How do you analyze a wall crack from cause to effect?
Thursday, July 2, 2020
Understanding what the different wall crack patterns mean can often point you directly to the underlying cause. Each type—inverted “V,” stairstep, vertical, etc—indicates a likely scenario. This way of evaluating a structural problem in a wall is essentially going from “effect to cause." But sometimes the answer isn’t that clear-cut. There may be multiple or hidden causes and you need to dig deeper, working backwards from "cause to effect."
Here’s a list of things to check to do a more thorough analysis:
1) What is the wall really made of? Concrete block walls are sometimes finished with siding and, conversely, a stucco finish does not automatically mean the wall is block. It could be wood stud frame, or part block and part wood stud frame. A brick wall could be structural brick or brick facing over wood stud frame. See our article How can I tell if the exterior walls of a house are concrete block (CBS) or wood or brick? for more on this.
2) What is the history of the wall? How old is it? Was there a previous structural problem? When was it repaired? The new crack could be a long-standing problem that was only costmetically fixed.
3) What is the history of the area around the wall? Was there a nearby roof leak, plumbing leak, tree removal, or excavation? We suggest reading What should I do about a tree with roots running under my house?
4) Are there cracks on other walls or ceilings of the home? How does their geometry relate to the one in question?
5) How does the thickness of the crack vary? Is it wider at the top or bottom? Thinner at the same point on the inside or outside?
6) Any recent severe weather? Heavy rains, severe cold, windstorms.
Combining the answers to these questions with your interpretation of the crack geometry will give you a better idea of what’s going on.
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