Failure Portrait: The Corner

by Don Friedman on March 22, 2016

Can you tell the difference between a break and an architectural feature? What if the failure planes of the stone are so clean that they pretty much match the finished surfaces elsewhere?

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There’s no embedded metal. The cracks that led to that corner piece falling off and the cracks in the main water-table stone above are probably the result of combined thermal movement and restraint. In other words, the outside corner of the water-table will change temperature faster and more thoroughly than the field of the wall because of its exposure on two adjoining faces, top, and bottom. Meanwhile the stone can’t move very much became it’s locked in place by the weight of masonry above. We often refer to this kind of scenario as the building making its own expansion joints: the cracks nicely define where the differential movement is taking place.

Meanwhile, who knows where the missing stone corner is.

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