Why Do Garden Walls Crack? 7 Common Reasons

Garden walls are essential when it comes to maintaining your garden’s privacy, security, and aesthetic appeal. So, it’s understandable that you’d be worried if you notice your wall is starting to crack without being able to realize what’s causing it. This ultimately begs the question—why do garden walls crack?

The most common reasons why garden walls crack include a lack of support, wind damage, general aging, and structural issues. However, if a garden wall was built professionally, it shouldn’t show any cracks for at least a few years. Hairline cracks don’t indicate major issues, larger ones do.

The rest of this article will discuss the seven most common reasons why garden walls crack. Be sure to keep reading if you want to learn more!

Common Reasons Why Garden Walls Crack

When trying to figure out what is causing your garden wall to crack, there are a few considerations you’ll want to keep in mind. For example, the climate might have something to do with it. Alternatively, the structure may have been built without enough support, and now it’s struggling to remain in position.

In the following sections, I’ll discuss some of the most common reasons why your garden wall might be cracking. Let’s get into it!

1. Lack of Support

A garden wall that doesn’t have adequate support is much more likely to crack. This, in many cases, means that the soil wasn’t prepared correctly before the wall was built in. It’s also possible for the soil to shift throughout the years, a phenomenon caused by changes in moisture levels.

When soil shifts, it won’t be as supportive to the garden wall and could cause some cracking. Although this problem is most common in house foundations, it can sometimes occur with garden walls as well (mainly if there is lots of moisture in the air and, therefore, in the soil too). This kind of soil is known as expansive soil.

2. Wind Damage

Wind damage is another possible cause of a garden wall cracking. When gusts of wind go against the wall, they can put lots of pressure on it. If the wall is sturdy enough and built to survive different weather conditions, you shouldn’t experience any issues.

However, this isn’t always the case. If your wall wasn’t built to the highest of standards (or if it’s at least a few years old), it might be easily affected by strong winds. Sometimes, a garden wall may get cracked if there’s a hash storm, too.

Having said that, harsh storms can cause more than just cracking. In many cases, storms can severely weaken garden walls and even cause them to collapse (or at least partially).

So if you notice your garden wall is cracked and is also beginning to collapse, one reason could be high winds.

3. General Aging

General aging is another common cause of garden wall cracks. Like all other objects and structures, garden walls experience wear and tear over the years. They have to deal with all kinds of weather conditions, including rain, wind, and snow.

If a wall is several years old, these weather conditions might impact its overall structure. Because of this, it’s not uncommon to notice some cracks in walls that have protected your garden for many years.

If the cracks are thin and small (like hair strands), you shouldn’t have anything to worry about. However, if the cracks are large or visible enough, you may need to hire a professional to look at them.

4. Wet Soil

Another element that can cause cracks in a garden wall is wet soil. This is usually an issue in areas that experience high amounts of rainfall, so if you live in a dry climate, this likely isn’t the issue.

If your garden wall acts as a retaining wall, the soil on the inner part of the structure might be too wet to support it properly. In return, this can cause cracking and collapsing. Therefore, it might look like your wall is leaning outward, away from your garden.

If the cracks and damage don’t appear too severe, you can only monitor the situation and make changes if it gets worse. You should also improve the soil’s drainage by adding weep holes.

The same can be said for a regular garden wall. If you feel like part of the issue is wet soil, you should improve its drainage. If you’re unsure how to proceed, it’s always best (and safest) to ask a professional.

5. Thermal Expansion

Thermal expansion could also be causing cracks in your garden walls. This occurs when an object changes shape and volume due to temperature fluctuations. Therefore, if you live somewhere with warm temperatures, the material may be increasing in size, causing cracking and gaps in the brickwork.

After a while, this can cause aggravation and may lead to structural issues in the garden wall. One indicator that thermal expansion is causing the cracks in your wall is if there’s a vertical gap between the bricks. This may occur throughout the wall or only in one or two areas.

South-facing walls are usually in direct sunlight for much of the day, making them more susceptible to thermal expansion. If your wall is constantly exposed to direct sunlight, it will be challenging to prevent thermal expansion. You could try to shelter it more during the day if you’re worried that it will get severely damaged.

However, like with the other issues, you should contact a professional if you have any significant concerns regarding thermal expansion.

6. Structural Issues

Structural issues can cause cracks in garden walls. You may be wondering what precisely a structural problem entails. In most cases, it would include:

  • Mediocre design
  • Bad building methods
  • Poor planning

If any of the above issues occur, a garden wall will likely experience structural issues.

For example, a garden wall might be too thin for its height. When a wall is a certain height, its thickness needs to be proportional. If it’s not, the wall might become unstable, causing cracks and other problems.

Alternatively, the structure might have been built in a sloppy or unprofessional manner. Maybe you constructed a DIY garden wall yourself or hired someone who didn’t have the proper expertise. This isn’t always the case, but it certainly can be.

Structural issues can be difficult to fix without removing the entire wall and building a new one. However, if the problems are minimal, building a new wall might not be necessary. It would be best to speak with a professional to learn more about your options.

7. Tree or Other Plant Roots

An issue you may have not considered is trees or other plants’ roots. As you may know, tree roots grow and spread over time, much like many other plants.

For example, many types of ornamental grasses are known to be invasive and can spread rapidly across large spaces. If you think your problem is being caused by invasive ornamental grass, you can check out my other article to learn more: How Fast Do Ornamental Grasses Spread?

When an invasive plant (or a newly planted tree) is near your garden wall, it could cause cracks. An invasive tree can spread rapidly without you even noticing (because it all occurs underneath the ground).

Another critical factor to note is that the tree might not even be on your property. In some cases, it could be caused by a tree in your neighbor’s garden. To understand what might be causing these issues, you should speak with your neighbor and a professional who can examine the soil to see if a tree (or another plant) is the root of  the problem (pun intended).

There Could Be Multiple Issues

Although the cause of the cracks might be down to one culprit, there could be multiple issues at play. These issues could include some of the elements mentioned above, but there’s a virtually endless array of factors that can be threatening the structural integrity of your garden wall.

If you believe there are different culprits causing the cracks in your garden wall, it will be harder for you to fix them yourself.

To determine what these issues might be, here are some of the elements you should consider:

  • The weather in your region. If it’s warm and sunny, thermal expansion could be to blame. Too much moisture can also cause problems. On the other hand, high winds could damage your wall as well.
  • How the wall was built. You need to consider who built the wall and how they went about it. Was there adequate planning and design carried out first?
  • The age of the wall. Wear-and-tear is inevitable, and if your wall is particularly old, you can expect some minor cracking.
  • The soil. If the soil wasn’t prepared properly before the wall was built (or if it’s too damp), this could cause cracks and other structural issues.

Final Thoughts

Garden walls crack for many reasons. Some of them include:

  • Wind damage
  • General aging
  • Tree or other plant roots
  • Structural issues
  • Thermal expansion

If a crack is small (the size of a hair strand), you can leave it be. However, if there are significant cracks, you may need to fix them or hire a professional for assistance. Since there might be multiple issues at play, sometimes you might even need to have a new wall built. 

Alexander Picot

Alexander Picot is the principal creator of TheGrowingLeaf.com, a website dedicated to gardening tips. Inspired by his mother’s love of gardening, Alex has a passion for taking care of plants and turning backyards into feel-good places and loves to share his experience with the rest of the world.

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