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Rochel Maday is a contributing writer for USA TODAY Homefront. She specializes in home improvement topics and is dedicated to providing valuable information that empowers homeowners to tackle their projects with confidence. Her work has been published in Angi, Bob Vila, Forbes and elsewhere. When not writing, Rochel enjoys digging into gardening projects and watching documentaries with her husband and their four kids.
Foundation cracks are caused by settling, soil pressure, poor drainage or tree roots.
Hairline, vertical, diagonal, horizontal and stair-step are all types of foundation cracks.
Small cracks can be normal due to settling, but larger cracks that let in water are concerning.
While foundation cracks can be concerning, spotting a fissure on your basement wall doesn’t mean your house is doomed. However, as a homeowner, it’s important to understand the different types of foundation cracks, what they relay about your home’s structural health and whether or not you need your foundation repaired.
We spoke with Joshua Parrish, co-owner of Hammer and Handsaw and licensed residential contractor, and Saddat Abid, senior property buyer and CEO at Property Saviour. They shared their expert insights on identifying different types of foundation cracks and knowing which ones need immediate attention.
If you’re worried about foundation cracks, this guide will help you identify minor issues versus serious problems to develop an appropriate plan and handle repairs like a pro.
Foundation cracks pop up in a range of shapes and sizes, and various types can signal different potential issues with your home’s concrete foundation. While some cracks are simply due to natural settling, others can signal serious problems that need immediate attention.
You can’t repair a foundation crack until you know the cause and type. Here’s a look at the most common foundation cracks and what they mean.
Hairline cracks
Horizontal cracks
Vertical foundation cracks
Diagonal cracks
Stair-step cracks
Hairline cracks are thin, uniform cracks commonly appearing in new foundations as they settle. They are typically harmless and can form days or weeks after the concrete cures.
While they are usually not a cause for concern, hairline concrete cracks that expand or allow water to seep into a basement or crawl space should be further inspected. For minor repairs, masonry crack fillers are usually enough to remedy the issue.
Horizontal cracks run parallel to the ground and are typically caused by significant soil or water pressure against the foundation. They can be a serious issue and may indicate that the foundation walls are bowing or buckling under pressure.
If you notice horizontal cracks, schedule a professional inspection immediately to prevent further damage.
Vertical cracks run straight up and down the foundation wall or at a slight angle. Unlike horizontal cracks, vertical foundation cracks usually don’t pose a significant threat unless they start to widen or grow in number. They are often caused by small changes in groundwater pressure from the soil expanding and contracting.
If a vertical crack widens beyond the thickness of a coin, it’s advisable to seek professional assessment. Otherwise, they can often be repaired with DIY methods like polyurethane or epoxy injections.
As the name suggests, diagonal foundation cracks run at an angle across the foundation wall. These cracks can occur in concrete and block foundations and typically indicate that the foundation is moving or shifting.
Diagonal cracks are not always an immediate cause for concern but should be monitored closely. If they widen or multiply, get a professional’s opinion.
Stair-step cracks appear in block foundations and are usually caused by foundation settlement or shifting soil. They’re easy to spot since they appear in a pattern resembling stairs.
While stair-step cracks in the mortar joints may not be immediately concerning, if the cracks extend through the blocks themselves or allow water to seep through, it’s essential to get a professional evaluation. Repairing these cracks often requires specialized techniques to stabilize the foundation and prevent further movement.
Understanding the difference between normal wear and tear and serious foundation issues is important. If you wait too long to address a dangerous crack, the damage could be catastrophic.
While some foundation cracks can be repaired with simple DIY methods, others signal more serious problems that require professional attention. Here’s how to spot the difference between nonstructural cracks and structural cracks.
Nonstructural cracks
Structural cracks
For peace of mind and safety, call a professional when you notice structural cracks. “Normal cracks are typically thin and vertical, less than 1/8 inches wide, and don’t change in width over time,” Abid said. “However, repair is needed for wider cracks, horizontal or stair-step cracks, and those that show warning signs like sticking doors and windows, uneven floors or moisture intrusion.”
Foundation cracks can occur for a variety of reasons. “In most cases, foundation cracks result from several factors acting simultaneously,” Abid said.
Understanding the causes can help you take preventive measures when possible. Here are some common causes of foundation cracks:
Along with routine home inspections, regular foundation inspections can help catch potential issues early. Homeowners should check around their home at least once a year, or maybe twice as the seasons change in the spring and fall, according to Parrish. Here’s a simple guide to performing a DIY foundation inspection:
Step 1
Step 2
Step 3
Step 4
Step 5
First, gather tools. You’ll need a flashlight, a tape measure, a notepad and a camera to document any findings.
Start by walking around the exterior of your home. Look closely at the foundation walls for any visible cracks or signs of damage. Use the flashlight to inspect areas that are harder to see.
Check the inside of your home. Inspect the basement or crawl space, looking for cracks in the foundation walls, floors and along mortar joints. Pay attention to any signs of water leakage or moisture.
Measure and document your findings. Use the tape measure to determine the length and width of any noticeable cracks. Record their location and size in your notepad, and take clear photos for future reference.
After recording everything, check for other signs of foundation problems, such as uneven floors, sticking doors or windows and any new gaps around window or door frames.
If your findings were minor, nonstructural cracks, handle the foundation crack repair yourself with a DIY kit. For larger or structural cracks, call a professional for a thorough assessment and peace of mind.
Here are practical methods for foundation repair, along with recommendations for the type of cracks each technique is best suited for.
Epoxy injection bonds the crack and restores the concrete’s original strength. This method is best for vertical or diagonal cracks but unsuitable for actively leaking cracks.
Polyurethane injection is flexible and good for sealing cracks that might still move. It stops leaks and is used for nonstructural cracks that let water in. It works well for horizontal, vertical and diagonal cracks.
Caulk is a simple, cost-effective solution to fill small, nonstructural cracks and prevent water from entering. It works well for minor cracks, such as hairline cracks or small vertical cracks in concrete.
Sealants provide a flexible barrier that can handle minor movements, making them ideal for filling hairline cracks and keeping moisture out. Both of these approaches are extremely DIY-friendly.
Carbon fiber straps are strong, lightweight materials applied to the surface of a foundation wall to stop it from moving. They are very strong and good for fixing horizontal or diagonal cracks caused by soil pressure.
Wall anchors help stabilize and strengthen bending walls due to soil pressure. They support and prevent more damage, making them ideal for severe horizontal cracks.
It’s best to let a professional handle the repair in some scenarios. One option is underpinning, which involves extending the foundation depth or distributing the load to more stable soil layers. This method is used for homes experiencing significant settlement, often causing large vertical or diagonal foundation wall cracks.
Helical piers are screwed into the ground to support and stabilize a foundation. They are effective for homes built on unstable soil and are used to address significant settlement issues that can cause large structural cracks. This method requires professional installation.
Remember, hiring a foundation repair contractor or structural engineer is always the next best step for larger structural cracks, or if you’re unsure of the severity. “Addressing serious foundation issues should always be left to a professional to prevent any further damage to the home,” Parrish said.
Once you’ve repaired a foundation crack, the next step is to stay proactive. Regular maintenance and preventive measures are your new besties.
Start by ensuring your foundation is properly waterproofed. This includes using sealants, installing sump pumps and applying protective membranes around the foundation. Also, make sure your gutters and downspouts are clear and direct water away from your home’s foundation, and consider proper landscaping to grade the soil away from your home to reduce soil pressure.
Conduct regular inspections of your foundation to catch early signs of cracks or damage. Address small cracks immediately to prevent them from becoming larger issues. This is especially true in a new home, where natural settling can cause foundation problems that need early intervention.
While preventive measures can help protect your home and avoid costly repairs, some foundation cracks are unavoidable. If you notice a foundation crack in your basement walls, don’t hesitate to contact a professional. A foundation repair expert can assess the situation and recommend the best course of action to prevent further structural damage.
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Alyssa Trostle is an editor at USA TODAY Homefront. Having read dozens of warranty booklets from every vehicle manufacturer and over 100 sample contracts from third-party providers, Alyssa is an expert in the auto categories of warranty and shipping categories. Alyssa earned an MFA in creative writing with a concentration in creative nonfiction from Chatham University, which honed her skills in writing and editing both creative and professional content. In her spare time she enjoys reading contemporary fiction and following Pittsburgh sports.
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