Dear My Foundation Guy,
My home is on the market and the buyers are requesting that I have someone evaluate the foundation for possible structural damage. How do I know if there's structural damage or if the cracks in my foundation are no big deal?
~excerpt from email inquiry from seller courtesy of Jack McGuire, Peak Structural
Cracking in concrete is a natural phenomenon because it is strong in compression, but very weak in tension. When a concrete foundation wall encounters stress forces from outside elements like expansive soil, the portions of the wall that are experiencing tension will crack. Some of the forces that can act against your foundation on a regular basis include: seasonal temperature changes, seasonal soil swelling and shrinking due to weather and watering, and changes to grading due to landscaping or soil erosion over time. Occasionally, the addition or removal of plants, shrubs, or trees can also affect your concrete foundation.
Most residential foundation walls are designed to withstand the forces present in standard/normal soil conditions. In some cases, foundation walls have been reinforced, or otherwise altered due to high ground water or soil concerns. You will usually see cracking occur in three ways: vertically, horizontally, or diagonally from a stress concentration.
Just because a wall has cracked doesn’t mean that it has failed as long as the crack is small and unchanging. If the crack is 1/8 inch or less, is nearly vertical, has no lateral separation (spreading), is not very deep, and does not have moisture present, then it should be monitored, but action is not usually required. This type of crack is a shrinkage crack and occurs as moisture in the wall evaporates, causing the concrete to shrink into voids created by the escaping water.
Horizontal cracks require more attention. A horizontal crack is concrete’s way of ripping or splitting due to excess tension in that area. According to Residential Concrete Magazine, all horizontal cracking should be checked out by foundation repair industry professional as soon as possible because these cracks tend to grow rapidly.
You may notice cracks spreading out from a corner diagonally. Whenever concrete forms a sharp angle, there is a stress concentration that almost always results in tiny, surface crack. These cracks are called “reentrant cracks”. If these cracks deepen, thicken, or grow, it is time to consult an expert about reinforcing the area since the stress concentration is breaking down the concrete.
There is one type of crack that is always a concern: tapered cracks. If a crack is larger at one end, it indicates shifting and other movement in the foundation . If you’d like more information about tapered cracks, please visit our website by clicking here.
The easiest way to figure out if the cracks are real issues or natural cracking is to have a Structural Evaluator take a look at the property. Virtually every reputable foundation repair company in Denver will offer you a FREE estimate. Once the evaluator determines if there is damage or not, you will know whether or not to get an engineer involved. Using the free estimate to determine damage will save you money in the long term.
~Reply from Aaron Henes, General Manager, Peak Structural located in Lakewood, CO 80228