Cracks Or Crisis: How To Know If Your Foundation Is In Trouble

It's not an uncommon occurrence for a homeowner to discover a crack or two in the home's concrete foundation and then immediately panic. Is the structure compromised? Is the whole house going to collapse?  Fortunately, the answer is usually no. Most foundation cracks are normal and won't affect the structural integrity of the home. But how can you tell the difference between cracks that can be ignored and cracks that need immediate attention? Here are a few characteristics to look for to help determine if your concrete foundation has normal cracking or problematic cracking.

Normal Cracks

A few cracks in a concrete foundation are usually nothing to worry about. Even a freshly cured foundation will have a few. The reason for this is that concrete shrinks as it cures. Concrete is a combination of an aggregate like gravel or sand plus water and cement. To keep concrete from moving too much and to ensure that it's structurally sound, builders will place metal rebar throughout the concrete. This is done to carry the tensile loads and to keep the shrinking process from warping the shape of the foundation. Because of this, even when there are small cracks, the integrity of the foundation typically isn't affected. These types of cracks aren't worth worrying about:

  • Meandering hairline shrinkage cracks on your basement floor, less than 1/16" wide and tapering at the end, often originating at a 90-degree offset corner.
  • Vertical hairline cracks on the foundation walls less than 1/16"
  • Hairline cracks in the mortar between bricks above the concrete foundation  

Problematic Cracks

There are several reasons why problematic cracks may occur on a concrete foundation. One possible explanation is that the soil wasn't properly prepared before the foundation was poured and the home has settled too much. As soil is exposed to water and air, it loses and gains moisture according to the weather, resulting in the expansion and contraction of the soil. This causes the home to settle or sink. Some settling is always expected but too much spells trouble. Other problems are caused by water penetration, resulting in the slow erosion of the concrete over time or the buildup of hydrostatic pressure. Another possible reason is that the concrete wasn't mixed properly. Any of these factors can result in problematic foundation cracks that require repair. Here are a few problematic cracks to watch out for that might require foundation repair:

  • Cracks wider than 1/4"
  • Horizontal cracks along the foundation walls, often the result of hydrostatic pressure caused by too much moisture.
  • Stair-stepped cracks through brick or brick mortar
  • Cracks in interior walls, especially over doors and windows.

For more information, contact a company like J & D Waterproofing.


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