Retaining walls are a versatile, functional landscaping element used on sites where terrain is naturally very sloped. Landscaping retaining walls serve a variety of purposes:
- to stabilize naturally unstable sloped ground
- to hold back, or retain, soil that has been dug out to flatten a naturally sloped terrain
- to remove hills and create usable, flat yard space
- to create beautiful tiered terraces for curb appeal
- shorter retaining walls are often built to contain flower beds or vegetable gardens
- to correct drainage problems
- to proactively control erosion
Planning a landscaping retaining wall
Retaining walls are used to stabilize unstable hills by controlling drainage and adding reinforcement structure to prevent the soil and earth from falling and sliding. Some things to consider if landscaping retaining walls are part of your vision:
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Base
As with all building projects, starting with a solid base is the most important step in ensuring longevity of a project. Retaining walls on a slope require a strong base of compacted soil and other materials below ground level to support the wall. They must be built on solid ground with proper drainage.
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Cut or Backfill
There are basically two ways to construct retaining walls. One method is to cut into the hillside and remove the soil and material from the lower part of the slope, building the wall in what was the upper middle part of the slope. The other basic method is to build the wall at the bottom of the slope and fill in the space behind the wall until it is level with the top of the hill.
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Gravity or Reinforcement
Depending on site conditions, some reinforcement walls can be built to support themselves. The angle at which they are built into the hill (called setback) and the weight of the wall allow gravity to support the wall and keep the soil stable. Reinforcement is usually needed in walls built on clay soil, because water that absorbs into the soil builds pressure behind the wall. Reinforcement is also needed on landscaping retaining walls that will have driveways, patios, or pools built on top.
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Drainage
Improper drainage can lead to bulging or cracking in the retaining wall, which may or may not be repairable in the future. At Unlimited Drilling, we have repaired and rebuilt sloppy and carelessly built foundations and retaining walls, so when we are hired as builders, we plan for quality and longevity. We take the extra steps to ensure our work will solve your landscaping problems, not create more! Proper water control behind the wall is essential in our process. Test your soil before planning a retaining wall. Sandy soil drains better than clay. Organic soils should only be used to finish the top of a retaining wall, never to fill.
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Height
It’s important to keep in mind that the height of a wall will determine the load of soil it can bear. Wall heights should be determined based on the topography of each site.
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Material
Landscaping retaining walls can be a beautiful functional design element in landscaping projects. They can be built from a number of materials with varying lifespans. They can be accented and finished on the outside with various decorative materials. Most commonly, retaining walls are built from wood or concrete. However, the type of retaining wall that can be built in a terrain depends on the terrain itself. Extreme slope can make concrete walls cost prohibitive. Wood walls can wear and may require more maintenance over time.
