Skip to Main Content

Minor Hairline vs Major Foundation Cracks: Causes & Repairs

A dramatic rendering of a house with severe foundation cracks.

Discovering cracks in your home’s foundation can set off alarms in any homeowner’s mind. Questions like: “could the cracks widen?,” “is my home at risk of serious damage?,” and “what steps should I take?” are likely to dominate your thoughts.

The good news is that not all foundation cracks spell trouble. Understanding the difference between structural and non-structural cracks can save you from unnecessary worry and expense. On this page, we explore both types, their causes, and solutions.

What Are Hairline Cracks?

A hairline crack under a window sill.

In the early years after construction, it’s common to spot thin cracks on basement walls, especially around doors and windows. Typically no wider than 3 mm, hairline fractures are mostly harmless. They occur as the concrete settles and shrinks over time, a natural process as it dries and hardens.

These minor cracks usually don’t threaten your home’s structural integrity. They can arise from internal stress within the concrete slab, such as shrinkage cracks that form when concrete loses water and becomes more rigid.

Although these cracks are small, usually less than 1/8 inch in width, they can start from stress points like corners of openings or around embedded items and might stop and restart some distance away. Factors like temperature changes, weather conditions, and moisture accumulation can contribute to their formation.

It’s wise to keep an eye on them since what begins as a cosmetic issue can escalate to a structural concern if water infiltration begins to erode the concrete. Repairing these cracks is usually straightforward, often involving the use of an epoxy injection to seal the crack and shield against future water intrusion.

What Are Foundation Cracks?

A severe exterior brick crack.

Cracks wider than 1/8 inch (or 3 mm) are classified as structural and indicate more serious foundation damage. They can appear as horizontal, diagonal, or stair-step cracks and often follow a symmetrical pattern.

Signs like bulging in the foundation point to substantial structural issues caused by a variety of factors, including saturated soil from heavy rains, construction errors, and soil displacement.

These structural concerns can affect the usability of your home, making it difficult to operate windows or doors, and potentially leading to sloped floors. Beyond reducing structural integrity, such cracks can degrade indoor air quality, encourage mold growth, and allow pests to enter.

Foundation Crack Repair: Tailored Solutions

Identifying the type of crack is crucial. A professional inspection by a foundation repair contractor can determine the nature of the cracks and the appropriate repair strategy.

For non-structural cracks, sealing with epoxy injections is typically sufficient to prevent worsening and water penetration. Structural cracks require more robust solutions, such as:

Get Expert Foundation Inspection and Repair

A certified field inspector from Mount Valley Foundation Services.

Mount Valley Foundation Services offers repair services designed to address any issues your home may encounter. With a commitment to quality and customer satisfaction, Mount Valley Foundation Services thoroughly assesses the nature of your foundation problems.

Don’t let foundation cracks compromise your home’s safety or value. Call today to schedule your free inspection and same-day estimate for any foundation issues. Expert evaluation can lead to effective solutions, ensuring the stability and security of your home.


Michael Wilcher

Michael Wilcher

Michael Wilcher is the Content Lead at Groundworks, helping us to answer all of our customers biggest questions about foundation repair, basement waterproofing, crawl space encapsulation, and concrete lifting. In his free time, Michael enjoys collecting vinyl records, watching Formula 1 Racing, and reading philosophy. He holds an MPhil from the University of Cambridge.

Publish Date:

Last Modified Date:

Mount Valley Service Map

Our Locations

Asheville Location

53 N Market St, Suite 5
Asheville, NC 28801

Augusta Location

630 Ellis Street, Suite 2-B
Augusta, GA 30901

Charleston Location

1850 Ashley River Rd
Charleston, SC 29407

Columbia Location

2110 Commerce Drive
Cayce, SC 29033

Greenville Location

300 South Ave
Spartanburg, SC 29306

Myrtle Beach Location

1704 N. Oak Street, Suite 3
Myrtle Beach, SC 29577