2.5mm X, 0.5mm Y

Uh oh.

That’s a non-negligible amount of movement since the crack monitor was installed. The surface itself is gypsum board – the thin filaments visible at the crack are joint tape – but the movement is structural, imposed from outside and made visible by the brittle finishes.

This type of crack monitor is as low-tech as it can be: it’s two piece of plastic glued to the surface, one on each side of the crack, photographed once per week. They are amazingly effective at tracking long-term movements across cracks, which are usually indicative of structural damage to a building.

Our work is often quite low-tech. Yes, we use very nice computers to make pretty models of structures, but much of the time we are observing large objects move relatively large distances. The interest is in the interpretation, not the tools.