When I was young and traveled cross country by road, I saw these iron or net wire mesh going on for long stretches in hill and mountain highways. It covered several tonnes of rock. I was told it was used to retain rock during landslides. Later I came to know that this isn’t some advanced practice concocted by the geological department to protect travelers. In fact, it is extremely ancient, and its uses have been varied across time.
So, let’s start with a brief history of what exactly this mesh is and what does it do and where has it come from.
What’s A Gabion?
It’s called a gabion, the name deriving from the Italian word gabbione which means a big cage, which in itself is derived from an older Italian word gabbia that has its roots in cavea, Latin for cage or enclosure. With its roots lying in Latin you can gauge just how old this technique is. It is so because it isn’t too tough to figure out and once you do install it, it has several applications.
It usually comes in three forms: the most popular one being a box-shaped mesh filled mostly with large sized rocks, but it is also found in cylindrical and cage-like shapes with soil, sand, and concrete used as alternatives for rocks. The elements are used in civil engineering, in building roads, by the military and yes for landscaping, the topic of this blog post.
What Does It Do?
Gabions have been used by the military instead of trenches to protect soldiers from artillery fire. Cylindrical gabions are used for creating a sound foundation in dams. The San Marco, a Milanese castle, had help from the famous Leonardo da Vinci who created a foundation of gabion that’s known as Corbeille Leonard. Cages, on the other hand, help in controlling erosion and flood control.
But, for landscaping, they can be experimented with concerning designs and quantity. After all, gabions look beautiful. There is a strange appeal to orthodoxical and skeletal architectural designs as opposed to the neat and polished styles of the more modern times.
Bored of the traditional pallet or plank fence? Use a gabion wall instead. Don’t want to go through the hassle of a finely constructed set of stairs in the backyard? A gabion staircase is perfectly alright. Want to add more volume to the thin fountain wall? Wrap it up with gabion. It does have its uses. And without further ado, let us delve deep into them.
How indeed. You might be wondering how well the mesh used for the rocks will hold up and for how long. What if it falls apart and you have an entire structure tumbling down. What if your family member, friend or pet is around. These are all valid concerns but concerns that can be met with and resolved with a clever selection of the material and some reinforcement.
The aforementioned wire does come in a few varieties. Stainless steel wire, PVC coated wire and galvanized steel wire are very common types. Of the three a mix of both galvanized and PVC coated steel wire provide the longest life expectancy, of around sixty years. Using galfan, a special material that lasts longer than normal galvanizing is highly recommended. It uses ninety-five percent zinc and five percent aluminum and when the mesh weathers, the aluminum ages the mesh very aesthetically.
How To Use?
The Cage – Part 1
If you’re planning to do it yourself, then you must first decide what are you using it for exactly. If it is for a small, independent wall in the garden, creating cage boxes as blocks to layer upon is easy. An independent wall is open to different designs that might appear like a life sized lego bricks or a target wall in an old SEGA game. If you’re going with a stepped pattern, you can go for something around six feet by twenty inches by twenty-inches base/bottom layer. You can cover it with a smaller layer, of say three feet by twenty inch by twenty inch and so on. Remember, this is only a suggestion to start first. You are free to tweak and add on the dimensions.
You can also go for a more cylindrical shape or create a ringed wall. Using smaller boxes and laying them on top of each other and bridging them means you can create bizarre and unconventional shapes that work as sculptures in addition to serving your main purpose.
Now that you have readied the cage for the rocks, you might be thinking to move ahead with filling it up. But, before we get to that stage, we need to make sure the ground where your gabion will be installed is ready to hold it. Clay soil, for instance, is a clear no. It is susceptible to distortion due to the obviously enormous weight of the gabion, and you risk an accident by slippage. Ensure this by replacing the clay soil with compacted gravel at a depth of 150 millimeters.
But having a concrete base, is not it. The ground needs to be leveled properly. So, dig it up and using a level check if all directions are indeed on the same level.
If you have grass where the wall is going to be installed, then you will need to remove it, lest it starts interfering and intruding your gabion. Using an edging of 4 inches, which is corrugated and powder-coated, helps keep the grass away. Bolster this by spreading and tucking a weed mat behind the edging and using something like a treated pine to keep it straight. Make sure the edging has been fit properly, and if the ground is being hard to this process, you will need to do a little bit more of digging.
Once you have defined the boundaries for your grass, you can move onto the next step.
The Cage – Part 2
You’ve created the mesh with the recommended or preferred dimensions, but now you need to assemble it. This part can be quite exhausting and will require extra attention to detail so that there are no missing chinks in your caged armor for the rocks to spill out. Fastening a steel mesh is not the same as fastening a knot.
Firstly, lay out the sheets of mesh on the ground. Take five sheets. Put the bottom sheet in the center and surround it with four sheets for the sides. Use a gal steel spiral for fastening the cages by winding it through the edges of the sheets of mesh. Don’t worry, the spiral and the mesh fit with each other perfectly and are very easy to wind, so you won’t find it tough to join the panels together. Just coil it through the edges and once you have covered all edges with the spiral, pinch and secure the end of each spiral with a plier.
When you’re done spiral binding and pinching the sheets together, raise the walled sheets vertically, and fasten the outer sides of the walls with each other using the spiral. Add corner bracing to the four sides of the cage so that when you fill it up with rocks, it doesn’t bulge out. Add bracing ties to each corner halfway the height of the cage stops the rocks in the middle from bulging and adding the corner bracing on the bottom and top corners stops the rocks there respectively.
You can buy broken down rock or break down a big piece into small pieces of about five to eight inches in dimension and some four inches in thickness on your own using a demolition hammer. Sandstone is best for the outer facade of the wall, on all sides, as it is prettier and has a few shades for variety, from pink and red, yellow and brown, to white and black. Use the finer and flatter pieces for the front facing. For the inner filling, using bricks and broken concrete blocks is more than enough. Bricks and concrete are also cheaper to buy and reduce your expenses.
When you’re filling the cage, you’ll notice that fitting them can be a little troubling, especially the corners. So, when you’re filling the cage, avoid right-angled pieces. It is easier to fit them in two dimensions. Also, go by the layer.
The small pieces that you have rejected for the main bulk, use them for filling up empty spaces and for wedging the front facing rocks and tessellating them closest.
Once you have filled up the cages, close them with a layer of gabion sheets and fasten them by spiral binding and pinching the spiral.
You can add big pebbles in the small spaces between the rocks for dolling your wall up a little more.
The same technique can be applied to gabion stair cases. And in case you’re making walls, apply the process for each layer and fasten every layer with the layer below it.
You can try out different designs for your gabion installations. From making a sort of gabion archway to cross through to making your own little Stonehenge, the big ideas are plenty. But, more extreme experimentation is possible too. You can create gabion pots, vases, fireplaces, waterfall walls, ponds, baths and entire outdoor rooms, with gabion seating, tables and benches.
Additionally, you can paint both the mesh and the stones whichever way you please, with the stones themselves not restricted to sandstone. Depending on your budget and where you live, the options are plenty. You can arrange different kinds of stones to create elaborate patterns for the front facing of the gabion. Adding moss, creepers and trailing plants to the gabion brings balance to the rough appearance of the gabion and is more natural to look at. Slices of tree trunks is another option if you don’t want to go with stones.
Now that you are equipped instructions, it’s time to get a paper and pencil and start jotting down ideas and designs. Making a wall has never been this fun!
Featured image via bchoarchitects.com