What Are the Main Types of Retaining Walls?
There are four main retaining wall types. They are gravity, cantilever, embedded and reinforced soil retaining walls. We can then categorise these four into subtypes based on design, building material and how they accomplish their goal of retaining soil.
No single retaining wall type is necessarily the best. They all have advantages and disadvantages. For example, an ordinary gravity retaining wall is relatively cheap and easy but relatively less durable. An embedded retaining wall is the exact opposite.
So, to choose the best retaining wall type for your garden, you need to consider your preferences, needs and the site’s conditions. Now, we both know that conversation is beyond the scope of this article. So, for now, let’s help you understand the different types of retaining walls.
We will do this by providing descriptions, modes of operation, subtypes and the pros and cons of all four main retaining wall types.
Gravity retaining wall
This is the best option if you need a simple and affordable retaining wall for your garden. In fact, you can even build it yourself by following the guide in this link. The article is helpful even if you don’t have much DIY experience or don’t intend to build a retaining wall by yourself.
A gravity retaining wall type is simple in design. It uses its weight to keep the soil (being retained) in place. This simplicity has both advantages and disadvantages. Construction is easy and relatively cheap. You also get the room to experiment with building materials and designs.
On the downside, a gravity retaining wall is relatively less stable and only ideal for a height of 3 feet and under. However, you can increase stability by including a trench and strong base, and making the retaining wall bottom heavy.
Here are five subtypes of gravity retaining walls.
- Concrete retaining wall: This is a gravity retaining wall built using concrete. The concrete blocks could be stackable or interlocking.
- Masonry retaining wall: this type of gravity retaining wall is built using bricks or stones.
- Gabion basket retaining wall: This gravity retaining wall type is built using gabion baskets. These baskets are tied together to create the wall and then filled with stones. They (the baskets) are usually made from galvanised steel.
- Criblock retaining wall: This type of retaining wall is built with criblocks. Criblocks are construction boxes or frames made using steel, timber, recycled plastic or precast concrete.
- Inclined gravity retaining wall: This retaining wall reclines (slightly with each layer of brick or block) into the retained soil.
Cantilever retaining wall
A cantilever retaining wall is shaped like an L or Inverted T. This is because it includes a slab under the backfill on both or the back side of the retaining wall. Please note that the back side of a retaining wall is the side with the retained soil. The other side is called the front side.
Because of this shape, the retained soil exerts pressure (on the retaining wall) from the side and above. The pressure coming from above helps counterbalance that coming from the sides.
Both the vertical (stem) and the horizontal (base) sections of a cantilever retaining wall are made with reinforced material. Common building materials include reinforced concrete, concrete blocks, and masonry.
All in all, cantilever retaining walls are very stable. However, it’s best to stay within 7 feet, height-wise. Also, the construction of the base can be tasking, especially in a sloped garden.
Apart from the regular type, here are two more subtypes of cantilever retaining walls.
- Counterfort retaining wall: This cantilever retaining wall type has transverse walls on its backside. The extra feature makes them stronger and more stable.
- Buttress retaining wall: This cantilever retaining wall type has transverse walls on its front side. This extra feature improves strength and stability, as with counterfort retaining walls.
Embedded retaining wall
You may also know this as an anchored or sheet-piling retaining wall. As the names suggest, an embedded retaining wall is built by embedding piles or sections into the ground. Then using strings or cables to hold them together.
These piles are usually steel, vinyl, precast concrete or wood. Whatever the material, the piles must be strong enough to bear the weight of the retained soil. However, you can also take additional measures to help them stay strong and long-lasting.
Embedded retaining wall types use passive earth pressure to stay standing and do their job of retaining soil. For the best result, the soil has to be the right type, and you must embed about one-third of the length of the sheet piles. With ideal factors, you can build a tall retaining wall with this method.
Reinforced soil retaining wall
This last type of retaining wall is built by reinforcing the soil itself. There is no need to add foreign materials like wood, stone, concrete, steel etc. However, some people still prefer to add those aforementioned foreign items to act as additional support.
A reinforced soil retaining wall is created using geogrid techniques to increase the tensile strength of the soil, turning it into a stable body. This requires the expertise of a geogrid engineer, but it also allows you to build a taller retaining wall. However, reinforced soil retaining wall types are only possible with specific soil types.
As this article ends, here are three things you need to know. Firstly, most retaining walls can fit in more than one of the four main categories. For example, an embedded retaining wall can also be a cantilever or a gravity retaining wall type.
Secondly, more than one retaining wall type can be used together. This is often used to build a taller and more stable wall.
Finally, it is better to consult professionals before choosing a retaining wall type for your garden. You will probably need both a geotechnical and a structural engineer. The former will conduct the surveys and collect data, while the latter will design and head the retaining wall construction.
While you are waiting to reach out to them or hear their opinions, here are 25 Wonderful Retaining Wall Ideas.