SOCOTEC Monitoring Supports SPAB with the Conservation of Grade II* Listed Chapel

Working alongside The Society for the Protection of Ancient Buildings (SPAB), SOCOTEC Monitoring has been donating instrumentation and providing technical expertise to contribute to the monitoring aspect of the project.

Jeff Foggo, senior project manager for SOCOTEC Monitoring, originally discovered the project, having spotted works taking place on his daily commute. While it is one of the more unconventional projects that SOCOTEC Monitoring has undertaken, key learnings from previous monitoring services for larger scale heritage buildings and historical assets have been applied to the Old House Project to ensure that the building is structurally safe during periods of extensive repairs and that its integrity is maintained.  

Derelict for approximately 50 years, SPAB’s five-year ‘Old House Project’ will repair and conserve the former chapel, with the overall aim of turning it into a domestic property for sale. The interesting historical nature of the building has garnered attention from Historic England, Kent Archaeological Society, MOD and the local council, who, alongside SOCOTEC Monitoring and a raft of volunteers (including structural engineering organisations, archaeological societies, local roofing and fencing contractors) have assisted SPAB in their efforts to bring St. Andrews back into use.

Structural Preservation

With conservation of the structure a key priority, SOCOTEC Monitoring used low impact methods to install automated tiltmeters on the external west and south walls in conjunction with the SPAB’s Passive temporary shoring. The purpose of the tiltmeters was to measure live and continuous change in the rotation and movement of the walls of the structure as repair works progressed. By attaching the tiltmeters using a non-corrosive adhesive, damage to the natural stonework would be prevented, further contributing to the preservation of the structure.

SOCOTEC Monitoring recommended that the frequency be read every three hours to collect sufficient data and preserve battery life, which was then changed to hourly once members of the team were frequently on site. This data is being manually collected from each tiltmeter at regular intervals, before being logged and reported. The tiltmeters have been set up with predetermined movement trigger values and, in the event of a trigger value being breached, email notifications will be sent to designated personnel for action to be taken. The alert received will provide details of the trigger location and the magnitude of the alert, showing a value and the trigger status of amber, red or black to immediately indicate the severity of the movement.

The St. Andrews project was carried out during a working party which comprised many on-site volunteers, conservation specialists and camera crews, whose aim was to study the conservation project and make recommendations based on its findings. While COVID-19 may have hampered this, they were able to capture footage of SOCOTEC Monitoring installing the tiltmeters.

Monitoring the impact

In addition to the tiltmeters, SOCOTEC Monitoring installed 3D manual survey targets on all external walls across 24 separate locations around the building. At some locations, only one target has been installed due to the shorter height of the walls, but in others – where the walls are higher – arrays of two targets have been installed to allow a profile of these walls to be measured. Stable reference points were established by using permanent structures in the surrounding area, over 30m from the site boundary and outside the zone of influence. The client required a straightforward solution to automate the readings of tilt-meters moving forward, which were currently manual.  

SOCOTEC Monitoring is carrying out monthly surveys of these targets on behalf of SPAB to gain a greater understanding of the impact of vegetation clearance, heavy rainfall and seasonal and construction-related movements. All of the data for the project is being presented via SOCOTEC Monitoring’s own visualisation platform, Calyx OMS, which the client, stakeholders, designers, structural and civil engineers all have direct access to.

* Please see below a selection of diagrams detailing SOCOTEC Monitoring’s installation of tiltmeters and prisms at St. Andrews, which were obtained using Calyx OMS.

Acoustic/vibratory monitoring and site investigation works

SOCOTEC’s team of acoustic consultants were invited to participate in the St. Andrew’s project from a preliminary stage, having been involved in early meetings all the way through to the Royal Institute of British Architects (RIBA) Stage 2. The purpose of these meetings was to provide technical assistance to the architects, Malcolm Fryer Architects working on the project in line with BS8233:2014 (guidance on sound insulation and noise reduction for buildings), with a particular emphasis on conducting noise modelling.

Due to the site’s proximity to the M20, the level of road traffic noise posed a concern for re-establishing the dwelling use. As a result, a 3m high wall with a 1.5m wide roof was modelled in order to create a covered walkway where noise from the motorway was greatly reduced.

In addition, SOCOTEC’s Ground Investigation team has also played its own part in the project, having visited St. Andrews to carry out a walkover survey. The findings of this visit were presented in a report which provides an overview of the site and potential ground conditions, addressing the geotechnical risks to the project. The report includes a ground investigation proposal which would determine possible causes of structural distress and the ground water conditions in relation to the potential underpinning of the chapel building, while also considering suitable foundations for a possible new building at the site.  

Making a difference

“Having provided monitoring systems for other historical buildings and assets, the team at SOCOTEC Monitoring is familiar with many of the unique challenges faced when working on heritage sites, so I knew it was something we could support SPAB with,” commented Jeff Foggo. “When recommending a suitable monitoring system, every care was taken to ensure installation methods caused as little impact to the listed building as possible, being mindful of the preservation of the retained structure.”

Jeff continues: “Being a non-profit making project, SOCOTEC Monitoring kindly donated the instrumentation, and I will be manually collecting the readings on my journey home. It’s a really interesting project to be involved with, and I’m looking forward to seeing how the repair works progress.”

If you have a geotechnical or structural monitoring challenge to discuss, please get in touch with us on 0845 203 2112 or email salesuk@socotec.com.