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Your home’s foundation—the concrete walls surrounding a basement or crawl space, or the concrete slab on which the home rests—supports the entire weight of the house, so it’s natural to be concerned if you discover cracks in the concrete. Fortunately, many foundation cracks are not serious enough to warrant professional attention, and repairing a foundation crack can be a DIY task as long as the crack doesn’t threaten structural integrity.
“When people become concerned about these, they often Google them, and because of the tremendous marketing spend of the foundation repair industry, the first and most likely to pop up are foundation repair contractors. They will in turn send out a commissioned salesperson,” says Bob Brown, a certified foundation repair specialist who’s been certified by the National Foundation Repair Association and the author of Foundation Repair Secrets. “An experienced forensic foundation repair engineer can objectively and fairly determine what is needed in a specific home with signs of distress.”
The best way to ensure that a crack isn’t a sign of a major structural issue is to have a foundation contractor or structural engineer look at it. There are some rules of thumb to keep in mind, however, that can help you decide whether or not you should worry. Is your crack worth worrying about, and does it need the attention of a foundation crack repair pro? Keep these rules of thumb in mind.
Do you need to repair all foundation cracks?
No, not all foundation cracks need to be repaired. Because basement floors are poured after the walls are poured, the concrete where they meet doesn’t always bond completely, and this is a common spot for a crack to appear when the house settles. When you notice a new crack that’s not a hairline but still no wider than ⅛ inch, it’s probably due to settling and most likely it doesn’t present a problem, unless it continues to expand. Diagonal and vertical foundation cracks, for example, are usually the result of normal settling and not worth concern.
The problem is, if you do see cracks and call a foundation repair company, you’re probably going to hear that they need to be repaired ASAP. Why? “Foundation repair salespeople almost always find a way to characterize all of these cracks as indicative of needing foundation repair because that is their job,” says Brown. Contact a forensic foundation repair engineer for a fair estimate.
Monitoring Cracks in the Foundation
While some cracks might not be worrisome now, it’s a good idea to monitor any cracks you see, regardless of size.
To monitor a crack, make a pencil mark at both ends and write the date by each mark, or line up a tape measure next to the crack and snap a photo. In addition, measure the width at the widest point and write that on the wall or make a note on the photo. The crack can be up to ½-inch wide and still not pose a problem other than letting in moisture, odors, and gasses.
When to Worry About Foundation Cracks
“In 30-plus years I have seen very few structurally deficient homes,” says Brown. “Most of the problems that I see are serviceability or cosmetic in nature.” Whether the cracks are inside or outside, there are three categories of foundation stress that engineers typically use to classify them:
- Cosmetic cracks are typically hairline in size and are caused by the normal thermal forces of heating and cooling that happen with weather and HVAC systems.
- Serviceable cracks show some signs of stress and are more problematic than cosmetic cracks. While not all need to be repaired, they can allow pests to enter your home, make your home less energy efficient, and could cause a potential home buyer some pause if they’re considering making an offer on your home.
- Structural cracks are serious. It’s the rarest type of crack, but can compromise the structural integrity of a house. This type of crack needs to be fixed.
Also, says Brown, keep in mind that “the position of the cracks are not as important as the grouping. A single crack unless it is ¼-inch or more, is not critical unless it is together with a group of stress.”
While homeowners might not be able to assess foundation cracks the way engineers can, they can look for these types of cracks, which might be cause for concern:
Horizontal Cracks
Horizontal cracks are typically caused by hydrostatic pressure, and typically require assessment by a professional.
Cracks That Change Direction
Cracks that change direction or follow mortar joints in a stair-step pattern need to be addressed. This pattern of crack can indicate that the soil is moving beneath and around the home, putting changing amounts of pressure on the foundation and causing the foundation to move in ways it wasn’t designed to.
Don’t ignore this type of foundation crack. An engineer can drill for soil samples and perform soil tests to figure out what’s happening and how the situation can be fixed.
Large Cracks
Although many larger foundation cracks—and by “large,” we mean, anything more than ¼-inch wide—may turn out to be harmless, it’s a good idea to have a foundation contractor or a structural engineer inspect the foundation to check for structural problems.
How to Repair Foundation Cracks Yourself
While foundation crack repair cost can range from less than $50 for a hairline crack to greater than $8,000 for a serious fix, the method used to repair a foundation crack depends on the type and size of crack. However, if you aren’t confident about the repair or have concerns, “you should call a forensic geotechnical engineer who can advise you in a fair and unbiased way,” says Brown. Here’s how to repair foundation cracks:
Cracks Smaller than ⅛-Inch Wide
When you notice a new crack that’s not a hairline but still no wider than ⅛ inch, it’s probably due to settling and most likely it doesn’t present a problem, unless it continues to expand. Check the crack at least monthly for several months and make additional marks and record dates if the crack expands. If no expansion occurs and no moisture seeps through, the crack is stable and you can fill it with grout, such as Sashco Gray Mor-Flexx Grout Repair, and then smooth it out with a putty knife.
Cracks Between ⅛- and ¼-Inch Wide
Cracks between ⅛ inch and ¼ inch often result from house settling or concrete shrinking within a few months after construction, and so may pose no structural problem. But it’s a good idea to seal them to keep out moisture, soil smells, or even radon gas.
Repairing a foundation crack in this width range is a simple DIY project that involves filling the crack with a caulk that’s compatible with concrete, such as DAP Concrete and Mortar Sealant.
Cracks More than ½-Inch Wide
Repairing a foundation crack that is more than ½-inch wide is something you can repair yourself with a concrete basement crack repair kit, but on the off chance that the crack is due to something more serious, you should get a professional foundation inspection first.
You can also find concrete crack repair kits with all of the tools needed for sealing foundation cracks. If a crack between the wall and floor exceeds ½ inch (some can be 2 inches wide or more), call a foundation contractor who can fill it by injecting an expanding epoxy. If you have a crack like this to deal with, certainly don’t finish the basement before repairing the foundation crack first.
Cracks with Water Inside
If water is seeping through a crack, seal the crack and divert the water. Basements and crawl spaces are normally damp because they’re located below grade (yard level). But when water, not just moisture, actually seeps through a crack, it poses an increased risk of mold and mildew growth.
It’s even more important to keep water away from the foundation wall. This can be done by removing foundation plantings, installing guttering and downspouts, and adding soil to the yard along the foundation to create a 2 percent or more slope away from the house that allows water to naturally run away from the foundation.
If the crack is damp and it’s impossible to make it dry, consult with a professional. They may be able to use a polyurethane injection in the same manner as an epoxy injection to seal the crack.
Cracks that Appear After Earthquakes
Usually used to fix foundation cracks in concrete after event damage from an earthquake or an impact, in situations where movement is no longer present, epoxy injections can be effective at fixing foundation cracks.
This epoxy, however, isn’t exactly the same as the handy two-part epoxy used for crafts and other household repairs. This epoxy is delivered as a pressurized injection and usually comes with injection ports; products like the PC Products two-part epoxy make it easy to deliver the epoxy straight into the crack. First, the crack is cleaned, dried, and then blown with compressed air to make sure it’s free of any debris. Then the injection fitting is set up and the epoxy is injected into the crack until it’s full.
What causes foundation cracks?
Cracks between ⅛ inch and ¼ inch often result from house settling or concrete shrinking within a few months after construction, and so may pose no structural problem. But it’s a good idea to seal them to keep out moisture, soil smells, or even radon gas.
“The cracks in a home that reoccur are almost always a function of the soil pressures on the foundation. So then it boils down to the soil,” says Brown. “Soil is deposited in layers. Uneven layers with different mineral contents, different densities, different affinities and reactions to water and many other characteristics. These layers could have multiple things going on under a single house.”
Warning Signs of Foundation Problems
“The most common signs of stress that people notice are cracks in drywall, doors and windows out of square (pinch at the top on one side with a gap on the other), out-of-square windows, cracked and sloping floors and exterior masonry cracks,” says Brown.
You may also notice bulges in your foundation walls. Foundation walls are reinforced with steel to keep them from moving. In areas with clay soil, the clay can swell when it becomes wet and put intense lateral (hydrostatic) pressure on the wall, pushing it inward and leading to structural cracks that may indicate bigger issues. This is a major problem, and a foundation contractor should be consulted. If the bulge is slight, it might be difficult to see, but you can hold a long straightedge, such as a 6-foot level, along the wall to determine whether the area with the crack is bulging. Even a slight bulge that accompanies a crack is cause for concern and a pro should take a look.
Other signs of foundation problems include:
- Cabinets or counters separating from the wall
- Cracked or leaning chimney
- Nails popping out of drywall
- Separation of walls and floor
Final Thoughts
Here is the good news: Some foundation cracks can be prevented. While we can’t control all of the effects of Mother Nature, there are a number of simple preventive methods that do work and are worth the effort. Unfortunately, the list of ways to prevent cracks includes chores many homeowners don’t exactly enjoy.
Not surprisingly, many of the best ways to prevent foundation cracks involve keeping water away from the house. Make sure to keep drains, gutters, and downspouts clear of debris so water can’t pool near the foundation. If water tends to collect around the foundation during and after rainstorms even when your gutters and drains are clear, consider a landscaping makeover to regrade the yard and to keep plant roots away from the foundation. And to make sure little problems don’t balloon into major headaches, always keep track of and repair small cracks as soon as you notice them.
