All About Earthbag Retaining Walls (Best Material to Use)

A photograph of a tall earthbag retaining wall made from white polypropylene earthbags filled with aggregate material. Above the wall is a bright blue sky, and a heading is written across the top of the image with the words "All About Earthbag Retaining Walls (Best Material to Use)." In the lower center of the image is a badge with "Best Quality" written in red lettering on a white background and red and white stars.

Retaining walls provide a way to make sloped areas functional by providing extra support, preventing the earth behind them from sliding down the slope. They are often used to create level areas, such as terraces, on hillsides and help to prevent erosion.

While most of these walls are built with concrete blocks, poured concrete, or bricks, earthbag retaining walls offer a sustainable option for green building enthusiasts.

While concrete and block-based retaining walls are strong enough to create flat slopes and prevent the downward flow of water and soil in even the most challenging cases, they can have a significant environmental footprint. The cement process and the concrete industry are responsible for up to 8% of global carbon emissions, contributing to climate change.

Earthbag retaining walls offer a more cost-effective and sustainable landscaping option.

This article is all about earthbag retaining walls. I’ll discuss what these walls are, how to make them, and the best materials to use. Keep reading!

Earthbag Retaining Walls: The Background

An earthbag retaining wall made with light brown bags has green grass growing between courses of bags.
Earthbag retaining walls blend better with the environment than concrete or brick walls. They contain less embodied energy and are cheaper to build, too.

Earthbag retaining walls take on the earthbag construction concept, a technique for building walls using sandbags.

Historically, this natural building technique was used in military bunker construction and building flood-control dikes. It’s an easy DIY technique that entails filling earthbags with aggregate and using them to build walls.

Earthbag retaining walls are built with sandbags filled with soil, gravel, and sand from the construction site. They don’t require you to source materials from afar, which cuts down on carbon emissions from transportation and is cheaper.

The Construction Process for Earthbag Retaining Walls

Getting the basic components right is the first step to building a sturdy earthbag retaining wall that will stand the test of time.

The main components of an earthbag retaining wall include the following:

  • Bags: They provide form for clay, dirt, and sand, eliminating the need for bricks. You’ll place the materials into these bags and use them to build the wall. The best materials for the bags are burlap and polypropylene due to their strength, durability, and flexibility.
  • Fill material: This material is for filling the sandbags to create a stable construction base. The most commonly used fill materials are soil, gravel, and dirt. The soil should have a good texture and structure for easy compaction when packed into the bags, and it shouldn’t contain too much organic material, which decomposes, leading to the formation of voids. You can get soil from your construction site or buy it from a local builders’ merchant or garden store.
  • Stakes: Used to hold the bags in place. The stakes should be long enough to penetrate at least 12 inches (30.48 cm) into the ground and firmly support the sandbags during construction.
  • Barbed wire: This is used to tie the bags together to create a stable and secure wall structure.
  • A tamping tool: To compress the fill material into the bags. This prevents the formation of voids, eliminating weak spots in the walls when building the layers.

The Procedure

A photograph of a large earthbag retaining wall that stabilizes a sandy slope in front of a large school building with white walls and black window and door frames. Workers are active on the wall, filling bags with soil.
This earthbag retaining wall stabilizes a sandy soil slope in front of Binayak Bal School, Nepal. Image courtesy of BLOGS FROM ECCA.

Once you have the basic components, you can start building your earthbag retaining wall. Here is the procedure:

  1. Prepare the site and level it properly.
  2. Mark the outline of your wall with a string or stakes.
  3. Place a layer of gravel at the base of the wall to facilitate drainage.
  4. Start filling the sandbags with the fill material. A rule of thumb is to ensure a balance of clay, sand, and dirt.
  5. Stake bags filled with soil, sand, or gravel in place along the outline to create a solid base for your retaining wall.
  6. Use a tamping tool to compact and level the filled base bags. Ensure there are no void spaces in the fill material or gaps between the bags.
  7. Place the barbed wire on top of the base layer before adding a successive layer of filled earthbags to secure them in place.
  8. Continue building up the layers of your wall until it reaches your desired height.
  9. Fill any crevices with gravel for better stability.
  10. Close the seams with mortar or grout if desired.

Reasons Why People Use Earthbag Retaining Walls

Earthbag retaining walls are becoming popular these days for the following reasons.

Sustainability

Traditional building materials like concrete and blocks are linked to the emission of gasses that contribute significantly to climate change.

These unsustainable materials are why the construction industry is responsible for up to 50% of climate change.

Consequently, eco-conscious builders are turning to sustainable building materials like earthbags.

Earthbag construction eliminates the need to source materials from afar, minimizing transportation carbon emissions.

Moreover, building earthbag retaining walls doesn’t require heavy machinery that emits further greenhouse gasses.

A photograph of an earthbag retaining wall made with light brown earthbags. Overlain is a graphic showing green sustainability arrows arranged in a triangular circle.
Earthbags are a more sustainable way to build a retaining wall than conventional concrete or brick approaches.

Cost-Effectiveness

Earthbag retaining walls are cost-effective since they don’t require expensive building materials or special skills like bricklaying. You also don’t need heavy equipment, as with pouring concrete.

The bags are cheaper than bricks, and the construction process is straightforward.

The best part is that building an earthbag retaining wall is DIY-friendly. Consequently, you don’t have to hire a contractor; you’ll save more money by going the DIY route.

In terms of numbers, while building a concrete wall costs between $10 and $60 per square foot (0.09 square meters), earthbag walls can cost as little as $5.07 per square foot.

Flexibility

Unlike concrete, a rigid material, earthbag walls are highly flexible. You can make your earthbag retaining wall into different shapes like domes, arches, curves, and circles.

Moreover, you can build your wall as high and wide as you like. The only limitation is the strength of the bags, so always go for premium quality ones.

Long-Lasting

Earthbag retaining walls are durable and can last for many years. Earthbags don’t require regular maintenance or repainting, unlike other construction materials like wood.

The only downside is that earthbag structures are not waterproof. Therefore, you must incorporate mechanisms to protect them from water damage. Some of the things you can do include:

  • Placing drainage pipes at the base to direct water away from the walls.
  • Installing a sloping roof over the wall.
  • Installing waterproof barriers or sealants on the walls.
  • Stuccoing the walls for better protection.

With proper protection against rain and water, earthbag retaining walls can last hundreds of years.

Erosion Control for Earthbag Retaining Walls

An earthbag retaining wall with water graphics superimposed to show where drainage can take place at the bottom of the wall.
Good drainage at the base of the earthbag retaining wall prevents the build-up of water behind the wall and improves the stability and lifespan of the wall.

Earthbag retaining walls can be highly susceptible to erosion due to soil movement and water pressure.

You can mitigate this problem by implementing geotechnical engineering practices and principles, which include the following.

  • Proper drainage design: Design the foundation to facilitate easy water movement. Besides using gravel for infiltration, incorporate pipes, weep holes, and geotextile membranes to prevent blinding of the drainage pathways. These will help relieve water pressure.
  • Incorporate vegetation: Plant grass, trees, and shrubs at the base of your retaining wall for added erosion control. The roots will anchor the soil in place and mitigate water pressure.
  • Build terraces: Create tiers along the slope leading to the retaining wall to hold and reduce water pressure.

Final Thoughts

Earthbag retaining walls are a cost-effective and sustainable alternative to concrete and brick retaining walls.

Earthbag walls don’t require expensive building materials or special skills to construct and are ideal for DIY projects due to their straightforward nature. So, if you’re on a tight budget, they are an excellent option.

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