How To Identify and Repair a Sinking Foundation
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Your home’s foundation sits on layers of soil that can shift under the weight of the structure. Some shifting and settling is normal, but a sinking foundation is a serious problem you need to address immediately. This guide covers the warning signs and causes of a sinking foundation, plus steps you can take to remedy the situation.
Depending on severity, leak repair can range from $2,300–$7,300.
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The average cost for sinking foundation repair ranges from $600–$3,000.
GET ESTIMATEWarning 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 below.
Cracked Drywall or Floors
The pressure and distortions caused by a sinking foundation can manifest as cracks in your walls and ceilings, often occurring near corners or around doors and windows.
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:
- Diagonal cracks (45-degree angle)
- Cracks wider than 1/8 inch
- Cracks that are wider at one end than the other
- Horizontal cracks
Gaps Between Walls, Windows, or Cabinets
You may have a bad foundation 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 between the kitchen backsplash and countertop. These fixtures can pull away from the wall and shift when a weak foundation moves and sinks.
Gaps between the floor and wall or between the baseboard and wall could allow moisture and pests inside your home.
Leaning Chimney
You may not notice your chimney leaning when your foundation first starts sinking because it takes years for this structure to shift. However, you’ll eventually see a space between the chimney and your home’s exterior. Moisture can collect in the gap between your chimney and foundation, resulting in mold growth.
Misaligned Doors and Windows
Humidity and temperature changes can cause doors and windows to swell and shrink, making them difficult to operate. However, a sinking foundation or uneven settling could also be the culprit. These issues can put pressure on the frames, causing them to warp or creating gaps. Check for foundation cracks 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 you must identify and address the underlying cause of your musty basement as soon as you can.
Protruding Nails
Another sign of a house sinking is protruding nails in your walls, i.e., “nail pops.” When a structurally unstable foundation shifts, the house’s weight is redistributed, and the extra pressure may cause the wall studs to bend and jut out. If a sinking foundation is behind your nail pops, could see several loose or protruding nails.
Sagging Ceilings or Floors
Floors and ceilings rely on the stability of the walls and beams supported by the foundation. Sinking or uneven settling causes these beams to tilt, twist, or bow, resulting in visible sagging in floors and ceilings. Your floor might develop noticeable dips or slopes in various areas, or you may hear new creaks as you walk around. Similarly, your ceilings might develop dips or appear wavy.
Common Causes of Foundation Sinking
Foundations can sink for several reasons, such as changes in the weather, poor home construction, and soil composition.
Soil Issues
If the soil beneath your foundation wasn’t adequately compacted during construction, it can settle over time, leading to it sinking. Sandy soil can compress under the weight of your home, causing a shift in the foundation. Clay soil might dry and shrink or expand and push upward due to drought, broken water lines, improper drainage, or even tree root activity. The soil underneath your home may also shift if a contractor built your house over swampy land.
Water Damage
Excess moisture is a common enemy of foundations. Water-related problems include poor drainage around the home, plumbing leaks near or under the foundation, and inadequate gutters or downspouts. Flooding or prolonged exposure to standing water can also lead to shifting or sinking.
Natural Disasters
Major flooding events can erode and destabilize the soil around the foundation, causing significant sinking. Seismic activity can also cause sinking. In earthquake-prone areas, even well-constructed foundations can be affected.
Poor Construction Practices
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.
If the foundation wasn’t designed or built to properly support the weight of the structure, it could eventually sink under the pressure. Improper reinforcement or using unsuitable materials can lead to structural weaknesses and eventual sinking.
Failing to install a proper footing is one construction issue that could cause a foundation to sink over time. That’s the problem Mark McCullough uncovered in the video below. Watch him walk host Kevin O’Connor through the problem and his process for adding footings to an existing home:
Assessing Your Foundation Problems
Before deciding on a course of action, you need to determine how serious your foundation issues are. Here are some methods to assess it:
Visual Inspection Techniques
You can perform a basic assessment of your foundation’s condition by looking for exterior cracks in the foundation walls, bowing or leaning walls, and a visibly sunken portion of the foundation. Water pooling near the foundation after rain is also a sign of a foundation issue.
Document any issues you find with photographs and measurements to track changes over time.
Professional Assessment Methods
For a more thorough evaluation, consider hiring a structural engineer. They may use:
- Laser levels to measure floor evenness
- Plumb bobs to check wall straightness
- Moisture meters to detect dampness in walls or floors
- Core sampling to assess soil conditions
A professional assessment can provide a detailed understanding of your foundation’s condition and guide repair decisions.
Professional Foundation Repair Methods
A contractor may be able to lift your home to make repairs if it’s a mild or moderate home 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. The contractor will lift the house using a hydraulic jack and installs beams, or piers, into the ground, stabilizing the structure.
Here’s three piering methods:
Here are two other options to fix your foundation without underpinning:
Should I Hire a Professional for Foundation Repair?
Foundation repair can be expensive, but tackling this project yourself is risky and could result in further damage. For example, homeowners who try to fix their sinking foundation often use a self-leveling compound or concrete haunches. These temporary fixes can actually cause more sinking.
Quick Tip
- A do-it-yourself (DIY) approach may be fine for repairing foundation cracks—especially cosmetic, hairline cracks. However, repairing the cracks without addressing the underlying problem can jeopardize your safety and compromise the structural integrity of your home.
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.
Preventing Future Foundation Issues
Taking proactive steps can help prevent foundation problems from coming back or happening in the first place:
Regular Maintenance Tips
Inspect your foundation annually for new cracks or changes in existing ones. Be aware of any doors and windows that aren’t opening and closing properly. Also, look for signs of water damage or mold in your basement or crawl space and fix any plumbing leaks right away.
Regular inspections can catch small issues before they become major problems.
Landscaping Best Practices
Plant trees and large shrubs at least 20 feet away from your foundation and avoid overwatering plants near your home. Make sure your sprinkler systems aren’t spraying water toward your foundation. Lastly, keep a consistent moisture level in the soil around your home. Proper landscaping can help maintain soil stability around your foundation.
Moisture Control Strategies
You should always install and maintain gutters and downspouts. If your home doesn’t have gutters, we recommend adding them as soon as possible. You should also use dehumidifiers in basements or crawl spaces and apply waterproof sealants to foundation walls. Install a sump pump if you live in a high-moisture area. Controlling moisture is key to preventing many types of foundation damage.
Our Conclusion
A sinking foundation is a serious issue that requires immediate attention. By recognizing the warning signs early and understanding the causes, you can take appropriate action to protect your home. If your foundation is sinking, you need professional intervention and should contact a foundation repair expert right away.
Remember, prevention is always better than cure when it comes to foundation issues. Regular maintenance, proper drainage, and moisture control can go a long way in keeping your foundation stable and your home safe.
FAQ About Sinking Foundations
How serious is a sinking foundation?
A sinking foundation isn’t something you should ignore. Your home’s alignment could worsen and compromise the safety and stability of your home if you don’t address the issue immediately.
When should I be worried about foundation settling?
You should be worried about foundation settling if you notice horizontal cracks on your foundation walls, cracks in your floors, foundation cracks at a 45-degree angle, or gaps between your walls and cabinets. You’ll also want to keep an eye on a sinking foundation if one side of the foundation is higher than the other or if you have a leaning chimney.
Do foundation cracks mean my foundation is sinking?
Not necessarily. Although foundation cracks can be a sign of a sinking foundation, they can have other causes. Hairline cracks, for instance, can occur naturally as concrete cures and may not indicate a serious problem.
How much does it cost to fix a sinking foundation?
It generally costs between $2,200–$7,948 to fix a foundation, with the average cost being approximately $5,074*.
*Cost data via Angi.
Who should I contact first if I suspect a sinking foundation?
If you suspect a sinking foundation, start by contacting a qualified structural engineer. They can accurately diagnose the issue and provide an unbiased recommendation regarding next steps. Avoid relying solely on contractors or general handymen.
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