Two-axis crack monitoring (opening + shear)

What is 2-axis crack monitoring?

A crack does not always simply open. When the two parts of the structure move relative to each other within the plane of the wall, the movement breaks down into two components: opening, which moves the edges apart, and shear, which makes them slide parallel to each other. 2-axis monitoring measures these two components separately, with a single instrument.

How to recognise 2-axis movement?

Several signs should raise concern: crack edges that no longer line up, a visible shift between two masonry elements on either side of the crack, a stepped pattern following the joints, or a crack that changes direction along its length.

In these situations, a single-axis crack monitor is not enough. Installed perpendicular to the crack, it records only the opening and ignores the sliding: the measurement is not wrong, it is incomplete.

Which instrument should you choose?

Mechanical monitoring

The G6 gauge features two perpendicular verniers and is read by eye, with no power supply or maintenance. Resolution of 0.1 mm on each axis. It is the reference solution for regular monitoring of an accessible point.

Digital monitoring

The E1 gauge, used with its P2E1 plates, measures down to a hundredth of a millimetre. As the device is removable, a single instrument can monitor dozens of points on the same site: only the plates remain in place. It is the expert’s tool for instrumenting several cracks.

Remote monitoring

The 2-axis remote crack monitoring kit combines two R1 gauges and a shear kit. Measurements are transmitted automatically, with no site visit required, and an alert is sent as soon as a displacement threshold is exceeded. It is the obvious choice when the point is difficult to access or when monitoring must be continuous.

What if the movement goes beyond the plane of the wall?

When the two parts shift in depth, with one moving in front of the other, this is no longer shear but misalignment. If all three components are involved, 3-axis monitoring is required.

If you are unsure which type of movement to monitor, the selection guide by type of crack will help you decide.