Cracks in a Home Foundation

When most homebuyers have an inspection done, their biggest priority is to ensure there are no catastrophic defects with the house they are buying. By catastrophic they usually mean no issues that are going to be terribly expensive to fix, make the house unsafe to live in, or prevent them from selling it at some point in the future. Probably from an expense and resell standpoint, foundation issues would be at the top of that list.

While you probably aren?t looking to become an expert on foundation and concrete issues, a few basic pointers regarding this may help you to better educate your buyers and sellers to what they are looking at, and maybe help to allay any unnecessary fears that can arise during the buying/selling process. Knowledge is power, and the more you know, the more valuable you are to your clients.

For starters, everyone should know that all concrete is going to crack eventually. If you look at your driveway, garage slab or front walks, you will see settlement cracks. While cracking is not unusual, serious displacement of foundation walls, whether block or poured concrete, can indicate major foundation issues and some serious expense involved in correcting the problem. For this article we will stick with identifying cracks in the foundation walls of a home; what is typical, what is considered significant movement, and what to do if you suspect that the home has foundation problems.

Most homes will do its settling within the first five to ten years of being built. The ground beneath the footings of the home and the poured slab will settle into place, and the concrete foundation will go with it. Signs of this are vertical, diagonal or horizontal cracks. In poured concrete foundations, vertical and diagonal cracks are most common. Visually examining the foundation walls to locate cracks is the first step. When you see a crack, looking at the width gives you an indication of the amount of movement and seriousness of the situation. Typically if a vertical or diagonal crack were wider than a 1/4th of an inch, the movement would be 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. Typically 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). This causes 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, causing a hump in the wall. Sometimes this movement is clearly visible, and other times it is not. Taking a four-foot level, and putting the top of the level at the horizontal crack, you can determine how much the wall has been displaced. There are times you will see a horizontal crack from one end of the wall to the other, but the wall is still perpendicular to the floor, and there is a negligible amount of movement. However, if the wall has been displaced 1 inch or more, this would be considered significant and further evaluation by a professional engineer would be required.

It is 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 have moved approximately 2.66 inches (1/3rd of 8 inches) to be in a state of failure. If there is getting close to an inch of movement, while the wall has not moved into a state of failure, further evaluation is needed.

The next step is to call on a professional engineer to evaluate, and determine the proper repairs needed to keep the walls from further movement or having them brought back into their original position. Some folks make the mistake of calling a foundation contractor next, skipping the engineer?s evaluation, and this can be costly. While I do know that there are many qualified and honest foundation contractors out there, it is the engineer who has been trained to properly diagnose the problem, understand what is causing the movement to take place, and to create detailed specifications on the proper repairs. It is with the engineer?s drawings that you can then find several contractors to bid on the project and repairs. Now your bids should be comparing apples to apples, not four different methods of repair, and four wildly varying prices for them all.

For some reason, homeowners or potential buyers want to save the few hundred dollars for an engineer?s evaluation and drawings, and put the money towards the repair. I promise you, more often than not, the engineer?s plans will be money well spent. It will save you more money, time and headaches in the long run, and ensure that the problem has been addressed properly.

While this is just a brief exposure to foundation cracks, hopefully it can shed a little light on a subject that appears to be a scary and intimidating. Most of the time the movement is within tolerable limits and there is no adverse affects on the livability or the structural integrity of the home. If a foundation has been repaired with the help of a professional engineer and a licensed, qualified foundation contractor and appropriate warranties provided, then re-sell value should not be diminished down the road.

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