What Is a Retaining Wall, and How Does It Work?

Updated June 6, 2022
A retaining wall made of cobblestone bricks
Photo: davelogan / iStock / Getty Images Plus / Getty Images

Highlights

  • A retaining wall is a structural feature that supports your landscaping and prevents erosion.

  • Retaining walls can be made from different materials including concrete, bricks, stone, and even wood. 

  • There are different types of retaining walls, and which is best depends on your desired design.

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For many of us, the yard isn’t just the space that the house occupies. It’s an extension of the family home, the place where some of life’s most precious memories are made. But what if you could help protect the integrity of your sod and soil, especially in wet conditions? Retaining walls do not only do that, but they can also add functionality and visual appeal to your outdoor spaces.

What Is a Retaining Wall?

Simply put, a retaining wall is a structural feature that allows you to support your landscaping and help prevent erosion. In hilly and mountainous terrain, retaining walls can be used to provide flat grades or even terraced spaces for gardening or recreation—or simply to make your home’s outdoor living space more family-friendly.

If you live in a moist or flood-prone environment, a retaining wall can be essential for preventing your soil from washing away. That means that retaining walls aren’t always about aesthetics. They are also often a matter of safety.

You don’t have to build a fortress to get a retaining wall that works. Even a low wall can serve its purpose well.

The materials you choose for your retaining wall can also vary widely, depending on your personal preference, the purpose of the wall, and the soil and weather conditions. Most walls are made from wood, concrete, brick, or stone.

If you choose to install a retaining wall, though, you should budget accordingly. The cost of a retaining wall can range from $3,000 to $9,000, depending on the size, materials, and location.

What Does a Retaining Wall Do?

One of the primary purposes of a retaining wall is to make your outdoor space safer and more functional. 

Prevents Erosion

It’s pretty tough to grow the garden of your dreams on a hillside so steep you feel like you need rock-climbing equipment to scale it. Even worse, if your landscape seems to wash away with every intense rainstorm, then a retaining wall can provide a wonderful sense of security.

There are other options, of course, if erosion is a concern. On average, it costs less to regrade a yard than to install a retaining wall. But the tradeoff is that the earth moved during regrading will likely continue to shift, meaning you may end up repeating the process all over again. Plus, unlike a retaining wall, you don’t have the structural reinforcement of earth and soil as you do with a stone, steel, brick, or concrete wall.

Adds Visual Appeal

A tiered retaining wall in a house’s garden
Photo: herreid / iStock / Getty Images Plus / Getty Images

You don’t have to be worried about your yard and home slip-sliding away to benefit from a retaining wall, though. Retaining walls can add tremendous visual appeal to your home’s exterior. 

A series of low retaining walls in appealing designs and materials can add levels to your yard, making your landscape look more like an English manor home than a suburb in the heart of America.

Best of all, you can use retaining walls to make mini-terraces expressly suited for all the purposes your outdoor living space serves. Whether it’s cookouts, toasting marshmallows around the fire pit, or relaxing in a lounge chair with a good book, hardscaping with strategically-placed retaining walls can provide ideal dedicated spaces for them all.

Types of Retaining Walls

There are four basic types of retaining walls, and each has its own benefits and drawbacks. 

Cantilever

Cantilever retaining walls create an “L” shape using steel bars and concrete slabs. The soil holds part of the base (called the “heel) down, while a smaller part of the base (the “toe”) sticks out from the earth. Cantilever walls are commonly used in commercial landscaping because of their strength and durability.

Gravity

Instead of using leverage like the cantilever, gravity retaining walls work by using … gravity. Though this is the thickest kind of retaining wall, it’s easy to install and can be made from a variety of materials. Bonus: this type of wall typically doesn’t need any additional reinforcement. 

Anchored

This type of retaining wall is supported by anchors that go deep into the ground. This method is a go-to if you have a thinner wall or if it needs to support a substantial amount of earth. Anchored retaining walls are typically budget-friendly and can withstand pressure for a long time without issue.  

Sheet Pile

If you’re short on space, a sheet piled retaining wall is installed deep into the ground (up to 1/3 of the wall will be underground). This is the thinnest retaining wall and, like anchored walls, can withstand a large amount of pressure. 

Retaining Wall Materials

Just as there are different types of retaining walls, there are also numerous options for what those walls can be built from. Here are a few popular choices.

Poured Concrete

Poured concrete makes one of the strongest retaining walls, and it can be poured into a variety of modern designs. However, it can be prone to cracking and bulging. And, because installation requires very specific, specialized skills, you’ll need to hire a pro to build a poured concrete retaining wall for you. 

Concrete Blocks

While you’ll need a pro for poured concrete walls, homeowners can tackle building retaining walls from concrete blocks on their own. Blocks also make it easy to design curved walls, and you can choose from a variety of different colors. But because of their weight, this material is only OK for walls under 4 feet tall. 

Stones, Bricks, and Other Masonry

Like concrete, masonry is a great long-lasting option for retaining walls. They’re strong, durable, and give your yard a gorgeous, traditional look. That said, this isn’t a DIY-friendly process—you’ll need to hire a professional to do the work right. 

Wood

For a rustic touch, wood retaining walls are the perfect choice. The materials are affordable and accessible, and it’s a simple project for handy homeowners to build. That said, wood is not the most durable material—it can rot and warp. But, if properly installed with thorough waterproofing, this type of retaining wall can last up to 20 years. 

Common Issues (and How to Fix Them)

Everything needs maintenance, and that goes for retaining walls, too. If you encounter any of the following problems, here’s what to do.

Improper Drainage

Drainage is vital for a successful retaining wall. If there’s no drainage, the soil soaks up all the moisture and becomes heavier, putting more strain on the wall. Always add drainage materials such as crushed stone or gravel. Sometimes, you’ll need to add a drainage pipe.

Building Too Tall 

Don’t expect a towering wall of concrete blocks to hold up without extra support. Before building, consult with a pro (even if you’re planning to do the heavy-lifting yourself) on the best type of wall for your desired material and yard. Depending on your needs, you might be able to get away with a gravity retaining wall, or you might need to go all-in on an anchored wall. 

Poor Footing

Footing is an underground structure that supports the retaining wall. If you add a wall without making sure the footing is solid, there’s a strong possibility your foundation will shift and the wall will become damaged. The footing should be deep underground—underneath the wall—and be made of rocks or gravel.

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