Ask a Designer: Retaining Wall Options

Retaining walls can be used as a design feature in landscaping but often, they are included out of necessity.

Most, not necessarily all, landscapes come with grade changes. So, depending on how you want to use the space, you may need to install a retaining wall.

There are a few options for retaining walls, each with unique characteristics and suitability for different situations:

  • Armour stone
  • Structural interlocking system
  • Structural building block system with added face wall units
  • Segmental retaining wall system
  • Dimensional wall

Armour Stone

Armour stone walls refer to large pieces of natural stone rocks, usually granite, limestone, or sandstone. They are irregular shapes and are used in a variety of landscape applications. The stones are uncut and untreated giving them a more rugged natural esthetic. They are often chosen for their appearance, hardiness, and resistance to weathering. When used in retaining walls, they are arranged to interlock somewhat. Some cutting is involved to allow for a tighter fit while still maintaining their natural look. Once built, they are stable and can prevent soil erosion.

Here is one example of a retaining wall along a driveway. As you can see, one property is substantially higher than the other. The old wood wall was replaced with this new armour stone wall.

In this sloped backyard, armour stone walls were created to make use of the slope by turning into a garden at the back of the patio. This was a great way to transform previously unusable space.

Structural Interlocking System

Structural building block system or interlocking wall uses concrete blocks that link together with tongue and grooves to create structure. if the wall needs to be higher, there is also an option to create a setback with this wall type to create extra support. These wall blocks can also be used to create other design elements in the landscape like pillars, seat walls, planters, and steps. The design elements are limited to a rough or chiselled surface.

Some manufacturers now have a block with a smooth finish available. To create an elevated look, a matching concrete coping or a natural stone coping could be used.

Segmental Retaining Wall System

Segmental retaining walls tend to be used more for commercial applications but, depending on the size of the yard and the height necessary, they can be used for residential applications. They are similar to the interlocking retaining wall with their tongue and groove interlocking, but the individual blocks are approximately 4 feet long which gives them a more commercial look. The new smooth options also provide a modern look if that is what you are looking for.

One of the newest trends is a structural building block wall made of concrete backer blocks with grooves on the perimeter to allow for a variety of wall facings to be hung. This new system also easily allows for single or double side walls because the facing can hang on both sides for design elements like a seat wall or address wall. There are several varieties of these systems and they have really elevated the design of retaining walls but have kept the construction “behind the wall” the same.

Dimensional Wall

Lastly, for shorter walls or for support levelling a patio, a dimensional stone can be used. They are essentially stacking blocks that are interlocked and glued together for garden walls or retaining walls under a patio, for instance. They have been commonly used with a “tumbled” look for years and now, sleeker and smoother options are available.

Although I’ve covered the overall design and possible landscaping uses, there are many other details, such as drainage and base to mention a few, that go into choosing the proper retaining wall system for your space. This requires the involvement of a professional landscape contractor who can both educate the property owner as well as install the retaining wall system.



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