How to Build a Retaining Wall?

How to Build a Retaining Wall?

Consider sprucing up your yard? A retaining wall may just be the perfect solution for you! These walls not only afford a good containment that helps ensure that your soil does not drip down the slope, but also can act as an aesthetic structure to improve the appearance of your compound. If you’re an excited and eager do-it-yourselfer or if you’re simply still searching for the right professionals to talk to, then I’ll gladly explain it to you in detailed, friendly layman’s terms. Alright, let it begin, and let’s make your new wall not only beautiful but durable as well throughout the coming years.

What’s a Retaining Wall?

A retaining wall is quite simply a wall which is built to support soil and create flat terrains from areas that contain slopes that are steep. These walls are usually constructed using concrete, stones, brick, or timber depending on the landscape design and the owner’s preferred style, height and design of the walls can also be determined by the available space.

Why Build a Retaining Wall?

  • Prevent Soil Erosion: That is why retaining walls are so important, as they help prevent soil from being washed away when applied on an incline. They also prevent your garden or yard from slipping and eroding, preserving your plants and hardscapes.

  • Create Level Areas: If your yard has uneven ground, a retaining wall can help grade those areas to be favorable for planting flowers, make a garden, or to build a sitting area. It can considerably increase the functionality of your space.

  • Enhance Aesthetic Appeal: Retaining walls can be just beyond ordinary structures; they can be aesthetically appealing structures in your home and landscape. It comes in numerous types of material and cuttings that it can bring a playful touch to one’s outdoor setting.

  • Increase Property Value: A good built retaining wall provides value … It also nurtures the physical appearance of the home to ensure that if by any chance you plan on selling your property, you might attract better clients.

  • Control Water Drainage: Retaining walls can help manage water flow around your property, directing runoff to appropriate drainage areas and reducing the risk of water pooling in unwanted spots.

  • DIY Satisfaction: Building a retaining wall can be a fulfilling project for those who enjoy DIY tasks. With the right tools and resources, it’s an achievable endeavour that lets you personalise your landscape while gaining practical experience.

Step-by-Step Guide to Building a Retaining Wall

Step 1: Planning and Preparation

1. Determine Size and Location: Depending on the purpose of the retaining wall you need to choose it based on what the wall will be specifically used for; whether for control of soil erosion or for creating several planting levels.

2. Decide Height: Make sure to take height measurement of how high you wish the wall to be. Remember that walls with height exceeding 4ft might require a building permit and might also need an engineer plan – consult with your local officials.

3. Mark Utility Lines-Safety First: A good option is to contact local utilities to get information on where it is possible to locate any cables, pipes, or lines for the possible damaging during construction.

4. Gather Materials and Tools

Materials Needed:

  • Granular A (For the base)

  • Retaining wall blocks (it is preferred that they can interlock).

  • PVC perforated pipe to be used for drainages in order to avoid accumulation of water on the ground.

  • Landscape fabric, this is used to avoid transfer of soils from the different areas of the garden.

Essential Tools:

  • Tamper (manual or powered)

  • Shovel

  • Masonry saw (for cutting block, in case it is needed)

Step 2: Building the Foundation

1. Excavate the Base

  • Digging the Trench: Dig a ditch that is with dimensions of approximately 24 inches wide as well as 6-8 inches deep. It should be extend at least 6 inches beyond the front of all intended wall blocks for stability purpose.

  • Levelling the Trench: Place a long 2x4 under a level on top of the trench bottom to check that the bottom is level throughout its length.

2. Compact the Base Material

  • Gravel Foundation: Place 4-6 inches of compactable gravel in the trench and then compact it by using the tamper. It is important when developing a stable base.

  • Add a Sand Levelling Layer-Screeding Sand: Place a layer of sand of 1 inch thickness on the worked out gravel and level it using a screed. This will enable you to level the first course of blocks.

Step 3: Installing Proper Drainage

  • Lay a Drainage Pipe - Prevent Water Buildup: To direct water away from the wall, install a perforated drainage pipe behind it. Make sure to wrap the pipe in a drain sleeve to reduce the chances of clogging.

  • Backfill with Gravel - Continuous Drainage: As you build up more layers, backfill each one with gravel around the drainage pipe. This setup allows water to flow freely, relieving hydrostatic pressure and safeguarding the wall's integrity.

Step 4: Stacking and Finishing

  • Stagger the Blocks - Building Stability: When adding more rows of blocks, stagger each new layer over the joints of the layer beneath. This method enhances overall stability and strength, which is essential for taller walls.

  • Add Capstones - Final Touches: After reaching your desired height, finish the wall with capstones for a refined look. Use landscape adhesive to secure them, ensuring they slightly overhang for an attractive edge.

Affordable Retaining Wall Options

When planning a retaining wall project, it's important to find budget-friendly materials. Here are some economical choices:

  • Interlocking Concrete Blocks: These are favoured for their easy installation and versatility. Available in various sizes and shapes, they allow for custom designs without needing mortar. They are also generally more affordable than stone or poured concrete walls.

  • Treated Timber: For smaller walls (under 4 feet), treated timber is a cost-effective option. It offers a natural look that complements garden landscapes. However, timber may not be as durable as concrete or stone, particularly in high-moisture areas.

  • Gabion Walls: Constructed from wire cages filled with stones or gravel, gabion walls are sturdy and simple to build. They are ideal for areas where drainage is important and can provide a unique, modern appearance.

  • No Fines Concrete (NFC): This lightweight concrete mix is a great choice for anyone looking for a material that is easy to work with and offers good drainage. It’s particularly suitable for DIY enthusiasts since it’s easier to mix and pour compared to traditional concrete.

Cost-Saving Tips for Retaining Walls

Constructing a retaining wall can be a major expense, but there are several strategies to cut costs without compromising on quality:

  • DIY Installation: Labor costs can significantly increase the overall expense of building a retaining wall. For smaller walls under 4 feet, taking a DIY approach can save you hundreds or even thousands of dollars​.

  • Use Local Materials: Choose materials that are easily accessible in your area, such as local stone or recycled concrete blocks. This can help lower transportation costs​.

  • Plan for Proper Drainage: Although drainage pipes and gravel may add to your initial costs, they are essential for preventing water accumulation and soil erosion, which can lead to expensive repairs later on​.

  • Rent Equipment: Instead of buying costly tools like a masonry saw or gas-powered tamper, consider renting them from a home improvement store for a much lower price​.

Size and Height of Your Wall

The dimensions and height of your retaining wall are vital for the design and structural stability of the project:

  • Small Walls (Under 3 Feet): These walls can typically be constructed without professional assistance or permits, making them perfect for DIY projects. They work well for garden beds, flower terraces, and minor slopes​.

  • Medium Walls (3 to 4 Feet): Walls in this height range may need extra stability measures, such as geogrids or additional compacted backfill. Depending on local regulations, a permit might be necessary if the wall is near property lines or public areas.

  • Tall Walls (Over 4 Feet): Generally, walls taller than 4 feet will require a structural engineer's plan and a construction permit. These walls need a deeper foundation, effective drainage systems, and often require materials like reinforced concrete for added stability.

Why Do Retaining Walls Need Drainage?

Drainage is essential for the durability and stability of a retaining wall. Without adequate drainage, water can accumulate behind the wall, leading to hydrostatic pressure that may cause the wall to shift, bulge, or even collapse. Here’s why drainage is important:

  • Prevents Soil Saturation: Excess water can transform the soil behind the wall into a heavy, dense mass that exerts pressure on the structure. Proper drainage helps channel this water away.

  • Reduces Erosion: Water that collects behind a wall can erode the soil, compromising the foundation. Installing a drainage pipe along with gravel backfill helps prevent this problem.

  • Increases Wall Lifespan: A well-drained wall will retain its shape and integrity for many years, minimising the need for repairs.

Can I Build a Retaining Wall by Myself?

  • Skills Needed- Basic Construction Skills: It's important to be familiar with basic tools like shovels, levels, and rubber mallets. You should also feel comfortable measuring and cutting materials as necessary.

  • Masonry Knowledge: A solid understanding of how to stack blocks or stones, ensuring they are level, and applying the right bonding techniques (if needed) is vital for the wall's stability.

  • Soil and Drainage Understanding: Knowing about different soil types and drainage principles will aid in designing the wall effectively. Proper drainage is essential to prevent water accumulation behind the wall, which could lead to structural failure.

  • Problem-Solving Skills: Be ready to address any issues that may come up during construction, such as uneven ground or unforeseen soil conditions.

  • Time Commitment- Planning Phase: Before starting, set aside time for planning and gathering materials. This process might take a few days, especially if you need to check with local authorities for permits.

  • Construction Time: The time it takes to build a retaining wall can vary based on its length, height, and complexity, ranging from a weekend to several days. Factors that can affect this include:

  • Excavation: Digging the trench for the foundation can be labour-intensive, particularly if you run into rocky or compacted soil.

  • Laying Blocks: The process of laying the blocks or stones requires careful attention to detail and may take longer than anticipated.

  • Backfilling and Compaction: Properly backfilling and compacting the soil behind the wall is crucial for stability and may take extra time.

  • Weather Considerations: Keep an eye on the weather, as rain or extreme temperatures can disrupt your work schedule. It's best to work in dry conditions, especially when using concrete or mortar.

  • Safety: Always prioritise safety by wearing the right protective gear, such as gloves and safety glasses. If you're handling heavy materials, consider using proper lifting techniques or getting assistance to prevent injury.

Are There Any Laws on Retaining Walls?

Building codes and regulations often dictate the construction of retaining walls, especially when they exceed a certain height:

  • Permit Requirements: Most municipalities require a permit for walls taller than 4 feet due to the increased risk of structural failure.

  • Property Line Considerations: If the wall is close to property boundaries, you may need to consult with neighbours and follow setback requirements.

  • Inspection and Engineering: Larger retaining walls may need to be inspected during construction and after completion to ensure they meet safety standards.

For more Information, check the National Construction Code

What’s the Point in Using an Expert for a Retaining Wall?

While it’s possible to build retaining walls on your own, there are specific scenarios where hiring a professional is advantageous:

  • Complex Designs: If your wall features curves, tiers, or is situated on a steep slope, a professional can ensure that the design and installation are structurally sound.

  • Structural Integrity: Experts can assess soil conditions and apply appropriate engineering techniques, such as geogrids or reinforced concrete, to create walls that can endure high pressure.

  • Permits and Regulations: Professionals are knowledgeable about local building codes and can manage permit applications and inspections for taller walls.

  • Long-Term Savings: Although the initial cost may be higher, a wall built by a professional typically lasts longer and requires fewer repairs over time.

Ready To Start Your Construction Project?

Constructing a retaining wall can be a rewarding project that enhances your outdoor area. For those interested in expanding their knowledge or pursuing a career in construction, consider enrolling in courses like the Advanced Diploma of Building Surveying: Building Surveyor Course NSW, CPC50220 - Diploma of Building and Construction (Building) or Certificate IV in Building and Construction through theBuilding Institute NSW.

Visit Building Institute NSW today to enhance Your Construction Knowledge!

FAQ

  1. Can you build a retaining wall on a slope?

Answer: Yes, retaining walls are often built on slopes to create flat areas or to prevent soil erosion. When designing and constructing these walls, it's important to consider additional factors for slope stability and drainage.


  1. Are there any environmentally friendly retaining wall options?

Answer: Absolutely, there are several eco-friendly options for retaining walls. Using recycled materials, such as reclaimed concrete or salvaged stones, can be beneficial for the environment. Additionally, incorporating effective drainage and erosion control measures can help minimize the environmental impact of the retaining wall.

  1. Which type of retaining wall is the most budget-friendly?

Answer: The most cost-effective type of retaining wall is typically made from wood or timber, with masonry being the next most affordable choice.

  1. Is it possible to build a retaining wall without a footing?

Answer: Not all retaining walls require a footing. For instance, interlocking retaining walls can be built without one. Factors such as wall height, soil conditions, and slope will influence whether a footing is necessary.

  1. How deep does a retaining wall have to go?

Answer: You should dig a trench that is about 12 inches deep and 24 inches wide for the length of the wall. Make sure to compact the subgrade soil well and line the excavated area with landscape fabric. Fill the trench with 1.5-inch processed gravel or 3/4-inch crusher run base material, compacting it firmly in 2-3 inch layers until the base reaches a thickness of 6 inches.

  1. How much does it cost to build a 2-foot retaining wall?

Answer: For a 2-foot-tall vinyl retaining wall, you can expect to pay around $10 per linear foot. If you're considering higher-end materials like steel or natural stone, the cost will be approximately $100 per square foot. For a 2-foot-tall steel retaining wall, the price can go up to $200 per linear foot.