You always hear about people who are building a retaining wall on their property, but what if they already have a retaining wall?
Can you build a retaining wall in front of an existing one?
As it turns out, yes, you can build a retaining wall in front of an existing one.
The method for doing so is a little different than building a retaining wall from scratch, but it’s not all that complicated.
What are retaining walls?
A retaining wall refers to a wall that is in between two or more earth or sand and gravel fill that slopes down to the edge of the wall.
Retaining walls are used to support any large structure or surface that wants to be built on a sloped location.
The retaining wall is a structural structure made of rock face materials such as stone, concrete, and even asphalt.
The main purpose is to hold building materials and hold the earth up from below ground.
In fact, in most sloping yards the retaining wall is built by using the materials above ground like concrete.
Many retaining wall examples are seen at the sides of built structures like homes and can be found on hillsides, mountain slopes or riverbanks.
What are the components of a retaining wall?
Retaining walls that support the soil and retain a specific level have the following four components:
- Stem
- Toe
- Heel
- Shear
Four basic types of retaining walls
While the terms retaining wall and retaining structure are often used interchangeably, they’re not just practical, though: they can also add a little style to your yard depending on the type you choose.
There are actually four different types of retaining walls: gravity walls, cantilevered walls, sheet piling walls, and anchored walls.
Gravity walls are the most basic type of retaining wall. A gravity wall is one that relies on its own weight to hold back the soil behind it. If you’ve ever seen pictures of a castle, then you’re familiar with the basic idea behind a gravity wall. Gravity walls can be made of brick, stone, or any other heavy material.
Cantilevered retaining walls are another common type of wall. These walls are supported by a few columns or beams that “hang” over the soil. They’re called cantilevered walls because they can be built from one end to the other.
Sheet piling is a type of retaining wall that’s sometimes used to replace a traditional retaining wall. They utilize panels of sheet, often wood, steel, or vinyl piles. These walls are built with posts, which are spaced at intervals. The post spacing is usually around three feet apart, though it can vary depending on how strong the soil is.
Anchored retaining walls are the most recent addition to the list of types of retaining walls. These walls are built on a footing that’s buried under the soil. They’re built on a slope, and they’re anchored to the slope with steel cables or concrete.
Retaining walls problems
1. Uneven ground level and retaining wall problems
If you are a homeowner interested in landscape architecture you probably have wondered how to create a retaining wall of different heights and a uniform grade.
We have all encountered different levels of retaining walls where the ground level at different locations in the front yard are not the same.
A retaining wall is used for preventing the slope from falling off to the lower side of the yard.
We think of retaining walls as being an important factor when laying out a backyard environment but are often surprised when there is an uneven ground level problem.
Although some of these problems can be eliminated by using the right soil composition or a landscaping technique in the right location, there are a myriad of causes for a bumpy ground.
The ground-level issues may arise when building or clearing the lawn to maintain a flat surface for a patio, drive, pool, etc.
Not all retaining walls are the same – whether you have uneven ground, steep decline, a poor foundation and poor slope/angle, improper installation or poor quality (like the nails in your brick walls) – this all could cause your retaining walls to deteriorate.
2. Land slippage and stone movement
These are just some of the conditions in which homeowners have to deal with at home.
The cause is quite obvious.
Slippage occurs at the edge of the earth.
As you go up, the soil loses its compacted state, and tends to bulge out at the end of the sloping earth’s edge.
This slip may be due to a variety of reasons, chief among them rainfall, earthquake and human activities.
Landslides are quite natural.
But because they take place over a vast area, the land surface and weak rocks or stone pushed downwards by gravity may affect the land shape of gardens for the entire neighborhood if not community.
There may be cracks where one side of the retaining wall meets the other.
3. Hardpan or expansive soil
One of the most common construction mistakes homeowners make is to build a retaining wall on an expansive soil.
Expansive soil is one of the most difficult soils to build on, because it just doesn’t support retaining walls, either structurally or functionally.
At first glance, it’s easy to see how the hardpan or expansive soil issues could cause problems for retaining walls.
After all, hardpan or expansive soil does not allow for a steady buildup of soil, which can lead to problems over time.
However, there are several other factors that are more important, and it comes down to simple things like: soil moisture, correct slope, and proper elevation.
When can you add a retaining wall to an existing one?
The best time to install a retaining wall around your house or building is after the old one shows signs of crumbling, weakness, cracks, or failure due to weather or age.
Where you install the retaining wall can also affect the materials you use and how your design looks.
For example, if your retaining wall is located on a hill or hillside, you may want to use more vertical elements such as stone or concrete, if possible.
If your house is on a slope, it may be a good idea to install a deck or patio around it.
This will provide a place to sit and enjoy the view.
The telltale signs of a deteriorating retaining wall
Retaining walls are everywhere, and there are a variety of ways to add them to a property.
But are you aware of the height of your retaining wall, or are you just counting the number of bricks?
An existing retaining wall may now be at a height that’s too low for the drainage or garden it’s designed to support.
Walls can fail by being substandard, old or simply overwhelmed by soil after erosion, heavy rains or landslides.
When you build a retaining wall for your own garden, you need to let the natural forces of erosion and settlement do their work.
A retaining wall is supposed to protect your garden by preventing soil from washing away, but if you have a poorly built retaining wall that is eroding or leaning, the wall’s potential for producing a garden is limited.
When a retaining wall is built incorrectly, it can lead to a permanent loss of soil from the entire area surrounding the retaining wall, thus ruining the soil for future planting.
This is a problem for home gardeners and professionals alike, and leads to the creation of another wall, or even a second retaining wall, to protect the soil from further erosion.
What to consider when evaluating walls that have already been built
When evaluating a wall that has already been built, there are a few factors to consider.
First, how much weight is the wall expected to hold?
Secondly, is the wall still in good condition?
Thirdly, what type of wall is it and where will it be installed?
Fourthly, is the wall a part of your house that you want to retain?
Fifthly, what is the aesthetic quality of the wall?