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What is an Interlocking Retaining Wall?

C. Mitchell
C. Mitchell

An interlocking retaining wall is an element of landscaping that can be both functional and aesthetic.  In function, it acts as a barrier for water run-off, usually down a hill.  In this way, the wall promotes even soil moisture, and prevents erosion.

An interlocking retaining wall is called “interlocking” because it is typically made of stones or bricks set in a variegated, or interlocked, pattern.  This is in contrast to retaining walls that are made up of a single layer of stones, or are built of one element without a pattern.   The interlocking nature of the wall makes it strong and long-lasting, and usually also attractive. 

Blocks are set in an interlocking manner to create a retaining wall.
Blocks are set in an interlocking manner to create a retaining wall.

Backyards or gardens that are set on a hill can often be improved with the addition of an interlocking retaining wall.  Typically on a hill, water runs from the top the bottom, resulting in very moist conditions at the bottom of the hill, but relatively weak soil moisture at the top.  In rainy climates or when water is plentiful, hilly conditions can lead to soil erosion over time.  The nutrients and strength of the soil at the top of the hill are often pushed by water to the bottom.  Plants at the top of the hill suffer from poor soil, while plants at the bottom can be weakened by over watering.

A common solution to the problem of moisture distribution is a retaining wall. The primary retaining wall function is to act as a barrier for moisture in the soil.  In an interlocking retaining wall, bricks or stones are set deep in the soil midway down the hill, and are built up in an interlocking fashion several feet above the surface.  The size of an interlocking retaining wall varies with the setting, but typically the walls extend the length of the yard or garden.

The retaining wall stops moisture and nutrients from traveling all the way down the hill.  In a sense, it breaks the hill up, creating two relatively flat surfaces, or terraces, with more uniform ground elevation.  In this way, water will hit each terrace in a more even fashion, which helps plants grow more optimally and keeps the soil from moving around. 

Retaining walls generally have an aesthetic appeal, as well.  The terraced look can give a yard or garden an air of sophistication, and has become a common aspect of garden improvement and backyard improvement.  Even where erosion control is not a concern, landscape architects and those interested in landscape design often use interlocking retaining walls to give the impression of varying yard levels.  Sometimes a whole wall system will be added to a yard to separate areas and designate different garden areas.

An interlocking retaining wall is relatively simple to build.  Many home improvement stores sell bricks and stones that have been specially created to interlock with each other, and can make creating an interlocking retaining wall a snap.  Ordinary bricks and rocks can also be fashioned into an interlocking pattern, though these may need mortar or other adhesive to join. 

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    • Blocks are set in an interlocking manner to create a retaining wall.
      By: dbvirago
      Blocks are set in an interlocking manner to create a retaining wall.