How to Fix Cracked Uneven Concrete Patio

  • September 27, 2019
  • / By Dale Keese
Overlooking the Lake

These days, many homeowners use concrete for their patios. And, just like other concrete structures, when concrete patios become older, they start to crack or sink because of general wear and tear, erosion or settlement and need fixing. So, the question is, how to fix a cracked uneven concrete patio? 

Overlooking the Lake

While, fixing a cracked and uneven patio can seem like a daunting task; however, it does not have to be. In fact, repairing and leveling cracked, uneven concrete can be a fairly straightforward process. And, the best part is that you do not need to replace the entire patio to give it a new look. You can have your cracked uneven concrete looking as good as new in just one day.

The main issue with outdoor patios is that they settle or sink. And, when the patio sinks or settles, this occurs unevenly in different sections, which results in wobbly, unstable and uneven surfaces. When the concrete surface’s weight is not supported uniformly from below, cracks form in the concrete.

If you leave these issues unattended to and let the patio remain in this condition, it will result in leaning furniture, stubbed toes and overall, you will have an unsightly patio with unattractive cracks on the surface of the concrete.

Why Does the Concrete Patio Settle?

In the first place, why does the patio settle or sink? Usually, before the concrete is installed, the ground is prepared. The earth is compacted using heavy machinery.

Typically, the compacted surface usually comprises of gravel or it will have at least a layer of gravel. This is usually done to prevent the ground from sinking because of the weight of the patio that is installed above. However, sometimes, because of weather conditions and the rainwater eroding the soil below, settlement may occur. It may also occur if the compacting is not done thoroughly or properly.

How to Fix a Cracked Uneven Concrete Patio

In this article, we will discuss some methods of how to fix a cracked uneven concrete patio.

Floor Cracks

Resurfacing the Top

You could consider resurfacing the top of the patio; however, this is only a superficial solution and only hides the real problem. The furrows and cracks on the concrete may be out of sight temporarily; however, the problem of settling and sinking that has left empty spaces under the patio will still exist. And, severe voids will cause the concrete slabs of the patio to rock from one side to another and could result in a potentially hazardous situation.

Slab Jacking

Also known as mud jacking or slab lifting, slab jacking is an option that you can use to fix the concrete slab, irrespective of whether the entire section of the slab or certain portions of the slab has sunk. However, slab jacking is not something that you can do as a DIY project and it may be a good idea to use concrete specialists to carry out the process for you because slab jacking requires expert knowledge and equipment to get the best results.

In the process of slab jacking, the concrete mixture is injected into the cracks and holes and also under the surface of the existing concrete slab to raise it. The mortar mixture fills all the gaps and forces the uneven slabs to rise to the level of the neighboring ones, thus closing any holes or cracks. The mixture hardens and prevents any movement or rocking.

The advantage of this process is that it also fills any gaps below the concrete slab where it has not sunk. At the top of the soil, it will help to consolidate the soft or loose soil that is located along the upper layers and will help to create a solid base that will prevent movement and also prevent water from running or pooling in the foundations. 

However, since slab jacking makes use of mortar, it may be prone to erosion. Also, the final product is rather heavy and the weight may aggravate the problem of settling.

Backyard Pool

Polymer Slab Lifting

Polymer slab lifting is the most recent advancement in the repair of cracked uneven concrete patios. This is an alternative process to slab jacking, which makes use of lighter material and fewer follow-up issues. The process polymer slab lifting is very similar to slab jacking.

The polymer material, polyurethane, is pumped into the cracks and holes of the concrete patio slabs and also under the patio’s surface, where it fills all the voids and binds with the soil. When the polymer material solidifies, it expands rapidly and lifts the surface of the concrete to the level where it should be.

This material used in the process is very light compared to the mortar mixture that is used in slab jacking. Also, the cleaning up is very quick and there are no extra muddy materials which you need to clean or wash away with water. Once the concrete slab is lifted, all you need to do is seal the cracks and then add your finishing touches to the freshly filled and leveled patio surface.

However, one thing that you must keep in mind is that the process of slab lifting, as well as polymer slab lifting, cannot be used for patios that are made of several pavers or smaller stones because it will not be possible to lift several small pieces of stone uniformly.

Patching

If you need to repair only small portions of the concrete, then you can use the process of patching. In this method, a small portion of the slab is removed and then sand is packed underneath to level the slab and support it before the concrete is replaced. The damaged area must be cut and removed using a crowbar.

Then, you must fill in the sand and pack it down firmly using a tamping machine before the concrete slab is put back into place. If you don’t do this, the sand will start shifting and will cause the concrete to sink again. Also, the gap around the section that has been cut must be filled to prevent any water from entering.

Outdoor Decor

Veneering

If any sections are not completely level when you use sand, you can create a new layer on the concrete by using mortar. Make the surface area of the concrete rougher and more textured by using a hammer and chisel. If you are planning to veneer a portion that has been cut out earlier, then use the chisel around the edges which will give you a better finish.

Using a masonry bit, drill small holes on the surface of the concrete. Once you have prepared the surface, mix mortar very thinly and pour it on the surface of the concrete slab and carefully level it. Leave this to cure for around 30 minutes and then finish the surface using a trowel or a brush.

Extensive Veneering

If the entire concrete slab is damaged, then it may be a good idea to veneer the entire surface. To do this:

  • You must first remove all the debris and loose concrete and brush the area and rinse the patio thoroughly with water. For best veneering results, the concrete surface must be as clean as possible.
  • A wooden frame must be built around the concrete slab’s edges so that it protrudes 2-3 inches above the present slab level.
  • You must then place a layer of sand on the surface such that all the depressions are covered and tamp it down so that when the concrete is poured, it will settle down.
  • Then fill the wooden frame with fresh concrete and leave it to cure as per the manufacturer’s directions.
  • Finish the concrete using a trowel or a brush.

Most often, the first thing that crosses a homeowner’s mind when thinking of how to resolve the issue of a settling patio is to just replace it. However, this is not a simple solution. Replacing the patio requires moving all the furniture, plants and other items on the patio and also the landscaping around the structure. And, then you need to spend money on the materials, and labor, among others. Overall, replacing your patio may turn out to be quite an expensive proposition, not to mention time-consuming too.

Wicker Couch with Colorful Pillows

So, the problem of how to fix a cracked uneven concrete patio may call for assessing the situation and evaluating other solutions that are available. There may not be a “one solution fits all” for all situations. If your home has a large patio and you are facing settlement problems, then instead of going the DIY route, it may be advisable to call in the professionals to sort out the problem out for you.

However, whichever method you plan you decide to follow, it is a good idea to fix the problem of your cracked uneven concrete patio as soon as possible to avoid more expensive repairs or replacement of the patio in the future.