximately 60 feet.

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  • Document existing conditions at the interior and exterior, including the Guastavino tile dome and vaults, in order to assist the project team with the development of a renovation plan.
  • Investigate subsurface drains and pipes.
  • Assist Historic Building Architects with a feasibility study and design of a future access system.


  • Used a combination of  industrial rope access on the exterior and an aerial lift at the interior to gain hands-on access to the structure.
  • Provided live-feed video to the project team during inspection of representative exterior areas.
  • Sounded Guastavino tile and masonry materials at the interior to identify subsurface conditions.
  • Used a See Snake fiber optic diagnostic tool to investigate roof drains and leaders.
  • Opened probes in exterior masonry to characterize subsurface conditions.
  • Documented and measured existing conditions at interior drum to assist with planning for a future access system.
  • Performed anchor pull tests as part of fall protection system design.

building owner

  • Archdiocese of Philadelphia

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