In August 2019 we reported on the installation of wall crack monitors at Slonim Synagogue, equipment used to detect structural movement and instability. We promised an update when the results of this survey were available.
While cracks are common in old buildings it is important for us to know whether they are recent or as a result of slow movement over the years. If there is only a very slow movement then structural stabilisation becomes less urgent. If there is significant ongoing movement then there is a possibility of a collapse which could damage the vaulted ceiling which would be difficult to repair and the wall paintings which may be impossible to replace. Repairs to the walls would be relatively simple.
Our objective when installing the crack monitors last year was to assess whether there is significant ongoing movement in the main walls to the synagogue. Since then readings have been taken over the course of a year and we now have some results to report. It's mostly good news – there is no need to undertake immediate stabilisation. Only two of the eight devices showed any movement, one of which was 0.8 mm and the other 1.0 mm. The maximum movement occurred over the autumn/winter period. The movement is a continuation of an existing defect, however it is so small that it is difficult to identify the cause.
But movement over 0.3 mm is a cause for concern and at a later date a full scale geotechnical investigation should be commissioned. The Foundation will be able to undertake this work more effectively once it completes its purchase of the Synagogue.