How serious is a crack in a slab foundation?

Author: Garth Mraz  |  Last update: Thursday, July 24, 2025

Any cracks that are larger than a hairline crack could be indicative of a serious problem. If you can put a business card into a crack, it's very likely that the crack isn't just surface-level; it's almost certainly a serious problem that stretches deeper into the concrete.

Should I be worried about a crack in my slab foundation?

Typically, cracks less than 3/16 of an inch in solid concrete foundations or finished concrete are not anything to be concerned with. Concrete cracks, always has and always will. The concern here is what type of crack are we looking at; Shrinkage cracks, settlement cracks, or mechanical cracks.

How do you know if foundation cracks are serious?

Diagonal cracks may suggest uneven foundation settling. These cracks are often wider at one end and can signify serious structural issues, especially if accompanied by other symptoms such as sticking doors or windows.

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.

Can a cracked slab foundation be repaired?

Slabjacking is the Best Way to Repair an Interior Cracked Slab. Slabjacking is a method of concrete lifting, designed to restore a slab to its original position (or as close to it as possible). This is accomplished by drilling holes through the concrete slab and injecting a filler material underneath it.

What Kind of Foundation Cracks Are BAD??

When should I worry 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.

Should I worry about hairline cracks in concrete slabs?

In general, hairline cracks are not often a structural problem. However look for cracks that are wider than 1/8 of an inch, cracks that are wider at one end than the other, cracks that extend a long distance across the slab, or cracks that increase in size over time.

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.

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 ...

Does homeowners insurance cover foundation problems?

Homeowners insurance generally pays for foundation repairs that result from covered events. However, if the cause of the damage isn't covered in your policy, repairs probably won't be either.

What size of foundation crack is a concern?

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.

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 does a bad foundation crack look like?

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.

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 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.

How much does it cost to fix a cracked slab?

The cost of slab foundation repair will vary depending on the type of work needed. Minor jobs can cost as little as $1000, whereas extensive repairs can exceed $10,000. The best way to save money on slab foundation repair is to address the underlying problem as soon as possible.

Are cracks in concrete slab normal?

Normal Cracks

These cracks are not a cause for concern and are considered part of the normal aging process of a slab foundation. Over time, concrete naturally dries and hardens, which can result in minor cracking. Such cracks are often superficial and do not impact the structural integrity of the foundation.

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.

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.

How long should concrete last before cracking?

How long should new concrete last before cracking? New concrete can crack within 12 hours of finishing, as it can be a common occurrence as the concrete dries and cures. Certain weather conditions and temperatures can slow or speed up the cracking.

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.

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.

How big of a crack in foundation is a problem?

Large cracks (also called major foundation cracks) are wider than a quarter-inch. These cracks continue to expand and are clear signs of a serious foundation issue.

Why not buy a house on a slab?

One of the most significant potential disadvantages is if the slab cracks. This can substantially compromise the structural integrity of the house and be difficult and expensive to repair. Among the factors that can result in a slab cracking are tree roots, soil displacement, earthquakes, or frozen ground.

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