Your home’s foundation supports your house and sits on soil layers that can shift under the weight of the structure, resulting in changes in the foundation. Some shifting is normal, but a sinking foundation is a serious problem you should address immediately. We’ll review the warning signs, causes, and solutions to remedy the sinking of your home’s foundation below.

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Warning Signs of a Sinking Foundation

Some warning signs of a sinking foundation include cracked drywall, wall gaps, and a leaning chimney. Learn more about these signs and others in the following sections.

Cracked Drywall or Floors

Cracks in your foundation, drywall, and floors are normal as your house ages, but floor or drywall cracks that have the following characteristics warrant further investigation by a foundation inspector:

• The crack is at a 45-degree angle
• The crack is more than 1/8 of an inch wide
• The crack is wider at one end than the other
• The crack is horizontal

Gaps Between Walls, Windows, or Cabinets

You may have foundation damage if you notice your window frames, doorframes, or cabinets pulling away from your walls. There may also be gaps between your wall and chair molding or the kitchen backsplash and countertop. These fixtures can pull away from the wall and shift when a weak foundation moves and sinks.

These gaps allow moisture and pests inside your home. Moisture within the fissures can cause wood to rot, further damaging the structure, and mold can grow when moisture enters those gaps. Rodents, cockroaches, and other pests can burrow into these spaces, potentially spreading disease and contaminating your food.

Leaning Chimney

You may not notice your chimney leaning when your foundation first starts changing because it takes years for this structure to shift, but you’ll eventually see a space between the chimney and your home’s exterior. Moisture can form in the gap between your chimney and foundation, resulting in mold growth, so address this issue immediately before the mold gets out of control.

Misaligned Doors and Windows

Humidity can cause doors and windows to swell, making them difficult to operate, and a sinking foundation is often the culprit. Check for foundation cracks coming from your windows and doors if you suspect a sinking foundation is the cause for your misaligned doors or windows.

Musty Basements

Moisture can enter through tiny cracks in your basement or crawl space when your foundation shifts, leading to rotting wood and mildew growth. Mold can also grow if you have excess moisture in your basement. Exposure to mold over time could affect your health, so address the underlying cause of your musty basement as soon as possible.

Protruding Nails

Another sign of a house sinking is protruding nails in your walls, which occurs when a structurally poor foundation shifts. When a house’s weight is redistributed, the extra pressure causes the wall studs to bend and jut out.

Sagging Ceilings or Floors

Your foundation could be experiencing external pressure after your house shifts from its original position if you notice sagging floors or ceiling dips.

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What Causes a Foundation To Sink?

Foundations can sink for several reasons, such as changes in the weather, poor home construction, and soil composition.

Changes in Weather

Floods, droughts, and extreme temperature fluctuations can cause foundation problems. Specifically, ice formations can develop under your home when damp soil freezes, expanding and shifting your foundation upward. It’s normal for soil to contract and expand depending on how much water it absorbs, but it can cause foundation issues if the soil wasn’t compacted or prepared properly.

Poor Construction

The U.S. Department of Housing and Urban Development has outlined foundation requirements that home builders must follow when building a home. Homes built more than 50 years ago may not be up to code, which could result in structural damage over time.

Even if a contractor has built your house to code, its foundation can still shift due to mortar joint structures that absorb moisture and shift your home’s foundation.

Soil Composition

Soil conditions can change under your concrete stumps or slab foundation. Sandy soil can compress under the weight of your home, causing a shift in the foundation. The soil underneath your home may also condense and change if a contractor built the house over swampy land.

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What To Do About a Sinking Foundation

A contractor may be able to lift your home to make repairs if it’s a mild or moderate foundation issue. A contractor will cut your house from its foundation and lift it using a hydraulic jack. A wooden, steel, plastic, or concrete crib wall will temporarily support your home while the contractor installs a new foundation or extends the existing one. More severe foundation problems will be more expensive and likely require a combination of solutions to fix the issue.

Most repair methods involve underpinning, which reinforces an existing foundation. You can perform this process in three different ways, all of which include piering. A contractor lifts the house using a hydraulic jack and installs beams, or piers, into the ground, stabilizing the structure. We’ve listed three piering methods below:

• Helical piers: Similar to steel push piers, helical piers use the weight of the house to drive the piers and torque to advance them. The hydraulic system lifts and levels the home once the piers are secure.
• Slab piers: A contractor installs steel or helical piers by drilling holes into the concrete slab. The contractor pushes the anchors into the holes until they hit the stable soil or bedrock, and then steel brackets secure the anchors.
• Steel push piers or resistance piers: The weight of the house and hydraulic pressure drive the steel push piers into the soil. A contractor secures it to a load-bearing strata underneath your home, and then the hydraulic system lifts the building. The contractor removes the jacks once the home is level, leaving the steel push piers to support the structure.

Here are two other options to fix your foundation without underpinning:

• Resin injections: This fairly new process involves grout or resin injections. A contractor injects resin or grout into the void under your foundation slab. You can’t use this treatment unless the foundation is completely dry because the resin won’t bond to the concrete properly. The injections don’t perform well below the water table or in freeze-and-thaw areas. Consult an expert during a foundation inspection before going this route.
• Restumping: Restumping, also known as reblocking, is when the contractor replaces the cracked foundation with a new one. You’ll need to jack the house to get to the stumps, and when a foundation stump is compromised, you can replace the damaged stump.

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Should I Hire a Professional for Foundation Repair?

Repairing a sinking foundation is risky, and doing it yourself could result in further damage. For example, homeowners who try to fix their sinking foundation often use a self-leveling compound or concrete haunches that are temporary fixes that can cause more sinking.

However, a do-it-yourself (DIY) approach may be fine if you have small cracks in your concrete foundation. You could also repair a sinking foundation if a contractor built your home over a crawl space or if your wall cracks are in your center interior walls.

It’s easier to fix small structural issues in interior walls, such as vertical cracks, by filling them with a resin injection. Exterior walls that line your perimeter sit on concrete and require special tools and expertise that most homeowners don’t have, making them much more difficult to repair.

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Our Conclusion

We recommend hiring a foundation repair expert to fix a sinking foundation because most homeowners don’t have the tools to fix it on their own. Also, most don’t have the industry knowledge to repair structural damage. If you plan on taking a DIY approach, you may qualify for financial assistance through the government to help cover the cost of repairing your foundation.

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FAQ About Sinking Foundations

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