Looking to tackle some backyard landscaping and wondering how to build a retaining wall? Well, you can lean on us for advice!  

A well-constructed retaining wall can prevent soil erosion and transform an uneven garden into a visually pleasing, functional space. It’s essential to start with thorough planning by taking the desired location into account and the specific requirements of the area.

Aside from focusing on the aesthetics and functionalities of your retaining wall, keep in mind that some regions may require permits or have specific guidelines on height and construction materials. Ensuring compliance will save potential headaches and ensure the structure’s longevity and safety.

DIY enthusiasts will find that learning how to build a retaining wall can be a rewarding project. Whether you prefer working with concrete blocks, timber, or natural stone, careful consideration of each step will do landscaping design magic for your yard.

So if you are set on exploring the ins and outs of how to make a retaining wall that lasts, you’ve stumbled across the right guide!

Design and Planning

Evaluating Location and Soil Conditions

Assessing the location involves checking the slope, drainage, and potential impact on nearby structures. Inspecting if the slope is not too steep is essential for stability levels.

On top of that, proper drainage plays a pivotal role in preventing water build-up behind the wall. Water accumulation can lead to pressure and, eventually, full-fledged failure.

The first order of business is assessing the soil type, as this significantly impacts the design. Sandy soils drain well but may need reinforcement. Clay soils, on the other hand, easily hold water and exert more pressure on the wall, requiring sturdier construction materials. 

Soil testing can help in understanding the specific requirements and challenges surrounding this step in learning how to build a retaining wall.

Choosing Materials

  • Retaining wall blocks are popular due to their ease of use and versatility. They come in various sizes and can cater to different aesthetic preferences.
  • Wood is another choice, offering a natural look. Nevertheless, it may require specific treatment for longevity. 
  • Concrete sleepers provide a robust and long-lasting option, especially for taller walls. They are heavy and durable but can be more challenging to install.

Your choice of materials heavily depends on the desired wall height and soil conditions. For instance, taller walls or walls retaining heavy clay soils might benefit more from concrete sleepers. For best results, the materials need to align with the design requirements and local regulations. 

Preparing the Foundation

A strong foundation is a key component in the quality of a retaining wall—or anything else on life, for that matter! It involves elaborate excavation and trenching, followed by the engineering of a solid base with proper materials. 

Excavation and Trenching

  • Step 1: Start by marking the area where the retaining wall will be placed. Use stakes and string for seamlessly straight lines.
  • Step 2: Begin excavating with a shovel or spade. Dig out a trench that is slightly wider than the retaining wall blocks. This trench should typically be about 300 mm deep for a standard landscape wall. Furthermore, the trench should be levelled from end to end. Use a spirit level tool to measure and adjust as you go.
  • Step 3: Compact the soil at the bottom of the trench using a hand tamper or a mechanical compactor. This step helps prevent future settling, which could compromise the wall.

Building a Strong Base

Once the trench is ready, it’s time to build a base. 

  • Step 1: Kick this off by adding a layer of coarse gravel. Ideally, this gravel base should be about 100 mm thick.
  • Step 2: Spread the gravel evenly. Whip out your spirit level again to get an accurate reading. Compact the gravel firmly using a hand compactor or mechanical compactor.
  • Step 3: On top of the compacted gravel, add a thin layer of coarse sand. This layer helps with further leveling and stability.

For good measure, check for level once more, making adjustments as necessary. These steps warrant the retaining wall has a stable, level foundation capable of supporting its weight and the pressure from the retained soil.

Constructing the Retaining Wall

And now, the moment you have all been waiting for! Let’s answer the burning question: How do you build a retaining wall? Now that the preparation steps are set into place, we can proceed with the construction of the actual wall. 

Laying the First Course

  • Step 1: Place the first blocks into the trench. You guessed it; you can use a spirit level to verify if each block is level from front to back and side to side. Adjust as needed by adding or removing gravel. Pro tip: Laying the corner units first helps in keeping the wall straight.
  • Step 2: Apply construction adhesive between each block to secure them in place. This prevents shifting and adds strength. Make sure the first course is perfectly aligned, as it sets the stage for the rest of the wall. No one wants a crooked wall, so don’t be afraid to be extra rigorous with the first blocks.

Final Touches and Drainage

Installing Drainage Systems

Before one can say that they have learned how to build a retaining wall like a pro, they will have to go through the ultimate test: drainage system installation! The quality of the drainage system will either make or defeat the purpose of a retaining wall.

  • Step 1: Utilise perforated drainage pipes to channel water away. These should be installed at the base of the wall within a trench.
  • Step 2: Support it by backfilling the area behind the wall with gravel, which allows water to filter through with ease.
  • Step 3: Next, craft a slight slope away from the wall to facilitate water flow. Use a garden hose to test the drainage system. This way, you can gauge if water is flowing correctly from the get-go. 

Capping and Finishing

Finishing touches include capping the top of the wall for a polished appearance. Caps can be attached using a caulking gun and a strong adhesive.

Moreover, consider dolling the wall up with plants and flowers along the base or top to enhance the wall’s appearance. Florals and greenery have the power to brighten up any space. Plus, a splash of flowers and plants is just a beautiful excuse to boost erosion control.

Down the road, remember to regularly inspect and maintain the wall’s integrity. 

a person building a retaining wall

A Summary: How to Build a Retaining Wall

Design and PlanningDesign and planning of a retaining wall are critical to ensure its stability and longevity. Key points include evaluating location and soil conditions, as well as selecting appropriate materials.
Evaluating Location and Soil ConditionsAssessing the location involves checking the slope, drainage, and potential impact on nearby structures. Proper drainage and soil type significantly impact the design.
Choosing MaterialsRetaining wall blocks, wood, and concrete sleepers are popular choices, depending on wall height and soil conditions.
Preparing the FoundationExcavation, trenching, and building a strong base are crucial steps in preparing the foundation of a retaining wall.
Constructing the Retaining WallBuilding the actual wall involves laying the first course, applying construction adhesive, and installing drainage systems.
Final Touches and DrainageInstalling drainage systems, capping, and finishing the wall are important for its appearance and functionality.
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Wall to Wall Reliability

Knowing how to make a retaining wall is one thing, but putting this knowledge into action is another story. When DIY doesn’t fit into your vocabulary, you can put your trust in the experts at Brisbane Landscaping.

From customised designs to durable materials, these landscaping authorities stand by the notion that there is beauty in strength. 

Are you ready to transform your outdoor space with top garden landscaping ideas?

Book our services today!