Cracks in concrete blocks can be caused by flooding, droughts, heavy traffic nearby or by a home being located near a construction or industrial area or near mining areas.
Q: Our home is on a hillside and was built with a walkout basement. The walls are concrete blocks on all sides except the wall on the low side of the hill. That wall is 2-by-4 wood studs.
I have never had water in the basement, but I have noticed cracks along the front wall and at the corners of either side of the wall. The crack is about 2 feet from the top block and the cracks on the sides follow the mortar joints at an angle.
Should I be concerned with all the cracks? Should I have the basement repaired, or should I contact an engineer? Any advice would be appreciated.
A: Cracks in concrete blocks can be caused by flooding, droughts, heavy traffic nearby or by a home being located near a construction or industrial area or near mining areas.
Anytime you notice horizontal cracks in a foundation, you should be somewhat concerned. If it's just a hairline crack, that might be normal movement due to soil displacement.
If the crack is larger than an eighth of an inch wide, you should contact a structural engineer to evaluate the design and construction of the foundation and wall.
You should also take into account the location of the crack. A small crack 2 feet down on the front wall is more than likely caused by droughts.
I usually find this type of crack to be at the same level as the yard on the outside of the wall. As the soils outside shrink, the wall can and usually will crack.
A larger horizontal crack or a crack midway down the wall should be inspected by an engineer. The pressures of the soils or water are pushing the wall inward and the wall could fail.
The cracks on sidewalks are called "stair step" cracks and are caused by settlement of the footings under the wall. Again, this might be caused by shrinkage, but larger "stair step" cracks will need to be inspected.
You can monitor the cracks by marking the ends of each crack with a black marking pen and then add the date you made the mark. Over time, you can see if the crack is growing.
If you have a vertical crack in the wall it may be a larger issue. If the crack is wider at the top than at the bottom, then the foundation may be settling on one or both ends or it may be heaving in the middle. In either case, a vertical crack can be bad news and you need an engineer.
Dwight Barnett is a certified master inspector. Contact him at C. Dwight Barnett, Evansville Courier & Press, P.O. Box 268, Evansville, Ind. 47702 or firstname.lastname@example.org.