Retaining Wall 101: The Basics of Design and Construction

A retaining wall with a steps in the center of it

Ever wondered how to transform a sloping yard into a usable outdoor living space? Are you looking for a way to prevent soil erosion on your property?

Look no further!

In this blog post, we’ll guide you through the basics of retaining wall installation and design.

By the end of this post, you’ll have a solid understanding of the different types of retaining walls, their purposes, and how to construct them.

The Basics Of Retaining Walls

A retaining wall behind a fire pit with seats

Retaining walls are structures designed to hold back soil, creating flat, usable spaces in sloping areas.

They also help prevent soil erosion by managing the flow of water on your property.

Retaining walls can be built using various materials, such as concrete blocks, wood, and natural stone, allowing you to choose the perfect design to complement your outdoor spaces.

Freestanding Walls vs. Retaining Walls

While both types of walls can enhance your property, there are key differences between freestanding walls and retaining walls.

Freestanding walls are decorative structures that can define spaces, create privacy, or act as barriers.

A small freestanding wall for sitting next to a firepit.

In contrast, retaining walls are specifically designed to support and retain soil behind them, providing functional benefits like preventing erosion and creating flat areas on sloping ground.

A retaining wall in front of a wooden fence

When You Need A Retaining Wall

The need for a freestanding wall or a retaining wall largely depends on whether a home is situated on flat or sloping ground.

Freestanding walls are more suitable for flat terrain and are often used to separate landscapes into distinct areas, adding visual appeal and breaking up open spaces in your yard.

On the other hand, retaining walls are necessary for sloping grounds, as they provide structural support by using footings to secure the wall in place and effectively retain soil and stop erosion.

Structural vs. Non-Structural Retaining Walls

Retaining walls can also be categorized into two types: structural and non-structural.

Structural retaining walls are built to withstand heavy loads and provide significant support to the soil behind them.

A structural retaining wall that is holding back a slope of rocks

Structural walls are typically over 2 feet tall and are designed to support embankments and create additional horizontal space.

Examples of this include cutting into a slope to accommodate a driveway or filling in an area to support a patio on a steeply sloped property.

Non-structural retaining walls, on the other hand, are designed for lighter loads and mostly serve decorative purposes.

A non-structural retaining wall in the foreground, with a structural retaining wall in the background

This includes smaller landscape elements like grill islands, planters, or garden walls under 2 feet in height.

What Is The Purpose Of A Retaining Wall?

A retaining wall enhances this outdoor living space.

A retaining wall serves multiple purposes, such as:

  • Creating flat, usable spaces out of the sloping ground: This is by far the primary benefit of installing a retaining wall. By holding back soil and creating level areas, retaining walls enable homeowners to maximize the flat, usable space in their yards. The increased usable area can be used to create gardens, patios, or play areas. This not only increases the functionality of the property but can also improve its overall value.

  • Preventing soil erosion: Retaining walls act as a barrier against soil movement, helping to stabilize sloping landscapes and reduce the risk of erosion caused by rain, wind, or other environmental factors. This is particularly important for properties located on hillsides or areas with loose soil.
Retaining walls surround and elevate this pergola structure
  • Managing water drainage on your property: Properly designed retaining walls can help control water runoff and prevent water pooling behind the wall. This is achieved by incorporating freely draining backfill materials and drainage systems, such as weep holes or perforated pipes, which allow water to flow through or around the wall, reducing the pressure on the structure and preventing water-related damage.

  • Enhancing the aesthetic appeal of your outdoor spaces: Retaining walls can be designed and constructed using a variety of materials, such as natural stone, wood, or concrete blocks, allowing homeowners to choose a style that complements their home’s architecture and landscape design. In addition, retaining walls can be used to create terraced gardens, stunning patios, or other visually appealing features that enhance the overall appearance of the property.

What Materials Are Used To Construct A Retaining Wall?

A retaining wall under construction with earthmover visible

There is a wide variety of retaining wall materials available, including:

  • Concrete retaining wall blocks
  • Wood retaining walls (pressure-treated wood or railroad ties)*
  • Natural stone (e.g., fieldstone or flagstone)
  • Poured concrete
  • Large retaining wall blocks (for taller walls)

*Note: Wood is an excellent option for non-load-bearing retaining walls. However, we recommend building a retaining wall out of stone or concrete blocks if it will be load-bearing.

Each material has its unique characteristics, so choose one that best fits your needs, local building codes, and design preferences.

That being said, retaining walls are most commonly constructed using three materials:

  • CMU (Concrete Masonry Unit, often referred to as cinder block)

  • PIP, or “poured-in-place” walls

  • Keystone block (interlocking blocks)

The construction method depends entirely on the chosen material.

CMU walls use a combination of poured concrete, cinderblocks, and rebar. This is the most expensive retaining wall construction method. It is also highly structural, meaning that while it functions well as a retaining wall, it is not aesthetically attractive. If used for a residence, CMU walls are typically finished with stucco or some other type of facing to make them more attractive.

PIP, or “poured-in-place” walls, use poured concrete and rebar to create the retaining wall. Similar to CMU walls, PIP walls are highly structural in appearance and will typically be finished with stucco or stone veneer in order to make them more attractive. PIP walls are the second most expensive type of retaining wall construction method after CMU.

Keystone block walls use interlocking blocks, often in combination with pins and adhesive, to create a retaining wall. This is the most cost-effective retaining wall construction method and the most popular for residential purposes.

Here at Grand Design Landscape, we pride ourselves on using premium Belgard retaining wall block systems to construct our keystone-block-style retaining walls.

How Much Does It Cost To Construct A Retaining Wall?

A retaining wall under construction with snow visible on the ground.

The retaining wall cost depends on various factors, such as:

  • The size and height of the wall
  • The chosen wall materials
  • The complexity of the retaining wall design
  • The need for professional installation or DIY
retaining wall in front of fence

The best way to get an accurate estimate for your retaining wall cost is to consult with a professional or research material and labor costs in your area.

Grand Design Landscape offers a standard retaining wall installation that starts at $5K. This includes a 20-foot-long wall with a height of 2 feet.

You can view more details about our tiers of retaining wall installations and pricing here.

Do You Need A Permit For A Retaining Wall?

A space being prepared for a retaining wall installation

Building permits may be required for retaining walls, depending on their height, location, and local building codes.

Always check with your local authorities before beginning any construction project.

You can view Washoe County’s building permit requirements for retaining walls in Reno, Nevada here.

Factors to Consider When Constructing A Retaining Wall

A natural stone retaining wall in front of a house

When designing and building a retaining wall, keep these essential factors in mind:

  • Support: Ensure the wall can withstand the pressure from the soil it retains by incorporating step-back construction, buried footings, steel reinforcement, cantilevered design, and tie-backs for added strength and stability.

  • Foundation: Build a strong, stable base with proper drainage, including a buried structural footing, to prevent wall failure.

  • Backfill: Use appropriate backfill materials, such as crushed stone, gravel, or sand, to enhance drainage and reduce pressure on the wall. A geogrid mesh may also be required for higher walls or specific site situations.*

  • Drainage: Install drainage pipes or use permeable materials to prevent water buildup behind the wall and maintain structural integrity.

*Note: A retaining wall is only as good as the backfill materials behind it. Water compacts soil after it rains, and if your retaining wall doesn’t have correctly installed draining materials behind it, the compacted soil will put increasing pressure on the wall until it collapses.

The primary reason most retaining walls fail is due to a lack of proper drainage!

Tips For DIY Retaining Wall Design and Construction

A long retaining wall next to a wooden fence

If you’re considering a DIY retaining wall project, follow these tips for success:

  • If the wall is over 3 feet, seriously consider hiring a professional. Retaining walls over 3 feet high may require additional support features, such as a geogrid mesh or drainage tile to prevent water buildup.

  • Choose a material you can easily manage and that complements your architectural style. Keystone block construction is less complicated than poured-in-place construction.

  • Partially bury your first row of blocks for stability (this is called a “buried structural footing”).

  • Make sure your first row is perfectly level, or the whole wall will be unlevel.

  • Be sure to make retaining wall construction the first step in your outdoor living space plans. Retaining wall construction is the most invasive type of project you can do in your yard due to the large amount of soil that must be moved to create it. So any preexisting plantings or other landscape features must be moved, or they could be damaged during the retaining wall construction process.

Grand Design Landscape Can Design And Build Your Unique Retaining Wall

A home with blue accents has a retaining wall for their front yard

Now that you have a better understanding of retaining walls, their purposes, and the factors to consider when constructing one, you may feel ready to take on your project.

Remember, retaining walls not only serve functional purposes but can also enhance the beauty of your outdoor space.

At Grand Design Landscape, we can help you design and build the perfect retaining wall for your property.

Our team of experienced professionals will guide you through the entire process, ensuring that your retaining wall meets all requirements and complements your outdoor spaces.

Don’t wait any longer to transform your sloping yard into a beautiful and functional area – fill out our contact form today or give us a call!

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