(CS1.1) Using structural health monitoring in historic religious sites with limited funding to guide and assess conservation efforts: a case study of the Cathedral of the Immaculate Conception

Historic places of faith contain vast open spaces, high vaulted ceilings, slender towers and spires, and intricate detailing—awe-inspiring elements that can become concerns for structural stability. As users, these places desire to remain open and focus their financial resources on their mission statements, rather than their buildings. These pose challenging conditions for building professionals conserving the site. The recent collapse of an 1850’s New London, Connecticut steeple and subsequent demolition of the church highlights a need to implement a monitoring system in these heritage buildings. The use of structural health monitoring (SHM) can provide early warning systems for structures at risk of failure and inform conservation for buildings with limited funding, allowing for more targeted conservation efforts that enable minimal changes to the historic fabric while confirming the success of interventions.
This presentation touches upon the unique considerations involved in conserving historic places of faith before delving into the use of SHM in these structures to inform and assess conservation. The discussion is placed into context through a case study of the Cathedral of the Immaculate Conception, Saint John, NB, covering the current state of the structure, sensor selection and implementation, planned conservation works, and an assessment of the emergency stabilization efforts. While the church serves a wide catchment area, this cathedral is located in a community with a child poverty rate of 23.1% according to the 2017 Statistics Canada census on children in low-income households. The Cathedral of the Immaculate Conception prioritizes financial resources used to serve the surrounding community and has a limited budget for building conservation. This is further complicated by interventions over the past 8 decades, introducing multiple concrete systems and steel structures inside the bell tower to reinforce the stone masonry walls and the spire’s central timber mast. Other areas of structural concern include cracking near the bell tower’s eastern pinnacles, cracking near a front façade pinnacle presently restrained by three metal bands, and moisture build-up in the interior bell tower. To ensure the most effective use of finances, a long-term SHM system is being implemented to inform and assess conservation efforts. Phase 1 of the sensor implementation, installed in December 2023, serves as an early warning system to assess the stability of the structure. Phase 2 is set to be installed in May 2024, monitoring additional areas with structural concerns while working towards a more comprehensive global understanding of the structure. Both phases will be used to monitor the emergency stabilization efforts taking place during spring and summer 2024, with the results of the conservation efforts discussed as a part of this presentation.