Block Retaining Walls
Retaining walls are built to hold back soil, and they’re commonly used where the land slopes and extra support is needed. The weight of the material being held back, called the “backfill”, gives the retaining wall some of its strength. There are various types of block retaining walls, and they come in various sizes and types that can be used for various projects, from garden walls to landscaping features.
When choosing a block retaining wall system, it’s important to consider the required height of the wall and the weight of the backfill. And for a block wall you’ll also need to decide whether you want a solid or hollow wall block, concrete or cinder block, overlapping or interlocked, and more. The choices may seem endless.
With careful planning and execution, a block retaining wall can add function and beauty to your property. Let’s dive in to find out everything you need to know.
Retaining Wall Block Types
The best part about retaining wall blocks is that they come in various colors, shapes, and sizes. That means you can easily find the perfect match for your landscape. In addition, retaining wall blocks can be used to produce a wide range of styles, from classic and traditional to modern and contemporary.
There may be some confusion about terminology used for some of the different types of blocks commonly used for retaining walls. If you’re not clear about terms such as “CMU” or “concrete block”, there’s a very good explanation on the NCMA website.
Here are just a few ideas for block retaining walls to get you started:
Overlapping Concrete Blocks
One of the most interesting ways to use concrete retaining wall blocks is to create an overlapping effect for the wall. This can be done by alternating the positions of the blocks in each row as you build the wall.
As you stack the blocks, you can also allow some of the stones to protrude slightly beyond the face of the wall. This can give the illusion that the blocks overlap, creating a unique and eye-catching look. Also, you can use different colors of stones to create a gradient effect if you prefer.
Interlocking Blocks
Interlocking blocks can also be used to create an overlapping stone effect by using a different type of concrete blocks that are designed to lock together. To create this look, simply stack the blocks on top of each other, alternating the color and/or alignment of each row. With some styles you may also be able to allow some of the blocks to protrude slightly beyond the face of the wall. With this type of block you may also be able to experiment with different block sizes and shapes to create a unique look.
Note, however, that interlocking blocks are generally designed for construction without the use of mortar or other strengthening materials such as rebar. This allows for a relatively quick and simple construction project. However, without mortar or rebar, the wall is unlikely to be strong enough for most retaining wall applications, especially those designed to hold back sloping earth or situations where conditions may call for a stronger construction method.
Stacked Blocks
When most people think of blocks, they picture the small, rectangular block used in building construction. However, concrete blocks come in many different shapes and sizes, and some may be suitable for building stacked walls.
Stacked blocks can also be used to build retaining walls of various shapes, including curving walls or walls with sharp angles. However, like interlocking block walls, this style of wall may not be strong enough to hold back a significant amount of earth, making it only suitable for retaining walls of very modest height.
Different Types of Concrete Blocks
Concrete retaining wall blocks are a versatile construction material used for various applications. Below are some types of concrete wall blocks that are available for you to use:
Stacked Blocks
When most people think of blocks, they picture the small, rectangular block used in building construction. However, concrete blocks come in many different shapes and sizes, and some may be suitable for building stacked walls.
Stacked blocks can also be used to build retaining walls of various shapes, including curving walls or walls with sharp angles. However, like interlocking block walls, this style of wall may not be strong enough to hold back a significant amount of earth, making it only suitable for retaining walls of very modest height.
Cinder Blocks
Cinder blocks are a type of retaining wall block that is made from concrete and coal ash. They are commonly used to construct walls, foundations, and other structures, including retaining walls. Some of the advantages of cinder blocks is that they are inexpensive, they can be reinforced with steel rebar, and they’re very strong and durable.
Cinder blocks can also be easy to work with. They are generally stacked and sealed with mortar, which makes them a popular choice for masonry projects. Cinder blocks are typically less expensive than other construction materials such as bricks or stones. As a result, they are often used in budget-conscious construction projects.
While cinder blocks have many benefits, it is important to note that they are not suitable for all applications. For example, they are not typically used in load-bearing walls because they are relatively lightweight.
In addition, cinder blocks can be susceptible to water damage if they are not properly sealed or protected from the elements. As a result, they may not be the best choice for projects in wet or humid climates, or where there are significant drainage issues. Despite these limitations, cinder blocks remain popular for retaining walls and other construction projects due to their affordability and durability.
How Much Does It Cost to Build a Retaining Wall?
The average cost of creating a retaining wall is $20 to $50 per square foot, which can total as much as $2000 to $5000. However, if you want a larger and more elaborate design, the cost can be as high as $10,000 to $15,000. To get a more accurate estimate of the cost of your project, it’s best to discuss this with your contractor.
How Deep Should a Block Retaining Wall Be?
A block retaining wall’s depth should normally be about one-eighth of the height of the wall. This ensures that the wall is stable and can withstand the lateral pressure from the soil or debris behind it. You will likely need to use a stronger material such as concrete for taller walls, or you may be able to use landscape retaining wall blocks for modest sized projects.
For retaining walls more than 4 feet in height you will need an engineer to design the wall. Your design will specify details such as required depth of the wall and backfill details. A design by a certified engineer is typically required by local building codes for walls exceeding 4 feet in height.
Do I Need a Concrete Footing for a Retaining Wall?
No, you do not necessarily need a concrete footing for a retaining wall, depending on the type of wall chosen and the specific design. The footing is not a structural component but acts as a leveling pad for the wall, preventing it from sinking into the soil. It’s important to ensure that the footing is level, so that the wall will be stable and long-lasting. You can use a spirit level or string line to check that the footing is level.
Professional Engineering Retaining Wall Design – Fast and Affordable
Whichever material you choose for your retaining wall, keep in mind that most local building codes require an engineering design for any retaining wall of 4 feet or more in height. And even for shorter walls, a design from a trained structural engineer is highly recommended to insure the security and longevity of your wall.
We can provide a certified engineer design for you within 24 hours (M-F) for just $350. Submit your Design Request here, or contact us if you have any questions or unique requirements.
