Set in Stone
A WELL-BUILT GABION WALL IS TIMELESS AND CAN WITHSTAND EARTH’S NATURAL FORCES
A well-built gabion wall is timeless and can withstand earth’s natural forces
In the grand scheme of human history, using terraces to level sloped land is a technology comparable to harnessing the power of fire. Much of the earth’s surface is sloped, making it difficult to use. The more populated the earth has become, the more humans have had to make use of the land they’ve got.
Building a retaining wall to reduce a slope is an ancient skill. You’ll need to understand some basic physics, drainage and soilmovement patterns to build a wall that will last a lifetime. You’ll also need to become familiar with the materials and building structures used to create the unique, strong and beautiful gabion walls we’ll discuss in this article.
What’s a Gabion?
Gabions are rock-filled wire baskets. The word “gabion” (root gabbione) is an Italian word meaning “big cage.” In my opinion, they’re faster to build and less laborious than many other wall types. They’re cheaper than concrete landscape-block walls, and they’re cheaper than a dry-stack stone wall, if the stone is purchased at retail price.
Gathering stone yourself is probably the cheapest wall-building method. Railroad-tie walls are cheap, but they’re labor-intensive and only have a 20-year lifespan. However, in building a gabion, you don’t have to lift heavy blocks, rocks or timbers by hand—with the right equipment. If built correctly, a gabion wall will last a lifetime. Most of the hand-labor is in constructing the wire baskets. A tractor with a bucket loader is important for easily putting the rocks into the baskets.
“Keep the segments of the wall small so the baskets maintain a rigid structure to contain the rocks.”
Is a Gabion Wall Right for You?
I chose to build gabion walls around my home based upon three considerations: aesthetics, finances and ease of construction. Gabion walls have a unique and complex visual appeal. The manmade-grid look of the wire contrasts with the natural shapes
of the rock, creating a modern, yet rustic look. A gabion wall at your home will set you apart because they aren’t often used in residential applications. However, I find them very practical and easier to build than many alternatives. The materials are readily available and inexpensive.
I’ve built multiple types of retaining walls using all types of materials, including gabions, natural stone, railroad ties and concrete landscape blocks. In the Ozarks of Arkansas, where I live, retaining walls are very common. I spent eight years in the professional landscaping business, and one of my main duties was building retaining walls. I’ve had the experience of seeing walls I’ve built maintain their integrity for more than a decade. Future decades will continue to tell my story, pass or fail, in Ozark wall building.
“Many road departments use gabion walls along interstates and roadways.”
The Beefier, the Better
I’m amazed by how many walls don’t last. In my opinion, you can’t “overbuild” a retaining wall. The static pressure exerted by soil on walls over long periods of time is amazingly strong and difficult to understand. Soil moves, gravity pulls everything downward, and the weight and the earth’s strength pushing on a wall is significant, even if the wall is only a few feet tall. It’s even more significant if the wall is 3 to 5 feet tall.
If not done correctly, a wall will slope forward within a few years and be face-first on the ground within a few decades. However, gabion walls are unique and completely porous, allowing water to freely flow through, which diminishes the pressure on the wall. Water-logged soil is extremely heavy, and by giving the water an exit path, pressure is released. No drains are needed on gabion walls; the wall is the drain.
For my gabions, I chose 4x4-inch grid livestock panel purchased from the local farm store. These panels are 16 feet long and 4 feet tall, and are readily available across the country. I paid approximately $30 per panel. However, there are many options for types of wire. Whatever you choose, it must be strong enough to support its own weight and that of the rocks. Choose your grid size based upon the size of rocks you’ll be using. If you’ve got big rocks, then you can have bigger grids. Wire
with bigger holes is usually cheaper. You’ll need a pair of bolt cutters to cut the wire.
Secondly, you’ll need some heavy-duty galvanized wire that won’t rust. The wire is very important because it holds the basket together. Don’t skimp on wire; buy more than you think you’ll need. You’ll also need some good pliers, dykes or wire cutters. If you build a large wall, your hands will be worn out from all the cutting. I recommend spending an extra $10 on quality pliers.
The third material needed is the rock. Every region of the country has local gravel and rock supplies readily available. I used oversized river gravel native to the Ozarks, primarily because of its look and color. However, it would have been easier and cheaper to use bigger, chunkier rock.
Most regions of the country have quarries that produce oversized gravel 4 to 6 inches in diameter. Many road departments use gabion walls along interstates and roadways. They typically use the most inexpensive rock type, so take note of the materials they use for your own project.
Constructing the Walls
In my experience, this type of gabion is adequate for walls less than 4 feet tall. I personally wouldn’t build one any taller. There’s no need for a foundation or for burying the base of the wall into the ground. Strength isn’t gained, because the wall isn’t rigid. A critical action, however, is to create level surfaces on which to place the wire baskets. The top of the wall will only be as level as the ground underneath it. Use a string level, transit or even a long level.
Building the baskets is simple. Measure the wall dimensions and use a bolt cutter to create the sides of the baskets. Then, use galvanized wire to join the sides. Put sections of livestock panel every 4 feet or so that run perpendicular to the face of the wall. These strengthen the wall.
Another critical construction aspect is using tee posts as deadmen. In wall building, the term “deadman” refers to a horizontal structure that goes back into the bank, holding the wall and soil bank together. When building a dry-stack wall, you use long rocks that sink
back into the bank. For gabions, I use tee posts. I hammer in the tee posts, and then wire them to the baskets. The tee posts are also held in place by the gravel surrounding them. Place a tee post about every 5 feet. In shorter walls, you can hammer the tee post straight down in the center of the baskets and surround them with gravel. These deadmen are critical to hold the baskets in place when pouring in rocks.
Keep the segments of the wall small so the baskets maintain a rigid structure to contain the rocks. If you have a 16-foot wall, you’ll need to place a divider about every 4 feet. Different types of wire will require different spacing. The idea is that the basket will have enough support to maintain its shape without bulging. I used sections of livestock panel to create the dividers. In between the dividers (every 2 feet), I put a wire jumper to keep the middle sections from bulging. For dimensions, I made my smaller wall 2 feet high by 16 inches wide. My larger wall is about 3 feet high and 20 inches wide. The taller the wall, the wider I like to construct it.
Add the Rocks
Once the baskets are set, level and sturdy, you can begin pouring in the rocks. The deadmen must be secured to the baskets, because they’ll be the only support (don’t backfill with dirt until the wall is complete). If the baskets aren’t anchored, the weight of the rocks will push the baskets. Use a tractor (consider renting one if you don’t own one) with a bucket to pour in the rocks. On my wall, I poured in sections of about 6 to 10 inches deep, then hand-fit the outer rocks so they looked good. Of course, this takes time and is optional. Once the baskets are filled with rocks, you can backfill dirt behind the wall. Done!
(below, left) Use a pair of bolt cutters to cut the wire into the sections you’ll need to create appropriately sized baskets.
(below, right) Use galvanized wire to build topless and bottomless wire baskets. Don’t be afraid to use a lot. The baskets get their strength from the wire.
(opposite) You don’t have to build the baskets in place. You can build them where it’s comfortable, then set them in place when finished. PHOTOS BY CLAY NEWCOMB
(above) Be sure to level the ground beneath the walls. There’s no need for a footing or to place the base of the wall underground. (below) The author uses tee posts as deadmen. These support structures are both in the wall and in the bank. They should be wired securely to the baskets. They also keep the baskets in place when you’re filling them with rocks.
PHOTOS BY CLAY NEWCOMB