Types of Landscaping Retaining Walls

Here in Victoria BC, it doesn’t take long to before one spots a retaining wall. Such is the nature of our geography. In this short piece, we will point out and explain the most commonly seen retaining walls used in landscaping here in Victoria.

Block Retaining Wall

This is the standard retaining wall seen commonly in both residential yards and commercial ones. They look like a wall made of large blocks because that’s what they are. These walls most commonly use Allanblocks as that’s the most common supplier in town for this type. They come in large blocks weighing 75 lbs each as well as small blocks, used typically for more gardenscapes than structural purposes. These typically weigh around 25 lbs.

No mortar is used in their construction as they rely purely on gravity and a setback for structural stability. In addition to the setback, meaning the blocks are placed with a slight lean towards the back, the blocks have a groove or lip on their front, giving additional support for the blocks above and preventing them from sliding forward.

These blocks come hollow, which are to be filled with gravel, for increased stability, strength, and weight. They are then sealed at the top with a capstone, to give it a nice clean finished look. Capstones are usually secured with special adhesives but mortar can also be used.

These types of walls are installed for their clean and orderly look.

Boulder Walls

Landscaping projects by Ecoyards, photographed on Saturday, April 18, 2009. (Photo by Dan DeLong)

Boulder walls come in two types: with and without mortar. The walls without mortar is a compromise between the rugged natural look that a boulder walls offer and the orderly refined look of a block retaining wall. However, since mortar is used to seal the joints between the boulders, drainage must be installed in the form of a pipe at the foot of the wall to prevent failure. With a dry stack, which is what a mortar free wall is called, the angular shape of the boulders, their weight, and their size are what holds the wall together. You can see this in action on many beaches and embankments to prevent erosion. Since the joints are not sealed, drainage is not required as water will naturally seep through these cracks.

While both types last decades when properly installed and maintained, these dry stack boulder walls can actually last longer than the block ones as their shape and weight distribution makes the structure naturally stable.

Final Word

In the end when it comes to which type of wall you choose for your landscape, it entirely rests on personal preference of style. Each type of wall gives a different look and feel and their installation offers different challenges. While it may seem easy to place blocks on top of one another, the reality is it’s time consuming to build a stable wall with the pieces and shapes one has.