Why Does a Foundation Crack (& When to Worry)

July 19, 2023

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Homeowners often find themselves wondering, why does a foundation crack? In addition, they might also wonder when it’s time to worry! The good news is that not every crack needs expensive repair. On the other hand, quick intervention is your best choice when it comes to avoiding costly fixes.

A foundation might crack due to:

  • Settling
  • Expansive soil
  • Poor-quality construction
  • Hydrostatic pressure
  • Invasive tree roots
  • Freeze-thaw cycles
  • Plumbing leaks
  • Poor drainage
  • Excessive weight

This is just a brief explanation of why foundation cracks often appear. Reading about these in more detail can ensure you’re keeping your home in good condition from the ground up!

Also, some added details can alert you to when it’s time to call a foundation repair contractor near you. Their expertise also helps you make the right decision about needed fixes. They can also advise on preventative maintenance, to keep cracks from returning.

why does a foundation crack

Why Does a Foundation Crack, In Detail

Check out these foundation crack causes in greater detail. Also, if you’re unsure of anything to do with your home’s foundation, call a pro! They can ensure timely, effective repairs to your property.


Foundation settling is one of the most common reasons for cracks to form. When the soil beneath the foundation compresses or shifts, it causes the foundation to sink unevenly. As the foundation movies during the process, it risks cracks.

Expansive Soil

While some soil might compress, other soils such as clay can expand significantly when they absorb water. Next, the soil then contracts as it dries out. This constant swelling and shrinking exerts pressure on the foundation, leading to cracks.

Poor Construction

Homeowners should remember that contractors mix concrete onsite; manufacturers don’t make the material in a factory! In turn, there’s plenty of room for error when it comes to concrete mixing and pouring. If the contractor doesn’t mix the materials properly or uses inferior quality aggregate and cement, a foundation may be prone to cracking.

Additionally, poor workmanship such as using insufficient reinforcement or inadequate concrete can contribute to structural weaknesses. As a result, it’s vital that homeowners rely on professionals for any concrete pouring they need to have done. Also, have a home inspected thoroughly before a purchase!

Hydrostatic Pressure

Hydrostatic pressure refers to water pressure against objects around it. When soil around a foundation becomes saturated, it builds up hydrostatic pressure against the walls. This pressure pushes against the foundation, causing it to crack.

Tree Roots

Large trees planted too close to a foundation risk damage including cracks. As roots grow, they exert pressure on the foundation, leading to cracks or even movement. Also, those cracks let in moisture that weakens concrete even more. In turn, the foundation is more likely to crack when affected by large roots.

Temperature Changes

Extreme temperature changes often cause concrete slabs to expand and contract. This process often risks cracks over time. This is especially true for concrete already cracked, as those cracks let in moisture, as said. That moisture in the concrete expands and it freezes, putting pressure on the concrete.

Plumbing Leaks

Many foundation repair contractors will tell you that moisture is concrete’s number one enemy! Moisture breaks down cement binders that hold concrete materials together. This process risks weakening the concrete so that cracks form eventually.

Water leaks from plumbing pipes or drainage issues near the foundation can saturate the soil. In turn, this creates pressure against foundation walls, leading to cracks. In some cases, plumbing leaks can mean water dripping down concrete walls directly. This also risks weakening and eventual cracks.

Poor Drainage

Inadequate drainage around the foundation can result in water pooling near the foundation walls. Over time, this weakens the foundation and leads to cracks. Also, poor drainage can allow soil to pile up along the foundation walls. This also adds to that pressure and risk of cracks and other damage.

Excessive Load or Weight

Homeowners should remember that foundations hold up the weight of a home. In turn, they’re planned and installed with the home’s weight in mind. While they can hold some additional weight, they’re not indestructible!

Placing heavy loads on the foundation beyond its capacity risks cracks. These loads include additional stories, sunrooms and other additions, and heavy materials such as stone floors. Before adding any of these to your home, consult with a structural engineer.

why does a foundation crack

How Do You Know If Your Foundation Needs Repairs?

In some cases, a homeowner might spot foundation cracks with a standard inspection. You can usually check cracks along basement walls and its floor or exposed concrete outside the home. However, you might also note signs of foundation damage around the property as well, including:

  • Look for cracks along interior and exterior walls, especially around windows and doors. Diagonal cracks, stair-step cracks, or wider cracks are more concerning than small hairline cracks.
  • If you notice floors are no longer level or have noticeable slopes, this indicates foundation settlement or movement.
  • Doors or windows difficult to open or close may indicate foundation issues. Also, they might jam or show gaps around the frames.
  • Pay attention to gaps between crown molding, baseboards, or door casings and surrounding walls.
  • Bulging or leaning walls suggest foundation stress that needs attention.
  • Check for separations or gaps between walls and the ceiling. These often indicate foundation movement.
  • Cracks in the exterior brickwork or siding indicate underlying foundation issues.
  • Check your property’s soil for standing water or excessive moisture especially near the foundation. If you notice puddling or dampness, schedule a foundation inspection.
  • Foundation problems may risk damp and humid conditions in the home. This excess moisture often risks mold or mildew growth especially in a basement or crawl space.

When Should I Worry About Foundation Cracks?

Not all foundation cracks indicate severe damage needing repairs. As concrete cures, it often settles or shrinks slightly. In turn, you might notice hairline cracks forming. In many cases, these are normal and don’t need patching.

However, a homeowner should schedule an inspection for cracks that meet the following criteria:

  • The width of the crack is important. Hairline cracks or those about 1/16 inch wide are common. However, cracks wider than 1/4 inch could indicate more significant issues.
  • Vertical and diagonal cracks are generally more serious than horizontal cracks. Horizontal cracks might indicate soil pressure, while vertical and diagonal cracks often indicate settlement or structural movement.
  • If you notice multiple cracks in different areas, this can indicate widespread foundation issues.
  • Is a crack growing longer or wider over a short period? If so, this is usually a sign that the foundation is actively moving and requires attention.
  • Suddenly sticking doors and windows can be a sign that it’s time for a foundation inspection.
  • Large or noticeable gaps between walls, ceilings, and floors often indicate foundation movement.
  • Cracks in the exterior brickwork or siding often mean your home has severe foundation issues.
  • Never overlook signs of structural damage, such as bowing or leaning walls.

why does a foundation crack

Is It Normal for a Foundation to Crack?

To some extent, a foundation might crack just due to normal settling as it cures. Also, simple age can weaken concrete so that cracks might eventually form. When this occurs, and the extent of damage, depends on the concrete quality, soil moisture levels, and other factors.

Also, concrete’s strength over the years depends on how well homeowners protect it against damage. For instance, adding proper drainage systems can keep concrete dry and strong, preventing future damage. Waterproof membranes also block moisture from seeping into concrete, preventing premature damage.

How Do You Fix a Cracked Foundation?

Foundation repair methods depend on the damage severity, foundation design and material, and other factors. Note some common foundation repair methods your contractor might suggest:

  • For small, hairline cracks, a contractor might use epoxy or polyurethane injections. These fill and seal cracks, preventing water intrusion and further movement.
  • Specialized concrete repair products can patch slightly larger cracks. A contractor applies a bonding agent before filling the crack with a suitable concrete patching mix.
  • Carbon fiber straps can strengthen and stabilize bowing or leaning walls.
  • In more severe cases, a contract might use steel piers to support and lift the foundation to its original position.
  • For sunken concrete slabs, a contractor might choose mud jacking or slab jacking. The contractor injects a mixture of cement, soil, and other materials under a slab or basement to raise it back to its original position.
  • French drains and other waterproofing measures divert water away from the foundation, relieving hydrostatic pressure.
  • A contractor might need to rebuild severely damaged or unstable concrete walls. This service includes a partial or complete rebuilding of the slab or basement walls as necessary.

Lastly, it’s vital that homeowners always consult with a foundation repair contractor before performing repairs. You don’t want to overlook cracks or assume they’re not dangerous when they’re spreading! Also, a professional might suggest preventative measures such as waterproof membranes and grading, to protect a foundation over the years.

A Word From Our Team

New Braunfels Foundation Repair Experts is happy to help answer the question, why does a foundation crack? Hopefully we’ve helped clear this up. Also, if you’re in the area, don’t hesitate to reach out to our Texan foundation repair contractors. We’ll set you up with a FREE inspection and price quote. To find out more, contact us today.


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