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Cracks in Walls – What Causes Them and How Are They Fixed?

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Looking for information about cracks in walls, what causes them, and how they’re fixed? If so, don’t hit that back button because that’s what this article is about. We’ll review what causes cracks in a wall, which wall cracks you should worry about, how wall cracks are fixed, and more.

What Causes Wall Cracks?

Wall cracks can be caused by a variety of factors, including the following:

  • Age – Old buildings may be more susceptible to cracking, especially if they’re made of materials like stucco or plaster that tend to expand and contract with temperature and humidity changes. These cracks may look unsightly, but they’re not structurally significant.
  • Hydrostatic pressure – Poor drainage around a foundation can cause hydrostatic pressure to build up in the ground and push against the foundation walls. If it isn’t relieved, it can cause the walls to bow inward and even crack.
  • Improperly taped drywall – If the installer doesn’t apply enough joint compound, the drywall tape could come loose and create a wall crack.
  • Uniform foundation settlement – All foundations settle very slightly into the ground after being built. As long as the settlement is uniform, there’s usually nothing to worry about.
  • Differential foundation settlement – Sometimes, for various reasons, a foundation settles into the ground unevenly. This is called differential foundation settlement, and it can cause severe structural damage if it isn’t fixed. We’ll talk more about differential settlement below.

What is differential foundation settlement?

Differential foundation settlement is a phenomenon that occurs when certain parts of a foundation settle into the ground more than others. Differential settlement can cause significant structural damage, manifesting in wall cracks, uneven floors, and doors and windows that no longer open and close correctly.

Some soil types are prone to erosion, which can cause voids to form under the foundation. This can lead to differential foundation settlement, which can cause cracks and other issues.

What causes differential foundation settlement?

Various things, including the following, can cause differential settlement:

  • Expansive soil – One of the most common causes of differential settlement is expansive soil. This type of soil swells and shrinks with changes in moisture content, which can create uneven settling of the foundation. This is particularly common in areas with large clay deposits, as these soils are highly expansive.
  • Erosion-prone soil – This type of soil is characterized by its susceptibility to erosion. This can lead to unstable ground conditions that can cause differential foundation settlement.
  • Earthquakes – Seismic events can also contribute to differential settlement because they cause the ground to shift and move.
  • Improper site preparation – If the soil isn’t adequately compacted before construction, it can create voids or gaps beneath the foundation. As weight is added to the structure, the foundation can sink into these voids, leading to uneven settling.

common causes of differential settlement

Hydrostatic pressure

Poor drainage around a foundation can cause hydrostatic pressure to build up and push against foundation walls. The walls may begin to bow inward and even crack as the pressure builds. Neglecting the effects of hydrostatic pressure on a foundation will eventually result in the need for major repairs.

How to Know When a Wall Crack Is Serious – Structural vs Non-structural Wall Cracks

While some cracks in walls are merely cosmetic (i.e., non-structural), others may indicate serious structural problems requiring immediate attention. We call these structural cracks. Structural wall cracks are usually caused by either differential foundation settlement or hydrostatic pressure. Structural cracks typically appear wider than 1/4 inch, while non-structural cracks are usually hairline.

Examples of non-structural cracks

  • Cracks caused by wood drying after new construction. (Wood shrinks slightly as it dries.)
  • Cracks caused by temperature and humidity fluctuations. These are common in vacation homes.
  • Drywall cracks caused by faulty installation. These are often problems with improper drywall taping.
  • Cracks caused by shrinkage during the concrete curing process.
  • Drywall cracks caused by leaking pipes. The cracks are created as the drywall softens. They’re usually discolored.
  • Vertical hairline cracks in a foundation wall. These are usually caused by shrinkage during the concrete curing process.

structural vs non-structural-cracks

Examples of structural cracks

Structural wall cracks are those that affect the building’s structural integrity. They are caused by a serious problem with the foundation. The two most common causes of structural cracks are differential foundation settlement and hydrostatic pressure.

  • Stair step cracks in a brick or masonry wall
  • Horizontal wall cracks
  • Diagonal wall cracks from the corners of windows and doors
  • A crack that runs across the ceiling and down a wall
  • A floor crack that goes from wall to wall

Structural cracks must be addressed urgently to avoid further damage and potential safety hazards. Non-structural cracks, meanwhile, can be repaired through simple maintenance measures.

Should I Worry About a Crack in the Wall?

You should worry if the wall crack is structural. If you suspect a wall crack might be structural, it’s essential to have it inspected by an experienced foundation repair contractor, as ignoring structural cracks could lead to further damage and costly repairs. While not all wall cracks are cause for alarm, it’s prudent to err on the side of caution and seek professional advice if you have any concerns.

How to Repair Wall Cracks

While some cracks in walls are merely cosmetic (non-structural cracks), other cracks may indicate serious structural problems requiring immediate attention.

The chosen repair solution for a wall crack will depend on the cause. Here are some common repair solutions for wall cracks:

Possible repair solution for wall cracks caused by differential settlement

Structural cracks caused by differential settlement are usually repaired via a procedure called underpinning. This involves using push, helical, or slab piers to extend the foundation down to load-bearing soil. Once the piers are in place, a synchronized hydraulic lifting system raises the foundation.

Possible repair solution for wall cracks caused by hydrostatic pressure

Structural cracks caused by hydrostatic pressure are often repaired using carbon fiber straps. This process involves attaching carbon fiber straps to the wall, which helps reinforce the structure and prevent further cracking. Carbon fiber is a strong and lightweight material resistant to moisture, making it an ideal choice for wall repairs. Other repair solutions for cracks caused by hydrostatic pressure include wall plate anchors and helical tieback anchors.

How to Prevent Cracks in a Wall

While it may be impossible to eliminate the possibility of cracks appearing in walls, there are some measures that homeowners can take to reduce the likelihood of this happening.

How to help prevent wall cracks caused by differential settlement

  • Proper site preparation before construction – Soil must be adequately tamped down before construction begins. If this isn’t done, the foundation could settle unevenly into the ground after it’s built.
  • Good drainage around the foundation – Poor drainage around a foundation can go a long way toward preventing foundation trouble. Clean your gutters regularly, use downspout extensions, regrade your yard so it slopes away from the foundation, and install a drain tile system.
  • Keep trees away from the foundation – It’s best to keep trees at least 5 feet from the foundation. If the tree/vegetation is known to have an aggressive root composition, it may be best to go with a less aggressive rooted tree/vegetation.

How to prevent wall cracks caused by hydrostatic pressure

The best way to prevent wall cracks caused by hydrostatic pressure is to ensure excess moisture can’t build up in the ground around the foundation. Here are some ways to do that:

  • Clean your gutters regularly so that runoff doesn’t overflow, run down the side of your house, and soak the ground around the foundation.
  • Install downspout extensions to carry water away from your home’s foundation before release.
  • Regrade your yard so it slopes away from the foundation. This will prevent groundwater from draining toward the foundation.
  • Install a drain tile system. When it comes to keeping the ground dry around a foundation, nothing beats a drain tile system.

A drain tile system is a series of pipes buried around your foundation to divert water from your home. This system helps to prevent excess moisture from building up in the soil and causing damage to your foundation.

For more information, see What Homeowners Need To Know About Landscaping Next To Their Home’s Foundation.

If you’re concerned about one or more wall cracks in your Southern California, Arizona, or Nevada home, contact us today to schedule an evaluation.


Brian Dalinghaus

Brian is one of the Co-Founders of Dalinghaus Construction. He has been in the foundation repair industry since 2005. During his career, he has been associated with helping over 4,000 homes and structures throughout California and Arizona.

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