How serious is a cracked slab?

Author: Shemar McGlynn MD  |  Last update: Tuesday, February 17, 2026

Water often comes up from underneath the basement, and if you have a slab crack, water can come in much more easily. You can also notice basement wall bowing and general basement humidity, mold, and mildew. The rest of your home will also have issues related to the foundation slab cracks.

Is a cracked slab a big deal?

Is a Crack in a Slab Foundation Bad? Cracks in a concrete slab can be signs of foundation issues, or they may just be superficial. Structural cracks in cement slab foundations can adversely affect various parts of the overlying structure.

When should I worry about cracks in my slab?

Generally, if the crack is 2-3 mm or less and it's level on both sides of the crack (one side isn't raised compared to the other side) you should be ok. You can get a structural engineer to look if you want for that extra peace of mind.

Can a cracked slab foundation be fixed?

Yes, most cracks can be repaired. Hairline cracks often need simple sealing, while structural cracks may require underpinning or steel reinforcements. Timely repair prevents further damage and keeps costs down, restoring the foundation's stability.

How much does it cost to fix a cracked slab?

On average, the slab foundation repair cost ranges between $3,500-6,500. Prices for repairing severely cracked or sloping slabs can exceed $10,000.

Do Cracks in Walls Mean There's Structural Damage? - Today's Homeowner with Danny Lipford

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.

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.

How to tell if a foundation crack is serious?

Hairline cracks can be easily fixed and are often cosmetic. There are dangerous cracks though. If they're horizontal or at a 45-degree angle, if they're more than an eighth of an inch wide, or if they're wider at one end than the other, it's important to get them checked out.

What is the best way to fix a cracked concrete slab?

Repair Concrete Walkways and Steps
  1. Step 1: Remove the Loose Concrete. Remove any damaged or crumbling concrete. ...
  2. Step 2: Clean the Concrete. Clean the area in and around the damage with a wire brush and broom. ...
  3. Step 3: Position the Concrete Patch Form. ...
  4. Step 4: Mix the Concrete Crack Sealer. ...
  5. Step 5: Smooth the Concrete Patch.

Should I call a professional for foundation crack repair?

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.

What is an acceptable crack in a concrete floor?

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.

How big of a foundation crack is serious?

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 to 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 ...

Can I sue for cracked concrete?

First, in general, a contractor is not liable unless there is a defect in the concrete and that defect arises as a result of a failure to follow the standard of care. As to the defects, surface cracks are not a defect in the concrete, but a natural occurrence because concrete shrinks as it dries.

Should you buy a house on a slab?

There are good reasons for building or buying a house on a slab, such as cost savings and less risk of damage in certain instances. The disadvantages include that heating and cooling units may have to be installed on the ground floor, which takes up living space. There is also a potential for cracks.

When should I be concerned about slab cracks?

If you have a crack running through the surface of your slab that is rather wide, displaced with one side being higher than the other, or clearly separating over time, you should take note.

How much does it cost to repair a cracked slab?

Concrete Slab – Repair Cost

The average cost to repair a concrete slab falls between $1,000 and $10,000. However, if you need underpinning or piering, the costs can be two to three times higher.

What to do if your slab is cracked?

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.

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.

Will insurance cover foundation repair?

Generally, foundation cracks or settling aren't covered by your homeowners policy. Your home's foundation is protected under your policy's dwelling coverage, but only for certain perils/events.

How much does professional foundation crack repair cost?

Foundation Cracks

Foundation crack repair costs between $250 and $800. Some foundation cracks are minor and easy to fix. Cracks wider than ⅛ inch are a cause for concern, and hairline cracks should be repaired to prevent additional water damage.

When to walk away from foundation issues?

It may make a lot of sense to walk away from foundation issues in a home if the cost of repairing the issues is more than what the seller is willing to compensate by lowering the home's price, or if the scope of damage and repairs is over your budget and time-consuming.

What is an acceptable crack in a concrete slab?

The following list of conditions may be considered to help determine the severity of various concrete cracks: 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.

Can I put Quikrete over existing concrete?

QUIKRETE® Concrete Bonding Adhesive (No. 9902) permanently bonds new concrete, plaster, and stucco to existing concrete, plaster, and stucco. Eliminates the need for roughing the surface before the application.

Why has my concrete slab cracked?

As the concrete hardens, which is caused by the cement and water forming bonds, some of that water escapes through evaporation. This reduces the size of the concrete slab, and since concrete is a very hard, tightly bound substance, this loss of material creates stress. This stress can lead to cracks in the concrete.

Previous article
Why do sealed bags expand in the freezer?
Next article
How do I choose the depth of my foundation?