What Causes Foundation Cracks

There are two types of foundation cracks: structural and non-structural.

Structural Cracks

When a crack occurs in the foundation, it is termed as a structural crack as it poses a risk to your home’s structural soundness. These cracks are triggered by the following factors:

Differential settlement: As a house settles into the soil beneath it, some areas may settle more quickly than others, resulting in sloping floors, bowing walls, sticking windows/doors, and mainly cracks. This type of settlement is known as differential settlement.

Hydrostatic pressure: When water penetrates the soil surrounding a foundation, it can create hydrostatic pressure, which can cause cracks in the walls if the water is not properly drained away.

Frost-heave: Freezing soil around a foundation can cause the ground to rise and fall as it thaws, leading to wall cracks due to the up-and-down motion.

Moreover, foundation cracks can also emerge due to various other reasons, such as expansive soils, formation of voids underneath the foundation, soil incapable of providing sufficient support to the foundation, poorly compacted soil, and incorrect grading that leads to water accumulation in the vicinity of the foundation.

Non-Structural Cracks

Cracks in a foundation that do not endanger a home’s structural stability are known as non-structural cracks or “waterproofing cracks” since they permit water to infiltrate the property. Typically, these cracks appear in areas such as beneath I-beams, around windows, and in wall corners. The following factors can trigger non-structural cracks in a foundation:

Concrete shrinkage: When a poured foundation dries rapidly, the concrete may shrink and develop hairline cracks.

Aging: With time, a home’s foundation may develop cracks due to the aging process. These cracks are typically small, measuring less than 1/10 of an inch in width.

Structural vs. Non-structural Foundation Cracks

Foundation cracks always indicate that something has gone wrong and it is crucial to determine whether the cracks are structural or non-structural in nature. Therefore, your primary goal should be to identify the type of crack your foundation has developed.

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    Indications of Structural Cracks:

    To identify structural cracks, watch out for the following signs:

    •  – Cracks that measure over 1/10 of an inch in width.
    •  – Stair-step cracks in concrete block or brick walls.
    •  – Horizontal cracks running along your foundation walls.
    •  – Multiple vertical cracks running parallel to each other.
    •  – Significant diagonal cracks at the corners of your walls on both sides.
    •  – Cracks running across your ceiling and extending down the walls.


    Indications of Non-Structural Cracks:

    To identify non-structural cracks, observe the following characteristics:

    •  – Cracks measuring less than 1/10 of an inch in width.
    •  – Vertical isolated cracks extending from the top to the bottom of your foundation wall that do not change in size.
    •  – Cracks present in a single block of concrete.
    •  – Thin cracks visible near windows, wall corners, floors, or in longer sections of your foundation.

    Foundation Crack Repair Methods

    Structural Cracks:

    In the Houston area, the most common foundation repair method for houses built on concrete slabs and on a pier-and-beam foundation is concrete piers.

    Concrete Pier Installation:

    When installing concrete piers, several holes are drilled beneath your home to a depth that guarantees each pier is anchored in stable stratum. Once all the holes are drilled, a hydraulic press is used to push the piers into the ground until they reach the “point of refusal.”

    Next, workers will employ a unified hydraulic jacking machine connected to a series of hydraulic jacks to elevate the home to its proper height. After elevating the home, steel or concrete shims will be used to fill the gap between the foundation and the top of each pier.

    The number of piers required for repairing a pier and beam foundation depends on the extent, type, and location of the damage. Since the concrete piers are placed at specific intervals, as specified in the structural plan, the whole structure is uniformly supported across the entire footprint area. This ensures a more stable structure and reduces the likelihood of future foundation problems.

    Non-Structural Cracks:

    There are several methods for repairing non-structural cracks in the Houston area.

    Epoxy Crack Injections: One method for repairing foundation cracks is epoxy crack injections. The process involves creating a surface patch with an epoxy bonder, followed by injecting the crack with a 2-part epoxy. This not only waterproofs the foundation but also reinforces it.

    Carbon Fiber Staples: Another option for non-structural cracks is to use carbon fiber staples. The staples are inserted into grinded slots and then fused with the concrete using a high-strength epoxy. This helps prevent the cracks from expanding further.

    AAA Foundation Service

    If you live in the Houston area and are noticing cracks in and around your foundation, there is only one call to make. Trust the professionals of AAA Foundation Service to provide honest information about the issues you are facing. Call us today and we will get you setup with an in-depth inspection, free repair estimate, and a list of solutions.

    Chris Bartlett
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