One of the best all-around hardscape elements perfect for just about any landscape is the gabion wall. A gabion wall consists of individual gabions, which are metal wire or mesh cages filled with rocks then arranged in a specific way to create the desired structure. When executed correctly, they not only serve a practical purpose but also enhance the landscape’s beauty. They are a low-cost, low maintenance, and environmentally-friendly way to add a high-end, modern look to your garden. And thanks to their versatility, they complement or blend interestingly into every landscaping style.
Gabions can combine to form other structures besides walls, though that is arguably the most popular use. They also lend themselves well to benches, planters, borders, fences, water barriers, and sound barriers. And, they are right at home in countless decorative applications where they don’t necessarily have a function to perform other than looking good.
Wherever did we get the idea for such a unique concept?
Modern and urban detailing ( like using concrete blocks and a mix of unfinished ceramic dishes in the gabion) make this wall/planter a literal work of art. “Terrace at The New Art Gallery, Walsall” by scrappy annie is licensed under CC BY-NC 2.0
Origins of the Gabion Concept
The Diana Fortress is a military fortification built by Emporer Trajan during the Roman Empire. Built in 100-101 AD, the site made heavy use of gabion walls, portions of which remain intact almost 2000 years later. It is located in Kladovo, in eastern Serbia.
“Diana Fortress (Karataš), remains of the walls” by Institute for the Protection of Cultural Monuments of Serbia / CC BY-SA 3.0
The earliest-known implementation of the concept dates back to the Pharaohs, about 7,000 years ago. Egyptians used woven reed baskets filled with stones to maintain the banks of the Nile. In medieval times, over 400 years later, they were widely used in military fortifications.
In 1879 an Italian firm developed the wire mesh basket design that we still use today. The firm was ‘Ditta Maccaferri Raffaele, Officina da Fabbro,’ established by Raffaele Maccaferri. Today, the company remains 100% family-owned, and they still make the Maccaferri Gabion. It is now used in civil engineering projects, military applications, road building, landscaping, foundations, erosion control, architecture, and coastal environments.
What Type of Wall is a Gabion Wall?
Retaining wall is a broad term that refers to any structure designed to hold earth/soil in place that would otherwise be unable to retain its current shape. There are several different types of retaining walls, and sub-types as well. Though there is not one standardized and industry-accepted breakdown, most professionals would agree that the main types of retaining walls are gravity, cantilever, anchor, and sheet pile.These categories break out further, with gabion falling under the category of gravity wall.
This river rock gabion wall serves as both a property fence and privacy barrier, and happens to make a lovely backdrop for softer elements like the flower bed.
“gabions 02” by Scott Zona is licensed under CC BY-NC 2.0
There are many characteristics that differentiate these four types from each other, but there is one major distinguishing factor: gravity walls generally do not have concrete foundations or footers, whereas the other three do. Instead, they rely solely on their weight – the force of gravity acting on their mass – to hold the retained material in place. All retaining walls, like everything else on earth, are affected by gravity. However, the effect on gabion walls is greater because their mass is greater.
Gabion Walls and Concrete Foundations
The first stop on The Battery’s Battery Point Sculpture Trail, located on Manhattan, New York, is this caged rock piece. The artists? Chained convicts who chiselled into cliff faces to build sandstone warehouses and the new wharf of 1833. “Battery Point 1833” by BaboMike is licensed under CC BY-NC 2.0
Concrete foundations are needed because, behind the retaining wall, the earth being retained is exerting a lateral pressure back against the wall. Retaining walls are relatively low in mass so without the reinforcement, the walls would fail under the lateral pressure. The way gabion walls are designed and constructed makes them so heavy, and gives them such a large mass, they are able to easily withstand lateral pressure without reinforcements.
All that said, there are rare instances when gabions may need some additional reinforcing.
Gabion Wall Pros
Before we get to the building, let’s first weigh the pros and cons to make sure they are the best option for your project. We’ll start with the pros.
The quintessential gabion look. It may appear harsh and austere but they are surprisingly versatile and blend seamlessly into any style of garden.
These structures have a very distinctive look that is minimalist, deconstructed, high-end, and modern. You can instantly add calm to an environment with conflicting design elements or modernize an outdated look, thanks to the ultra-trendy deconstruction vibe they have.
It is far more versatile than one might think. It is often overlooked in this application but makes for a beautifully dichotomous addition to a romantic cottage or victorian garden; a touch of austerity amidst densely blooming flowers contrasts in a way still pretty, just more interesting.
Gabion inserts make lovely backdrops for flower baskets. Though seemingly hard in appearance at first glance, it takes very little plant material to soften the overall look.
If you have a moon garden, consider a small wall, seating area, or planter using an all-white rock as the backfill material. Another beautiful nighttime design: fill the gabions with glass, and run lights inside behind the glass.
Gabion walls are highly customizable. Shown here are just four examples of the different rocks used in gabion walls. Starting top left going clockwise: rip-rap, sandstone, river rock, and DG.
Almost every aspect of these structures is customizable. You can choose the layout, height (to a degree), width, arrangement, and backfill material and create a beautiful piece of artwork designed specifically to your aesthetic. Add-ons like benches, hanging baskets, and planters are easy to incorporate. There are thousands of ways the components can be combined to create thousands of different looks.
Cages can be filled with recycled materials, as opposed to decorative rock, for a more environmentally-friendly option. Broken up pieces of concrete, cement, or brick leftover from a construction job make great fillers.
Evidence shows a gabion wall reduces CO2 emissions by as high as 80% (compared to concrete designs of the same height). That is due to the lack of concrete in the project, which means no cement. Additionally, they can hold not only stone that is minimally processed but also recycled materials leftover from other construction projects, which reduces landfill and fuel consumption.
Gabion walls may become stronger when debris, sand, and other organic matter are allowed to collect within the spaces between the rocks, but what’s shown in the picture is overgrown. The weeds and greenery outside the mesh should be cut away for a cleaner appearance.
There are many characteristics that contribute to the overall longevity of the structure. First, they are durable. They are strong, heavy, and virtually immovable. If silt and vegetation are allowed to collect within the baskets, the structure only gets stronger over time.
Second, they are flexible, thanks to the fact that they do not affix to the ground. Gabion walls usually sit atop the surface, while other elements similar in form and function (like a standard retaining) require a concrete foundation. The structures do not break; instead, they respond to ground movement by making small movements of their own. Individual baskets compress or deform very slightly, as needed, preserving the structural integrity and contributing to their longevity.
Gabions are not affixed to the ground; rather, the individual cages are instead affixed to each other. This modular style of construction allows them to be incredibly sturdy yet flexible at the same time.
Third, their longevity is by design. The materials used during construction withstand exposure to the elements and allow dirt, sand, and debris to enter and collect in the small spaces in-between the rocks. The gabion wall collects this debris for about 50 years before the wire cages break down. When they do, the structure remains intact. Not only that, it is sturdier, more solidified, and cohesive.
Typically, gabion walls do not require a concrete foundation, or use any concrete at all. Therefore, they are cheaper to construct in both labor and materials than walls of the same height made with concrete and cement. And, regardless of the concrete foundation, the overall work involved is less intensive than building a concrete version. That’s valuable time in the bank that you can use toward other endeavors.
If the ground on which they are being installed is hard enough, these structures do not require any additional foundational prep work.
Backfilling the baskets with recycled materials (as opposed to decorative rock) also makes them cost-effective. Purchased locally, they come at a much lower cost. You might even find them for free from time to time if you know where to look.
Additional Upsides to Consider
In addition to the above, gabion walls help repair erosion problems, require little to no maintenance after completion, are constructed quickly, and are highly permeable, eliminating the need for a drainage system.
Gabion Wall Cons
There aren’t many cons when considering gabion walls, and they may not even be cons for you.
These structures have been known to share their space with naturally-growing organic matter such as moss, weeds, and grass. This is purely subjective and may be a con for some, but is a pro for many others.
As pre-constructed cages tend to start at 12″x12″ dimensions, even a small structure might be considered “bulky,” especially in a small space. They are indeed bulky, but they are that way for a specific reason. That bulk usually means that no reinforcements of any kind are ever needed.
Con: Unwanted Animals and Organic Growth
This structure tends to lend itself to providing a desirable shelter to small animals. They can crawl in and make cozy homes among the various nooks and crannies. For some people, this can be off-putting.
From a design perspective, some say gabion structures are too bulky, and that is indeed true. However, that is why concrete foundations are usually not needed. Shown: a gabion structure seating bench.
“Looking at Weld Mesh Gabion Bench Seats” by Bernie Goldbach is licensed under CC BY-NC-ND 2.0
It’s also possible to have algae or moss-type organic matter growing and spreading over the rocks. Many people like this look and some do not; it is strictly down to personal preference.
How to Build a Gabion Wall
By this time, you should have considered all the pros and cons and hopefully determined that this type of structure is suitable for your needs. As gabion walls rarely require a foundation, these guidelines pertain to a freestanding wall.
You should find that it’s a relatively straightforward and uninvolved process. Coming up with the design and deciding which backfill material to use will likely take longer than actually building it.
Here are the steps to follow to build your gabion wall.
Determine the Location
An ideal location for a gabion wall, that will require little to no site prep, is one that is already hard and flat. This allows for the fastest installation. The site shown above requires no concrete, no road base, and no digging of any kind.
If there is retaining to be done, the location will be dictated by the need. Otherwise, an ideal location is one that has a base that is both flat and hard. Pavement, bedrock, and concrete surfaces do not require any digging, which means you can start building the wall from the ground as-is.
One of the many decorative rock options to consider is colored glass. Lights can be put into the cages with the glass and turned on after dark to create a stunning piece of art.
Walls in these types of locations tend to be more decorative, as opposed to functional; that is a trend we have seen exponentially increase in popularity over the last decade or so. If you are in need of a functional retaining wall, keep these important tips in mind:
- You may or may not need a “foundation” of road base or ABC mix, depending on the build-to height and the hardness of the ground. Gabion walls really do their best work, functionally, in the 3’-4’ tall range.
- Depending on the height of the earth to be retained, terracing may be an effective method, which can be done with gabions.
- You may also want to consider battering, which is slanting the gabions back so they are set in the angle of the slope (batter is an architectural term that is the opposite of an overhang).
- When in doubt, be on the safe side and check with an engineer, especially if the retaining wall will be over 4’ tall.
Mark Out the Wall
With the location determined, prepare a ground outline using marker paint, or stakes and string. These are the lines to follow when you begin digging.
Expose Subsoil or Add Road Base
Though a concrete foundation is usually not needed, often a crushed rock one is. If the ground is very soft, you will want to install a few inches of road base or ABC mix.
Remove any organic matter in the way. Grass, weeds, and the upper-most soft layer of topsoil need to be cleared away. Dig down only far enough to hit the hard subsoil layer. This will be your installation surface.
If you do not have a hard subsoil layer (your soil is too sandy or is clay) you will need to dig out the earth a bit deeper to 4″ – 6″. When that is done, backfill the area with a crushed rock mix. ABC or road base works well for this. Last, compact the crushed rock into place.
Assemble and Place the Cages
This is a quick but helpful video of a 3D rendering of a gabion wall project. It includes how to assemble the cages and how to place them.
Cages are usually sold or shipped flat. Most if not all varieties come with instruction manuals for assembly. Once your cages are built, place them in the prepped area. Once they are full, they cannot be moved, so ensure you are placing the empty cages exactly where you want them to remain.
If you are using multiple baskets to create one long structure, link them together after forming so they become one piece.
If your structure is going to be extra thin, you will need to install aerial reinforcements such as steel rods.
Optional: Power Wash and Sort Stones
If your design includes more than one type or color of stone, pre-sorting them beforehand helps speed the process along.
Depending on the material chosen to fill the baskets, it may benefit from a power washing. This will remove the outer dusting of dirt and result in a polished yet natural look upon completion.
If you are working with varying sizes of rocks, now is a good time to sort them.
Fill the Gabions
Each stone inside a gabion needs to be carefully hand-set, though some not as carefully as others. Focus your most detail-oriented attention on and be most conscientious with the outermost layers of rock. This is what will be seen from the outside of the wall, so this needs to look sharp.
How the stones are placed is just as important as the stones themselves. The glass and stone is already an eye-catching combination and an interesting layout adds extra flair.
The rocks behind the outer layers can be placed much faster and with less thought – they will not be seen. They do still need to hold the outer layers up and in place, so ensure they are placed in such a way that it’s a tight fit and sliding or falling will not occur.
As you build up this outer layer, follow behind with the remaining rocks so that the outer layer is supported.
Close and Latch the Lid
Upon completion of the top and final layer of rock, with the basket full, cover the opening with the lid and secure it in place with ties provided by the manufacturer. Metal spiral coils are available for extra-strong connections.
Gabion kits do not usually come with the spiral-shaped helicoils but they can be purchased separately. They are a good idea to use as they strengthen the connections between the cages. “coils in the Gabions” by ianxharris is licensed under CC BY-NC-ND 2.0
Repeat for Additional Courses
Repeat this process for at least one more course, if needed, to reach your desired height (course = row).
Assemble the cage and place the cage on top of the previously installed course. Add your rock material, then secure with the lid.
The Completed Gabion Wall: What Now?
This gabion wall is a perfect example of its versatility and adaptability. It looks great combined with two other types of hardscape, and is the perfect background for these potted plants.
Surprisingly easy, isn’t it? Hopefully, a completed structure isn’t the end of your gabion adventures. Part of their fun is that finished walls can easily be modified and redesigned to incorporate new features. Try building in a seating area or experimenting with the arrangement of the rocks. Or add a complimentary piece, totally original, to make a nice set. A custom-shaped gabion planter like the one below would probably look great with your new wall.
“Gabion Art” by Earthworm is licensed under CC BY-NC-SA 2.0