How to Fix a Cracked Slab Foundation

Slab in bedroom has sunk almost 2 inches

What does it mean if you have a sagging or sloping floor, but no basement or crawl space?  I’ve read a lot of articles on sagging floors (I’ve also written a few!), and they always talk about how moisture damages the wooden floor structure under the home.  

But it IS possible to have an uneven floor in a home with a slab foundation.  So in this article, that’s what we’re going to discuss.   

Acculevel has been repairing foundations for homeowners since Andy Beery started the company in 1996.  We are a family-owned and operated company that serves Indiana and parts of the surrounding states.  Over our decades in business, we’ve repaired thousands of slab foundation homes, and we believe we have the best work crews in the business.  We also believe that educating homeowners on issues that matter to them is as important as providing high quality services. 

So in this article, we’ll explore how and why a concrete slab foundation cracks, how to repair it with slabjacking, and the pros and cons of the slabjacking repair process.

 

How is a Slab Foundation Built? 

Home construction starts the same way as any other house.  The location is selected, the ground is opened to make room for the foundation, and then the soil is compacted to be a level building surface.  Concrete footers are poured, to serve as the base of the home’s foundation.  

The slab is poured on top of the footers.  Builders may or may not have the HVAC ductwork laid before the slab is installed.  

 

What Makes A Slab Foundation Crack? 

In most cases, it’s water or poor site preparation (If the soil wasn’t compacted thoroughly before the footers were built).  Erosion can wash out the soil below the footer, creating uneven settling in the home.  This means one side of the slab will shift or sink, exerting tremendous pressure on the slab.  Concrete is not a flexible material; if you try to make it bend or curve, it will crack and break.

If the settling occurs along an outside wall, causing the floor to slope down towards that outside wall, slabjacking may not be the only or best repair option.  Sometimes helical piers are a better repair choice in this situation.  This is often the case for settling porches, which can be fixed by either slabjacking or piers

But if the issue occurs in an interior room of the home, slabjacking may be the best solution.  

 

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.  The filler material takes up space under the slab and raises it- or jacks it- to the desired height.  

The terms concrete lifting, concrete leveling, slabjacking, and mudjacking are often mixed up or used interchangeably.  This article clarifies what these terms mean, what they have in common, and how they differ. 

Slab in bedroom has sunk almost 2 inchesThis photo was taken by an Acculevel project manager during a free estimate appointment. 

In the picture above, you can see there is a significant drop in the floor between these two rooms.  We recommended slabjacking to raise the section back into place; our slabjacking crew uses a polyurethane foam to fill and lift the slab. 

slab has been lifted & cracked floor repairedThis photo was taken by an Acculevel crew member, after slabjacking was completed.  

In the ‘after’ picture, you can see that there was a substantial crack in the floor that we repaired and sealed.  The arrows point to the small holes that were drilled to allow injection; these are filled and sealed after installation is complete. 

 

Why Do We Recommend Polyurethane Foam Injection? 

For 20 years, Acculevel relied on mudjacking as our concrete leveling solution; this used a  thinned-out concrete mixture called “mud” as the injected material.  In 2015, we switched to a new technique using a two part mixture of polyurethane foam.  We made this change after significant testing proved the foam was a more durable and effective solution. 

Because the “mud” used in mudjacking uses a form of concrete, it is susceptible to break down and decay like any other concrete material.  Polyurethane foam does not have this issue.  It’s environmentally safe, cures almost instantly, and does not decay.

 

What Are the Pros & Cons of Slabjacking a Foundation? 

We don’t want to give you the illusion that slabjacking is a fool-proof perfect solution.  No solution is perfect, and anyone who tells you otherwise is excessively optimistic or deceitful. But the negatives associated with slabjacking are the same as they would be for other concrete leveling methods.

  1. If your home has a floor based HVAC system, there is a possibility of injecting the filler material into the ductwork and causing a blockage.
  2. You have to relocate everything out of the room, and completely remove the flooring down to the slab.

The added benefits of using the polyurethane foam are significantly different than those of mudjacking, however:

  1. The foam we inject cures almost instantly.  You will be able to walk on and use the space again within minutes after the installation. 
  2. As the name suggests, the foam is a lightweight substance.  It is incredibly dense, capable of holding up and supporting concrete. But it does not add significantly to the weight of your foundation, so it does not risk causing further settling.

 

Want More Information about Slabjacking?

We have an article that explores the various costs and uses of concrete leveling methods here

Our YouTube Channel also has videos demonstrating the slabjacking process, including this one:

 

If You Are Ready to Repair Your Slab Foundation

Please find an experienced contractor that specializes in concrete leveling and schedule an in-home appointment.  We strongly recommend that you verify the company is reputable, insured, and accredited by the Better Business Bureau.  If you’re not how to hire a contractor, or what to ask, please use our detailed checklist of questions you should ask a contractor.

If you live in our service area, please call Acculevel.  One of our knowledgeable project managers will evaluate your home, review the options with you, and provide a free written estimate. 

Click here for a free estimate

 

Kelly Kater

Over her twenty year career, Kelly has worked in a wide variety of fields: secondary education, nursing, biology, elder care, the postal service, multicultural development, and academia. She has developed a skill for translating industry-specific jargon into everyday language. Her goal is to share the knowledge and experience of the Acculevel team with homeowners, in a way that is both engaging and informative.

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