Finding a crack in your basement wall can be alarming, but often the problem is only cosmetic. Learning about the different types of cracks and their causes can help guide you to the right repair option.
Types of Cracks
Cracks come in four common forms based on the orientation of the crack — vertical, diagonal, stair-step, and horizontal. Vertical and diagonal cracks are the most common type to affect the average basement. The cracks can form anywhere on the wall, although stress points are often the location of the damage. These include areas where two walls meet, where the wall meets the basement floor, and in corners. Cracks can also form at the edges of any windows or where the wall is penetrated by something, such as a floor joist bolt.
A common cause of cracking is at locations known as cold joints. These are where two layers of concrete meet, whether it's at a corner junction or simply one layer of concrete placed over the top of another. When the layers of concrete dry at different rates, one layer may crack. Cracks can also form from concrete shrinkage as it dries, but these types of cracks are more common on newer homes. Of course, settling and foundation damage can also result in cracking.
When to Worry
Horizontal and stair-step cracks are the greatest concern, as unlike vertical and diagonal cracks, horizontal typically means there is some sort of structural damage present. Soil movement under or around the basement that leads to uneven settling of the home is one common cause, as is improper backfilling against the walls of a new basement foundation. Water pressure in the soil, soil movement, and improper mixing of the concrete are also possible issues. Stair-step cracking occurs on cement block basement foundations, and the causes are similar to horizontal cracking. Horizontal and stair-step cracks require major foundation repair as opposed to simple crack filling.
For minor cracks and cosmetic cracks, the only repair needed is to patch the damage so that the wall looks better and the crack doesn't become larger. For deeper cracks, your repair technician may inject a polymer-based crack filler into the crack. The polymer makes the patch somewhat elastic, which prevents further cracking from occurring. For superficial cracks, a polymer patching compound may be simply painted over the surface. You can then paint or cover the walls so that the patch repair isn't visible.
Contact a basement wall crack repair service for more help.