Structural monitoring of a church subject to cracks: understand before acting

Faced with this uncertainty, a monitoring mission was entrusted to the company SID, with the objective of assessing the situation and obtaining tangible elements to decide on possible interventions.

Mission objective: to measure crack activity over time

The core of the mission was based on a simple problem: observing the evolution of cracks over time in order to determine whether they were active or not. The interest of this approach is twofold: to avoid unnecessary work in the event of proven stability, or on the contrary, to plan corrective actions if the activity is confirmed.

SID has thus deployed lightweight instrumentation adapted to the heritage context of the church, with particular attention paid to the non-intrusiveness of the solution and the readability of the results.

Fast, precise and cable-free instrumentation

To meet the site requirements, two types of sensors were installed:

• DELTA L+: connected crack opening measurement sensor with long-range transmission.
• DELTA L: additional manual crack sensor, for redundancy on certain critical axes.

The sensors were mounted using a lightweight drilling system designed to minimize impact on historic materials. Commissioning was completed in less than a day. Once installed, the sensors began transmitting data continuously, without the need for on-site intervention.

The measurements allow for precise tracking of movement patterns, while correlating them with temperature data. This cross-analysis is essential for distinguishing thermal effects from actual structural movements.

Results and benefits

The first months of observation revealed moderate crack behavior, with variations primarily correlated with seasonal effects. Thanks to access to the data via the Feelbat platform, SID engineers were able to establish a reasoned diagnosis, ruling out the hypothesis of a rapid or dangerous phenomenon.

This type of monitoring gives project owners the opportunity to postpone certain major operations, while maintaining the ability to monitor and react quickly in the event of unforeseen developments.

For Meril Archinard, manager of SID: "Understanding is essential to act appropriately, whether through additional studies or to confirm the causes already identified. This is a key step in ensuring both the safety of people and the sustainability of the investments made in repairs."