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Why Is My Concrete Patio Cracking? (8 Causes of Cracks)

Why Is My Concrete Patio Cracking? (8 Causes of Cracks)

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After a long week at work, you head out to your backyard to unwind and enjoy the sun. However, as you make your way to your favorite chair, you catch your foot and trip.

When you investigate the reason behind the stumble, you’ll notice a few fractures in the patio. At this point, you may wonder, why is my concrete patio cracking?

If that’s the case, then you’re in luck. In this article, we’ll walk you through everything you need to know about the issue.

We’ll also discuss a few solutions for a cracked patio.

What Causes Cracks in Concrete Patios?

Concrete is an incredibly durable material, and it’s also easy to mix and pour. Plus, there are countless designs you can achieve with minimal effort.

Because of that, thousands of people choose concrete for their patios. Yet, this isn’t always the best plan.

After a while of using the deck, you’ll notice tiny cracks and fissures appearing on the surface. There are quite a few reasons why this could be happening to your patio.

So, without further ado, let’s take a look at some of the most common culprits.

1 – Improper Concrete Mixture

To kick off our list, let’s jump into how we make concrete. Few people know that the material is a mixture of three different components.

That includes cement, water, and gravel.

These ingredients come together in specific ratios to create a durable material. Typically, the mixture consists of 10% cement, 20% water, and 70% sand or gravel.

If you alter the concentration of the components, the concrete won’t dry down properly. This can cause cracks to form on the surface of your patio.

2 – Heaving

The moisture content underneath the concrete is another common culprit behind patio cracks. When soil or sand absorb water, they swell up.

As they expand, they’ll push on the underside of the deck. Over time, this will lead to strain on the concrete patio and cause it to warp.

Eventually, the change in shape can result in deep cracks that go all the way through your deck.

This is more likely to happen during the winter since water expands even further as it cools down.

The only way to avoid this issue is to ensure you have the proper drainage. Find a way to redirect water away from the patio to keep the soil underneath dry.

3 – Settling

Settling is one of the most common causes of cracks in a patio. You have to remember, concrete is incredibly heavy.

So, when you place it on top of loose soil, some shifting will occur. This results in an uneven surface with caverns under the concrete.

As you use the patio and add more weight on top, the concrete will settle down into the soil. This movement can affect the structural integrity of the material and lead to cracks.

4 – Premature Drying

As we mentioned, the majority of cement consists of water. That means the liquid plays a significant role in the final state of the material.

This is because moisture is crucial for the process that produces concrete. To help you understand this, here’s a look at cement.

The material acts as the glue that brings concrete together. When cement gets wet, it goes through a chemical reaction that causes it to harden.

To ensure the integrity of the concrete, the reaction has to reach completion. That’s almost impossible to do without enough water.

So, if the cement dries too quickly, it won’t cure correctly. This, in turn, will lead to a few cracks on the patio.

5 – Water Damage

Even though water is one of the main components of concrete, too much liquid can spell trouble.

On the surface, concrete looks like a solid material. Yet, if you use a magnifying glass, you’ll notice thousands of tiny holes across the surface called pores.

These small openings allow water to seep into the concrete.

When that happens, the liquid will travel along the deck and cause the concrete to delaminate. This means that the layers of the patio will come apart.

As you can imagine, this will result in a few deep cracks.

6 – Expansion

The majority of materials expand when you add a little heat. The same applies to concrete mixtures.

After a while in the sun, the material will increase in size. This will affect the integrity of the patio, but shouldn’t cause any cracks.

The real problem appears as the concrete starts to cool. When the material shrinks back down, it stretches and shifts in all sorts of directions.

As a result, fissures can form on the surface of the deck.

There’s only one way around this issue. You have to install expansion joints on the patio.

This will allow the concrete to change its size and return to normal once the temperature evens out.

7 – Shrinkage

When you first mix up a batch of concrete, the material is in liquid form. Then, as the water interacts with the cement, the material will harden.

As the concrete loses moisture, it’ll begin to shrink. Usually, with the correct concrete recipe, the change in size shouldn’t be an issue.

Although, sometimes it leads to cracks. This occurs when the concrete dries unevenly.

If one section shrinks before another, the tension will cause fissures.

8 – Overloading

Most people think that all concrete is the same. They assume any slab of the material can handle the same weight and forces.

Sadly, that’s not always true. There are several types of concrete, each with unique properties.

That means some patios will be able to accommodate more load than others. So, adding too many pieces of furniture can cause a few breaks.

On top of that, you have to think about weight distribution. If you place lots of heavy objects in one area of the deck, you’ll see a few scratches and cracks.

Can a Cracked Concrete Patio Be Repaired?

The answer to this question will depend on the state of your concrete patio. With minimal damage, you should be able to repair your deck.

You can use watered-down cement, or concrete patching compounds, like epoxy. These will fill in the fissures and bind the patio together to increase its durability.

Yet, if the cracks extend throughout the entire concrete, it may be time for a new deck. It can cost more to repair the damaged patio than to purchase a new one.

What to Do With a Cracked Concrete Patio

There are a few types of cracks that can form on your deck. To figure out if you can repair the issue, you have to identify it first.

In this section, we’ll take you through the different crack varieties and how to deal with them.

Hairline Fissures

The most common type of crack is the hairline variety. As the name suggests, these fissures are no wider than a strand of hair.

That means these cracks shouldn’t be a tripping hazard. Instead, they’re just an eyesore that collects dust and other debris.

Thankfully, you can address hairline cracks in a flash. All you need is a bit of epoxy to fill in the empty spaces.

Mid-sized Fissures

Next on our list, we’ll discuss small fissures. These are visible cracks that are slightly larger than the hairline variety.

They’re typically caused by shrinkage or expansion. The cracks can be unsightly, but they tend to be easy to fix.

You’ll need to fill in the empty spaces with more concrete or epoxy. It may also be a good idea to install expansion joints while you’re at it.

This may cost a bit extra, but that way you don’t have to worry about these cracks forming again.

Large Fissures

Large cracks are usually due to settlement issues or extensive water damage. These fissures are wide enough to fit a quarter and travel at least halfway down the concrete slab.

At this stage, there isn’t much you can do about the patio. You can try leveling the ground underneath the deck with foam and other materials.

Unfortunately, this process will be tedious, with minimal success rates. For that reason, it may be better to replace the patio altogether.

Final Thoughts

Why is my concrete patio cracking? There are a few culprits that could be behind this issue.

Some of the most common include premature drying or mixing the concrete improperly. Other than that, heaving, settling, shrinkage, and expansion can also lead to fissures.

Finally, water damage and overloading can cause your patio to degrade over time.


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