What Is Slab Jacking?

Slab Jacking Concrete

Slab jacking concrete is exactly as it sounds. It’s the process of jacking up a slab of concrete.

But much like a sinking concrete slab, what it looks like on the surface isn’t the entire story.

You see, there are many different methods of slab jacking or levelling concrete slabs.

To help streamline this a little bit, we’ll focus on the two main categories, mud jacking and polyurethane foam jacking.

Before we get there though, let’s try and understand why slab jacking your concrete may be required.

Concrete is Heavy

Concrete is heavy sounds rather obvious, doesn’t it? Well all that weight is often why slab jacking is required.

When you’re adding hundreds of pounds of weight to a small area, it can cause the surface underneath to shift over time. In certain areas, like Calgary for instance, much of the ground here is very susceptible to shifting.

The majority of the Calgary region seems to be a layer of topsoil with a secondary layer of clay like material within a few feet of the surface. Due to this, you have a top layer that moves much more than the lower clay like area and when you add several hundred pounds of concrete on top that shifting can accelerate.

Obviously concrete workers aren’t intending to make your sidewalk or driveway uneven, but over time it happens anyway as the ground underneath shifts and moves due to that added weight.

Concrete Is Sort of Water Resistant.

While not entirely true, concrete is much more water resistant than typically what is surrounding it. That’s the ground, the gravel, or the lawn or the flower beds right beside it.

When you get stronger run offs during the spring, or rainy times, the water tends to flow to the areas of least resistance. This would be across (or even under) the concrete and then usually down the sides where it can erode the supporting ground.

Once that supporting ground starts to wash away it accelerates problems like uneven cement.

We already know it’s heavy, and now that you’ve started to wash out the surrounding area, it’s much easier and faster for the ground underneath to shift because you end up with more weight concentrated over a smaller area.

This type of effect can happen very quickly or even unexpectedly after and during harsher winters and springs. Something we’re becoming very familiar with here in Southern Alberta!

Concrete is Strong

Here’s another important yet often forgotten reason why concrete is uneven. When one area underneath the concrete shifts the remaining concrete slab doesn’t tend to flex.

That means the opposite end that isn’t sinking tends to raise up.

Over time, and if the underlying problem isn’t dealt with, and even though concrete is quite strong, due to it’s weight you eventually end up with concrete that cracks. Once concrete cracks, it opens itself up to further problems.

The cracks can allow more water to enter underneath the surface and potentially wash the footing away even faster. It can also allow water to build up within the cracks themselves. During colder nights, this could result in freezing water which either expands the size of the crack, or could break down the concrete itself faster.

Both of these issues are undesirable and can lead to costly repairs. This brings us around to the solution to fix your uneven concrete problem, slab jacking.

Mud Jacking Versus Foam Jacking Concrete Slabs

We already explained the basic premise of slab jacking, it’s jacking up the concrete.

What we didn’t talk about is how it’s typically done and that is usually either by doing what is called mudjacking or polyurethane foam jacking.

Both of these processes involve coring a hole (or multiple holes) in the slab and then injecting either a slurry of mud and concrete mix or polyurethane foam under the concrete.

As the material fills the void under the concrete the pressure forces the concrete to lift and the filling continues until the cement slab levels out.

Now both of these products have their pros and cons. And they can’t fix every issue, but when you compare it to the price of tearing up and replacing concrete they both provide a great solution.

Pro’s of Mudjacking

The biggest pro of mudjacking is it’s very cost effective. Mud and cement slurry are relatively cheap and readily available which makes it often the most affordable solution.

This is what makes it so attractive to individuals with a limited budget or looking for a quick fix.

There are also plenty of companies who provide this service making it easy to find someone to compete the work. This allows you to get the work completed fairly quickly.

Con’s of Mudjacking

Unfortunately many of the cons of mudjacking outweigh the benefit of cheap costs and fast service.

The biggest issue is that it’s heavy. If the original reason your concrete slab settled or continues to settle is due to the weight of the slab, adding additional weight underneath won’t fix the problem, it will simply aggravate it and accelerate it.

The second challenge is water. If the reason the concrete shifted is due to water runoff or water issues, what do you think that water will do to mud? If you answered wash it away you can already see the problem.

It’s won’t happen immediately as the cement slurry will harden, but it doesn’t harden with the strength of a regular concrete pour, so if the original water issue is still there it’s just a matter of time before erosion re-creates and likely magnifies, your original problem.

Another issue people have is the coring holes mudjacking leaves behind. The mud used for this process includes a light gravel to help add stability. Because of the gravel, the holes required to inject the mud need to be larger.

If this is a highly visible area like a front sidewalk or driveway these larger holes can be quite obvious and detract from the curb appeal of your home. If you’re spending money to improve the look of your sidewalk it’s rather counter productive to have multiple twoonie-sized holes all over your concrete.

Of course, if you don’t have any of these concerns or issues, mudjacking may be perfect to get your concrete slab levelled and functional. But then if you do have one or more of these issues, a better option is polyurethane foam jacking.

Pro’s of Polyurethane Foam Jacking

The biggest pro of polyurethane foam is it’s weight. It’s incredibly lightweight, while still remaining strong and long lasting.

One of the original concerns people had about polyurethane foam was it would compress, just like styrofoam, over time and if it was used for something heavy like concrete it would just cause more issues. Well, that’s where technology came in.

The chemists and engineers behind the specific foam used for jacking up concrete understood these issues and devised specific formulas designed not to compress, that would set up rapidly and that can handle large amounts of weight.

Bottom line it doesn’t compress and is pretty well a permanent solution. Permanent enough to outlast the structures on most properties and likely to last well beyond the lifespan of the concrete slab itself!

Being lightweight it solves the problem of increasing the weight on an already shifting footing.

The second pro is it’s it’s impervious to water.

Once the foam sets (which is typically less than 60 minutes) water cannot penetrate it. It simply bounces off.

This means the foam won’t go away and will provide a long term stable footing for the slab. It doesn’t mean you still don’t need to correct the water issue as ongoing water can still wash away the footings the foam is sitting on, but it won’t go away.

Third the chemicals involved in the process of creating the foam are injected through a much smaller hole. The two components are liquids and mix together underneath the concrete where they expand and lift. These holes are just over half an inch in diameter (about 16mm) and blend much nicer creating better curb appeal.

Additional benefits include how quickly it sets up, cures within 60 minutes under normal weather conditions, and work can be completed even if the ground isn’t dry.

Too good to be true? Well there are a couple of things to be aware of when dealing with polyurethane foam.

Con’s of Polyurethane Foam

When it comes to cost, some people might choose mudjacking over polyurethane foam to save money.

Before you start panicking though, we’re not talking two or three times the cost of mudjacking, but rather 20-30% more in most situations. The foam designed to lift your concrete and to provide a basically permanent solution simply costs more than mud and cement slurry. It also provides far more benefits in the long run.

The second challenge you may face is that the equipment to inject the materials under the concrete slab is also much more specialized. That means there are fewer companies currently available to provide polyurethane foam jacking.

As a result,  we’re quite busy so if you’re serious about fixing an issue with a sinking concrete slab, driveway or sidewalk, you may want to contact us right away.

FREE Slab Jacking Quotes

It’s hard to make a decision if you don’t know what it will cost you, that’s why we offer free quotes.

So if you understand you have a concrete problem and realize you need to deal with it, you will want to reach out to us and arrange to have us come by and provide a quote. You can use our handy quote form (Click to Arrange a Free Slab Jacking Quote) or you can call us directly at 403-620-7444.

If you’re still unsure if you need slab jacking or to raise or fix your concrete, you may want to read our article about 8 Important Reasons to Raise Your Concrete!