What You Need To Know About Corner Cracks

repairing corner cracks in slab-on-ground foundations

The bare minimum that you need to know

Corner cracks go by other names: wedge cracks and corner pops are two that come to mind.

Corner cracks are structurally benign. They more of a nuisance than anything else, but they are still a crack and can result in some buyers not moving forward to a 

What are corner cracks?

These cracks are always close to a corner of a slab foundation. A rectangular slab is likely to have four by the time the foundation is ten years old. Slab foundations of different shapes can have more depending on the shape and age of the slab.    

What the TREC SOP says about corner cracks

The TREC SOP says that the inspector must look for and report the presence of deficiencies in the beams. Corner cracks, in my opinion, meet the definition of a deficiency. There is no explicit requirement that inspectors recommend repair.    

What happens if they are not repaired?

Initially, nothing adverse happens. Some corner cracks will eventually come completely detached from the slab foundation. Some small fraction will eventually develop a very small vertical crack in the brick veneer directly above the one or more corner cracks. 

How should they be repaired?

The better question is: should they be repaired? In most cases, I would answer: no. The reason is simple. 

The easiest repair is injecting a caulk into the crack. This is a temporary, inexpensive repair. A longer lasting, more expensive repair would consist of removing the wedge and rebuilding the corner. 

A word of caution: a post-tensioned slab-on-ground is almost certainly an engineered product and as such, any changes to it must be under the direct supervision of the Structural Engineer of Record. Good luck with finding out who it was. In my experience, builders will not provide any information about the foundation design unless so ordered by a judge. 

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