What Are the Biggest Problems with Slabjacking?

Slabjacking is the concrete lifting method that we use here at Acculevel.  If you’re not familiar with it, you may want to start with our blog that explores concrete leveling repair methods. 

Before I started writing this article, I asked our project managers and advisors for their feedback.  Since they’re the Acculevel employees who interact the most with our customers, I thought they’d provide the most accurate and authentic feedback.  They did not disappoint. One of my favorite project managers summarized the primary issue with his usual humorous take: “the biggest problem with slabjacking repairs is that we don’t have x-ray vision.”

He’s referring to the fact that, many times, it’s what underneath the sunken concrete slab that prevents us from achieving satisfactory results.  Acculevel is a family-owned and operated company started by Andy Beery in 1996.  At that time, mudjacking was the best- and only- way to lift or level existing concrete slabs.  Since then, another method has been developed.  After extensive testing and research, Andy adopted slabjacking in 2015; this method is similar in process to mudjacking, but uses a lighter and more durable fill material.

We believe that well-informed consumers are the best customers.  We want to provide a detailed and honest assessment of slabjacking as a repair method.  For us, that includes explaining when it doesn’t work well and why.  

Why Do You Need to Know What’s Below the Slab?

Most of the time, what is under your patio/driveway/porch is exactly what you’d expect: gravel and dirt.  Water has eroded some of this base, causing the slab to sink.  This is the ideal setting; we drill through the slab and inject the polyurethane, it foams up and fills the space, and presto! Your slab is lifting, and we get it as close as possible to its original position.

But… sometimes there is more than simple erosion at work.  There are times when a large gap is below the slab.  Occasionally we try to repair a porch that is capped with concrete, only to learn there’s a two foot void below it.  Slabjacking is not a good fit for this type of repair; depending on the situation, you may be better served with helical piers.  

These photos were taken by Acculevel employees, before & after piers were installed to lift a customer’s porch. 

Garages can be a problem for a similar reason.  Some garages have a “floating slab,” which means the garage foundation is separate from the floor of the garage.  (You can learn more about garage slabjacking here.)  If this is the case, we can lift or level the floor with slabjacking.  

But sometimes the slab is incorporated into a traditional foundation with a footer attached (all poured at the same time).  In these instances, you will need piers instead.  Slabjacking will not lift a slab that substantial- it’s too large and too heavy to be an efficient fix.

These photos were taken by an Acculevel project manager during the free estimate appointment.  In this instance, you can clearly see that the floor is all one piece that extends to the outside wall of the garage.  

What can be frustrating about these situations is that we can’t always determine how the slab was poured, before trying to slabjack it.  Sometimes, like the above example, the foundation is above ground enough that the answer is visible.  But many times, homeowners are not so lucky.  

If you are the original homeowner, or have clear and detailed building plans from the original owner, you might have the detailed information needed.  But many times, these documents get lost or left out of home sales, forcing the homeowner and the contractor to guess.

Is There Something On Top of the Slab?

Sometimes, the biggest issue we encounter is weight.  Amenities are often built on slab foundations, because they are features that may have been added after- or built separately from- the primary home.  These are things like gazebos, enclosed porches, sunrooms, fireplaces or detached garages.  

In these instances, slabjacking may not be able to safely exert enough force to lift the slab.  By the time there is sufficient polyurethane fill below the structure to lift it, the strain may crack the slab itself.  You may be better served by either having piers installed, if the entire structure needs stabilizing or lifting.  

However, If it’s only the interior floor that needs repair, for example if the floor is cracked and sloping to one side, there may be another option.  The contractor may be able to cut the interior slab floor “free” of the structure and separate it from the exterior slab.  If this is possible, then slabjacking the floor should be much easier to accomplish.  

Additional Information

The last factor to consider is the condition of the slab itself.  If there are multiple cracks throughout the concrete, slabjacking may not be possible.  We have an illustrated guide that provides examples that you can view for comparison, here.

This article may not have helped you determine if slabjacking is the right repair method for you.  But I hope it addresses some of the concerns you have about your own concrete slab, and explains some of the circumstances that can impact your repair options. 

The Next Step

If you would like a professional evaluation, you should find a qualified local contractor who provides free estimates.  Most contractors will not charge for the initial inspection; you should probably avoid those that do.  Check with the Better Business Bureau to determine if the concrete repair company is licensed and registered with the BBB.  

For more guidance on how to determine if a contractor is a good fit for you, please refer to our article on questions to ask a contractor.  This article provides our answers, and you can download a free copy of the questions to use during your own contractor search.

If you live in our service area, contact Acculevel.  Our friendly and helpful office staff will schedule an at-home appointment with one of our project managers.   While they do not have x-ray vision, they are all knowledgeable and experienced people who will help you determine the best course of action to keep your home healthy and stable for years to come.