Foundation Cracks: Big Problem or Common Occurence?

Courtesy of Rob Wetterstroem with American Verified Home Inspectors:

When most buyers have an inspection done, their biggest priority is to ensure there are no catastrophic defects with the house.  By catastrophic they usually mean no issues that are going to be terribly expensive to fix, that make the house unsafe, or will prevent them from selling the house at some point in the future.

From an expense and resale standpoint, foundation issues are at the top of the list.  While you probably aren't looking to become an expert on structural issues, a few basic pointers regarding foundation cracks can help you educate your buyers and sellers, and help allay any unnecessary fears that arise during or after the inspection. 

For starters, everyone should know that all concrete cracks eventually. If you look at your driveway, garage slab or front walks, you'll see settlement cracks.  Cracking is not unusual, but displacement of foundation walls, whether block or poured concrete, can indicate indicate a problem.

For this article we'll stick with identifying cracks in the foundation walls of a home; what is common, what is considered significant movement, and what to do if you suspect there are serious foundation problems.

Most homes settle within the first five to ten years of being built. The ground beneath the home will settle into place, and the concrete foundation goes with it.  Signs of this are vertical, diagonal or horizontal cracks.  In poured concrete foundations, vertical cracks are more common.  When you see a crack, looking at the width gives you an indication of the amount of movement.  Typically if a crack is wider than a 1/4th of an inch, the movement is considered significant.  If it is less than 1/4th of an inch, it might not be considered significant, but worth having the crack sealed, and monitor in the future for further movement.

Horizontal cracks are more likely to be found in block foundation walls.  Typically these cracks are three or four courses of block below the ground, because this is where the frost line is. The ground expands and contracts with the elements, i.e.  Excessive rainwater causes clay soils to expand, which puts pressure on the foundation walls, enough of which can cause movement.

In the winter, frozen soil expands and does the same thing (hence the reason you see the cracking at the frost line). These forces can cause the wall to bow inward towards the basement or crawlspace.  When a block foundation wall is laid, the wall is perpendicular to the floor. If it is being displaced due to excessive force, the wall will bow or sweep inward, causing a hump in the wall. Sometimes this movement is clearly visible, and other times it's not.  By using a level, you can determine how much the wall has moved.  There are times you will see a horizontal crack from one end of the wall to the other, but no negligible amount of movement.  If the wall has been displaced an inch or more, this would be considered significant, and further evaluation by a professional engineer is recommended.

It's interesting to note that a foundation wall is not considered in a state of failure until it moves past its center of gravity. Typical foundation walls are 8 inches thick, so for it to move past its center of gravity, it would have to move approximately 2.66 inches (1/3rd of 8 inches) to be in a state of failure.

If there is an inch worth of movement, while the wall is not at a state of failure yet, evaluation and repair work will likely be needed.  Calling a professional engineer is what should be done next. Some folks make the mistake of calling a foundation contractor straight away, skipping the engineer's evaluation.  This can be costly.

There are many qualified and honest foundation contractors out there, but it's the engineer who has been trained to properly diagnose the problem, figure out what's causing the movement to take place, and to create detailed specifications on the proper repair. With the engineer's drawings you can then find contractors to bid on the project.

Working off one set of plans, your bids should be comparing apples to apples, not four different repair proposals, and four wildly different prices for them all.  For some reason, people want to save the few hundred dollars for an engineer's evaluation and drawings, and put that money towards repairs.

I assure you, more often than not, using an engineer's services will be money well spent. It saves you more money and headaches in the long run, and will ensure that the problem has been properly addressed.  Most of the time cracking and settlement of a foundation wall is within tolerable limits and there are no adverse affects to a home's structural integrity.

If a foundation has been repaired with the help of a professional engineer and using licensed and qualified foundation contractors, resale value should not be diminished down the road.

If you have any questions regarding this topic, or other inspection related issues, feel free to visit American Verified Home Inspection's Homepage or please call Rob Wetterstroem at 513.226-1217.  He can also be reached through email at RWetterstroem@Yahoo.com.