The St. Patrick?s Cathedral Restoration Project involved a multifaceted nine year undertaking that included conservation, expansion, and systems upgrades for the cathedral campus, designed by James Renwick Jr., which opened in 1879. By 2005, the fabric had reached a serious state of disrepair, including failure of the stone and plaster and deterioration of the stained glass windows. The physical plant was outmoded and space allocation exceeded available resources.
The project encompassed conservation of all building surfaces from the tops of the spires down to the terraces, on both the exterior and interior. This included conservation of marble, roofing, metals, plaster, wood, Beton Coignet cast stone, and stained glass; replacement of outdated infrastructural systems; and upgrades to the life safety systems and landscaping. Construction was conducted while allowing the Cathedral to remain open for daily masses, welcoming the millions of visitors who pass through its doors every year.
The team conducted extensive forensic and archival analysis to determine the composition of the original interior paint and exterior stone mortar specified by Renwick. Scanning technology was used to create accurate digital drawings of the Cathedral to supplement the original drawings., BIM 360 Field allowed the team to track and communicate via i-pads, in real-time, the status-changes of over 30,000 individual repairs.
Exterior stone was cleaned using the Rotec system, a micro-abrasive technology of low-pressure water, air, and crushed glass. Copper staining was removed with a clay poultice which drew impurities from the stone. On the interior, the team used multiple applications of Arte Mundit, a chemical cleaning latex peel. The new mist fire suppression system enables fires to be suppressed in the nave attic with 1/10 the water of a conventional sprinkler system. The ten-well open loop geothermal system will generate 240 tons of air conditioning and heat the Cathedral campus.