Are cracks in a slab foundation normal?

Author: Salvatore Davis  |  Last update: Wednesday, June 11, 2025

Hairline cracks are usually less than 1/8 inch wide and are typically due to the natural curing process of concrete. These cracks are not a cause for concern and are considered part of the normal aging process of a slab foundation.

When should I be concerned about cracks in concrete slab?

Cracks smaller than 0.3 mm in width are generally not serious and of not structural impact. However, they should be monitored for any growth. Cracks of greater width than 0.3 mm may present structural durability issues.

When should I worry about foundation cracks?

Cracks do become a problem when they're actively changing or shifting — especially if they're becoming wider as time goes on. If you see a crack that is wider than a quarter of an inch, you need to call an expert to make sure your foundation isn't failing.

How serious is a crack in a slab foundation?

Pretty much all larger cracks are a problem. If you notice any cracks that are larger than a business card's width, it's a good idea to call in an expert. It's likely that these cracks are coming from an underlying cause, like foundation shifting, and you may need to tackle those underlying causes.

What is an acceptable crack in a concrete slab?

Cracks that are identified as small and fine (less than 0.3 mm in width), are generally deemed acceptable as part of minor settlement depending on the purpose and intent of the concrete structure, the environment it is placed in, the design-life and the durability design.

What Kind of Foundation Cracks Are BAD??

How can you tell if a concrete crack is structural?

Some signs that may indicate that a crack is structural in nature may be that the crack is ⅛” or larger, a crack is horizontal in direction, the crack has shifted forward, one side of a crack projects out further than the other side of the crack, a wall is bowing, and there may be stair step cracks in the mortar ...

How to fix cracks in concrete slab foundation?

Slab Foundation Repair Methods – How To Fix Cracks In A Slab Foundation
  1. Foam Jacking. Polyurethane foam jacking is one of the most effective ways to repair problems in your sinking or settling foundation. ...
  2. Masonry Patches and Sealants. ...
  3. Epoxy Resin. ...
  4. Slabjacking/Mudjacking. ...
  5. Piling. ...
  6. Steel Piers. ...
  7. Helical Piers. ...
  8. Spot Piers.

What is the life expectancy of a slab foundation?

A foundation can maintain its integrity through timely repairs, soil compaction, and protection. For the average home, foundation should last about 80-100 years before needing to be replaced. But not repairing your foundation will make that number of years a lot smaller for your home.

Is a cracked slab covered by insurance?

Homeowners insurance generally does not cover maintenance issues or wear and tear. So, if a slab leak results when tree roots damage your plumbing, or from plumbing lines that are simply past their prime, a typical homeowners insurance will not pay for repairs.

What foundation cracks are OK?

Some foundation cracks are normal and insignificant, such as small gaps that often occur due to the settling of a house over time. However, not all are normal; horizontal, vertical, or jagged diagonals, widening gaps, or accompanied by other signs like bowing walls or water intrusion are not normal.

When should you walk away from foundation problems?

Multiple failed repair attempts: If a home has a history of foundation issues and nothing's been a permanent fix, think about walking away. Severe structural compromise: If foundation issues have snowballed into other issues, the repairs may be too expensive and complex to handle.

How expensive is foundation repair?

The cost of foundation repair typically ranges from $2,000–$7,500, with a national average of $4,500. The cost depends on several different factors like home size, accessibility to the foundation, and soil stability.

When should I be worried about slab foundation?

Visible Cracks: Large or expanding cracks in the slab, floors, walls, or ceiling may indicate significant structural issues. If you can fit a coin into the crack, it requires immediate attention. Uneven Floors: Floors that are no longer level or appear to be sinking can signal foundation problems.

What are two of the most common cause of cracks in concrete slabs?

In conclusion, cracks in a new concrete slab are not uncommon and are often caused by extreme weather conditions, settling, or soil movement.

Can you pour concrete over a cracked slab?

If you notice any small cracks or minor issues, it's in your best interest to repair them before you pour the new concrete. Otherwise, your new concrete will have the same issues.

Is it normal for the slab to have a crack in it?

Hairline cracks are normal in new concrete. As the new concrete settles, thin hairline cracks open up. While they are usually very thin, they can run very deep in the slab. Minor concrete cracking should be expected when new concrete is poured.

How much does a foundation inspection cost?

Foundation inspection costs homeowners an average of $600 but typically ranges from $300–$1,000. See which factors will impact your total cost. Mark Howey is a licensed California building contractor with more than four decades of experience in the construction industry.

How big of a foundation crack is bad?

Hairline cracks under 1/18 inches are normal, but if you spot larger or deeper cracks, call a pro immediately. Cracks exceeding 1/4 inches are a sign of more serious structural damage and should be handled by a foundation pro.

How can you tell if a concrete slab is bad?

Signs Your Concrete Needs Repair
  1. Uneven Concrete. When concrete is uneven, this is another of the signs of concrete damage. ...
  2. Windows and Doors That Stick. ...
  3. Sloping and Sinking Floors. ...
  4. Cracking Walls. ...
  5. Signs of Wear.

What type of house foundation lasts the longest?

Poured concrete is the strongest type of foundation for a house. Concrete is incredibly strong and durable, and it can be poured into any shape.

Do slab foundations always crack?

Is it normal to have a crack in your basement foundation? Hairline cracks in a concrete foundation are common and may not be serious. These cracks often occur within the first couple of years as the concrete cures. However, cracks that are larger, diagonal, or actively growing warrant professional evaluation.

Is it worth repairing concrete cracks?

Repairing concrete cracks isn't just about aesthetics – it's critical for maintaining the structural integrity and longevity of your concrete. Whether it's a driveway, sidewalk, or patio, understanding how and why you should seal cracks and joints can significantly extend the life of your concrete.

Are hairline cracks in concrete foundation normal?

Some cracks in the foundation, including hairline cracks, are considered normal foundation cracks. These typically appear due to settling or concrete shrinkage. Other types of foundation cracks might indicate a serious structural problem.

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