How to Build A Concrete Retaining Wall (in 9 Simple Steps)

Building a concrete retaining wall can seem daunting, but it’s a project that can be tackled with some planning and the right steps.

Key Takeaways

  • Concrete retaining walls provide structural support and prevent soil erosion.
  • Proper planning and design are crucial for a durable wall.
  • The construction process involves excavation, base preparation, building forms, adding reinforcement, pouring concrete, and finishing.

How to Build A Concrete Retaining Wall

How to Build A Concrete Retaining Wall

1. Understanding the Basics

A concrete retaining wall isn’t just an outdoor structure; it’s like a strong, dependable friend keeping the soil in your landscape from sliding or eroding away. 

This sturdy wall does a fantastic job at battling against erosion, helping to keep your garden soil where it should be, and maintaining the shape and integrity of your landscaping.

It serves a crucial practical purpose, and spruces up your garden with a touch of neatness and an architectural edge.

Plus, it’s a sturdy long-term partner for any garden, resisting the ups and downs of weather over the years without complaining.

All in all, a concrete retaining wall is a smart, durable investment for any homeowner looking to enhance their outdoor space..

2. Design Considerations

When planning how to build a concrete retaining wall, you should not underestimate the importance of design considerations.

The wall’s shape, size, and placement are critical for ensuring not only its effectiveness but also its stability and longevity.

The shape must be designed to resist the lateral pressure of soil it will be holding back, which often requires a slight lean into the retained earth.

Size is also key; for taller walls, thicker concrete and a more substantial foundation are necessary. 

Placement is crucial to avoid underground utilities and to ensure proper drainage, which can otherwise lead to hydrostatic pressure buildup against the wall.

3. Site Preparation

This involves the meticulous removal of all vegetation like bushes, trees, and grasses as well as the stripping away of the topsoil, which is often rich in organic material and can be repurposed in other landscaping activities. 

It’s essential that the ground is cleared down to the subsoil, which is typically more compact and better suited as a foundational base for construction. 

The removal process prevents organic decay from compromising the wall’s integrity, and creates a clear and level space for laying the wall’s foundation.

4. Materials and Tools Required

When setting out to build a concrete retaining wall, you’ll need specific materials ready before you start. 

These include:

Concrete BlocksThe core building material for your wall
RebarLong, steel bars that reinforce the strength of the concrete blocks
GravelUsed for drainage behind the wall
SandMixed with cement to create the mortar

As for tools, make sure to have:

TampersTo compact the gravel and soil.
LevelsEssential for making sure your wall is even and straight.
SawsNecessary for cutting your rebar or concrete blocks to the correct size.

5. Excavating and Leveling the Base

Once you’ve planned where your concrete retaining wall will go, it’s time to roll up your sleeves for some digging. 

Your goal for this step is to remove dirt and create a flat, solid ground where the wall will sit. 

Here’s how to tackle this:

  1. Firstly mark the ground using string and stakes to outline where the wall will be. Ensure you measure twice to avoid any mistakes.
  1. Grab a shovel or use machinery for larger projects to excavate the soil within the marked area. You’ll want to go down deep enough to fit the base material and the first layer of your wall blocks.
  1. After digging, you’ll probably find some spots are higher or lower. Smooth these out with a rake or hand tools until you’ve got a level surface.
  1. Firm up the base by compacting the soil. You can use a hand tamper or rent a mechanical one, especially if your project is large.
  1. Shovel in a layer of gravel to promote drainage and add stability. Spread it uniformly across the base area and then make it level just like you did with the soil.
  1. Go over the gravel with your tamper to make a really firm base that won’t settle over time.

6. Building Forms and Adding Reinforcement

You should start by delineating the area where the wall will be constructed and excavate as necessary. 

Then, construct sturdy wooden frames—these forms will hold the concrete in place as it sets. 

Ensure that the forms are securely braced and leveled to avoid any shifts that could compromise the wall’s integrity.

Once the forms are in place, it’s time to add reinforcement to bolster the structure. This typically involves installing rebar (steel bars) inside the forms before pouring the concrete.

The rebar should be arranged in a grid pattern and tied together at the intersections for enhanced strength.

This metal reinforcement is vital as it helps the wall withstand pressures, like soil movement and water flow, that could otherwise lead to cracks or even a collapse.

Make certain the rebar is adequately covered with concrete during the pour to prevent future rusting and maintain the wall’s strength.

7. Pouring the Footings and Wall

You should begin by preparing the area where the concrete will be poured, ensuring that the forms are sturdy and correctly positioned.

When mixing the concrete, follow the manufacturer’s instructions precisely for water and concrete mix ratio to ensure optimal strength.

As you pour the concrete into the footings, be careful to fill every corner and avoid leaving any voids.

A technique called ‘tamping’ can be used to settle the concrete and eliminate air pockets, which can weaken the structure.

Once the footings are set, the concrete wall must be poured incrementally, layer by layer, continually checking for level and straightness to maintain the wall’s integrity.

Remember to cure the concrete properly by keeping it moist for at least a week, which helps prevent cracks and increases the overall strength of the retaining wall.

8. Backfilling and Drainage

Backfilling the space behind your concrete retaining wall is essential for its stability and longevity.

Properly backfilling with gravel allows water to drain easily, preventing pressure buildup that could weaken or damage the wall. 

Moreover, installing a drainage pipe, typically at the base of the wall, ensures that any water that does accumulate can be quickly diverted away, further protecting your structure from water damage and soil erosion. 

Simple maintenance of these drainage systems can save a lot of trouble in the future, which makes your retaining wall both sturdy and durable.

9. Finishing Touches

After your concrete retaining wall has set, it’s time for the finishing touches. This is when you carefully remove the forms without disturbing the concrete.

Let the concrete cure properly, which means keeping it moist and allowing it to strengthen over time—usually a week or more, depending on the weather and size of the wall.

Finally, add any finishes you desire, such as painting or sealing, to protect your wall and enhance its appearance. 

These final steps are crucial for ensuring the longevity and effectiveness of your new retaining wall.

You can watch the video below to better understand the process:

How thick should a concrete retaining wall be?

The thickness of a concrete retaining wall typically depends on the wall’s height and the soil pressure it needs to withstand.

For most residential situations, a wall that’s up to about 4 feet tall should have a minimum thickness of 6 inches. 

As the wall gets higher, the thickness should increase for added strength and stability. For walls above 4 feet, consulting a structural engineer is recommended.

Find our guides on what are different types of concrete flooring, concrete flooring pros and cons, and concrete flooring images.

How do you mix concrete for a retaining wall?

Usually, you’ll need a wheelbarrow for mixing; pour the dry mix into it. 

Then, add water gradually as you mix with a shovel; the consistency should be like peanut butter, not too wet or dry. 

If it’s too dry, add more water, if too wet, add more mix. Once you have a homogenous mixture, it’s ready. 

What kind of concrete do you use for a retaining wall?

You should typically use a strong, durable concrete mix with a strength rating of at least 3,000 psi (pounds per square inch). 

It’s also advisable to utilize a mix containing coarse aggregate, which improves stability and drainage. 

Certain projects might require even higher strength mixtures or additional reinforcement, depending on the wall’s height and the soil pressure it must withstand. 

Final Thoughts

Building a concrete retaining wall is an achievable project that requires careful planning, the right materials, and a bit of muscle.

If this task seems daunting, or you want to ensure it’s done by professionals, don’t hesitate to reach out for our expert concrete services. 

References:

Concrete network

Family handyman

Buffalo NY Concrete Contractor

Buffalo NY Concrete Contractor

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