St. Paul Cathedral Project
In 1904, John Ireland, Archbishop of the Diocese of St. Paul, Minnesota, began plans to create a great cathedral to serve the growing community of St. Paul. Ireland secured land on what was known as St. Anthony Hill and named Emmanuel Louis Masqueray the architect. Built in the Classical Renaissance style of architecture, the Cathedral was adapted from the original plan of St. Peter's in Rome, but the floor plan was in the shape of a Greek cross. The cornerstone was laid on June 2, 1907, and the structure, still incomplete, was dedicated April 11, 1915.
In 2000, Harry J. Flynn, the Archbishop of the Diocese of St. Paul and Minneapolis, sanctioned a two-year, $35 million restoration project, including reroofing the great dome and all the roof areas. The design team consisted of McGough Construction, general contractor, Miller Dunwiddie Associates, the preservation architect, and Roof Spec, Inc., the consultant.
The roofing contractors, consisting of Dalco Roofing and Sheet Metal, Inc., of Plymouth, Minnesota and John A. Dalsin & Son, Inc., of Minneapolis, Minnesota removed the architectural copper sections for restorations and repairs. Many of the architectural copper elements adorning the roof were originally unsupported, stamped hollow copper. As new and refurbished copper elements were replaced where possible, they were given a solid substrate of wood blocking. The previously unsupported decorative copper, which was also predominantly stamped hollow, was filled with spray-applied polyurethane foam to provide support and to minimize condensation.
Much of the dome's exterior skin consisted of interlocking copper panels. But as the interlocking sections approached the base of the lantern, the copper changed into a Bermuda-style panel. 
With the dome nearing completion, the scaffolding was adjusted so work could focus on the lantern. Initial repairs to the lantern's base had to be reworked after shearing and tearing of the new copper were discovered as a result of wind loads and the scaffolding's extreme weight.
At the same time that work was being completed on the uppermost lantern and cross section, the two lower bell towers were being repaired and refurbished and the transept gable roof areas re-roofed. The transept roofs received the same substrate preparation as the dome. However, due to the massive size of the bell towers and the fact that they were predominantly ornamental and not necessarily requiring waterproofing, these were simply repaired in place with new copper being attached to the existing framework.
Now completed, the restoration has provided renewed appreciation for the vision and efforts of St. Paul's first Roman Catholic Archbishop, John Ireland, and for the legacy he left all who visit St. Paul's Cathedral in Minnesota's capital city.
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