Foundation Crack Repair That Addresses the Cause

A foundation crack is a break or split in the concrete or masonry that supports your home. Cracks are not all the same, and their shape and direction usually say something about what caused them. Four patterns are the most common.

Hairline cracks are very thin and often vertical. They usually come from concrete shrinking as it cures and are often cosmetic. Vertical cracks run up and down the wall, sometimes the full height, and a narrow one that stays the same size is often not a structural concern.

Horizontal cracks run side to side and are worth having inspected, because they often mean soil or water pressure is pushing on the wall from outside, which can leave a basement wall bowing inward. Cracks like these are covered in more depth in our guide to basement wall repair.

A zigzag crack along the mortar joints of a brick or block wall usually points to differential settlement, which means one part of the foundation has moved more than another. Cracks are not the only signal. Doors and windows that suddenly stick, sloping or bouncy floors, and gaps where walls meet ceilings can all trace back to the same movement.

In many cases, yes. Homes settle, concrete shrinks as it cures, and Carolinas weather swings between wet and dry seasons. Thin vertical cracks are often the result of normal curing or minor settling, especially in the first few years after construction.

Cracks that tend to be lower concern are thin, dry, and stay the same over time. Cracks that are worth a professional look are usually wider, horizontal, stair stepped, leaking water, or clearly growing, especially when they show up alongside sticking doors or floors that slope toward one side.

When you are not sure which kind you have, a free inspection of the foundation answers the question with no obligation.

Most foundation cracks trace back to the soil. In the Piedmont, clay that swells and shrinks with the seasons pushes and pulls on a foundation year after year. Loose or sandy soils in the Sandhills and along the coast can shift or wash out from under a footing.

Water adds pressure. When the soil around a foundation is saturated it gets heavy and pushes against the walls, which can open larger cracks from water pressure, a frequent pattern on Asheville hillsides and in coastal Wilmington and Leland, where the water table is high.

Construction matters too: weak footings, poor quality concrete, or soil that was not compacted well can crack a foundation within a few years, so a newer home is not automatically exempt. Shrinkage as concrete cures produces thin cracks that are usually cosmetic.

Some cracks do not need repair, and we will tell you when yours is one of them. The cracks that do matter can become more involved over time. Even a thin crack can let moisture into a basement or crawl space, which may lead to dampness and, over the years, rot in nearby wood framing.

If the soil is still moving, a crack can keep opening, and related signs such as bowing walls or sloping floors can follow. A crack found while it is small is often a straightforward injection, while a wall that has kept moving may need reinforcement or piers, which is a larger project.

For a stable crack that needs sealing, injection is the standard approach. Both materials are injected under pressure, but they behave differently once they are inside the wall.

Epoxy is rigid. It cures into a bond that is typically stronger than the surrounding concrete, which is why we use injected epoxy on dry, stable cracks in poured concrete. It does not flex, so it is not the right choice for a crack that is actively leaking or a wall that is still moving.

Polyurethane is flexible. It reacts with moisture and expands to fill the crack, forming a watertight seal that can move slightly with the wall. That makes it useful for cracks that let water in, which is common where the water table is high, like Wilmington and Leland. It seals out water well but does not add structural strength.

When a crack is a symptom of active settlement, sealing it alone will not hold, because the movement that opened it keeps going. The movement is stabilized first. A settling footing is usually supported with steel piers driven to firmer soil, and a wall that is bowing inward may be reinforced with carbon fiber bonded to the wall or held with anchors set in the soil beyond the wall.

Many cracks can be repaired from inside. Hairline and vertical cracks in poured concrete are good candidates for interior repair, sealed with injection from inside the wall with no digging. Horizontal and stair step cracks usually signal structural movement or soil pressure, so an interior seal may not be the whole answer on its own.

A small crack that is dry, stable, and not paired with sticking doors or sloping floors can be a reasonable homeowner project with a sealant kit from a hardware store.

The harder part is the diagnosis. A crack that looks minor can be a symptom of soil movement or water pressure, and sealing it without addressing the cause can hide the problem while the movement continues. Sealing a crack the wrong way can also trap moisture in the wall. If you are unsure which kind of crack you have, an inspection is a simple way to find out.

There is no flat price, because the cost follows the cause and the method. A simple injection on a stable crack sits at the low end. A crack that turns out to be a symptom of settlement costs more, because the movement has to be stabilized first.

The main factors are the length and type of crack, whether epoxy or polyurethane is used, and whether underlying movement needs to be addressed. After a free inspection we provide a written estimate, and financing options are available.