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How to Build a Small Retaining Wall (8 simple steps)

How to Build a Small Retaining Wall (8 simple steps)

Retaining walls are undoubtedly one of my favorite landscaping fixtures. They strike the perfect balance of utility and aesthetic — serving a real purpose but looking really good while they do it. You can make them out of all sorts of materials, including brick, cinder blocks, rocks, logs, railroad ties (yeah, seriously), and more.

If you’re in need of a modest retaining wall, you don’t necessarily have to reach for the phone to dial a professional. In fact, building your own small retaining wall is entirely doable. Don’t believe me? Here are the simple 8 steps to build your own.

Here’s how you can build a small retaining wall:

  1. Decide and design the location of your retaining wall.
  2. Dig a trench wide enough for the base stones to fit into.
  3. Lay landscape fabric into the bottom of the trench.
  4. Lay down base stones tightly, covering the fabric.
  5. Start the second layer of stones in a staggered pattern. 
  6. Ensure your retaining wall is level. 
  7. Fold the excess landscape fabric over the top of the wall.
  8. Install the capstones tightly.

I know — 8 steps seem short on paper but much longer when you have drips of sweat running down your face. If you don’t know where to start, read on! This article will cover what kind of materials you’ll need, how to design your retaining wall’s location and go into detail for each step so you’re not left high and dry..

1. Decide and Design the Location of Your Retaining Wall

The first thing you need to do is decide where to place the wall on your property. Wherever it is, make sure that there’s enough room for the wall and that nothing will be in the way once you start building. 

Designing a retaining wall requires a lot of patience and knowledge. You have to take into consideration many factors, such as: 

  • The angle of the slope
  • The position in your hard
  • Height
  • Soil conditions 

Make use of string or marking paint to design where your wall is going to go. When picking a location for your retaining wall, avoid areas that may flood during heavy rains or storms.

Also, consider whether or not anything will be growing near or behind the site after construction. You’ll want to ensure that you don’t build your retaining wall near trees or plants with large, invasive root systems. 

2. Dig a Trench Wide Enough for the Base Stones To Fit Into

Begin by digging a trench for your retaining wall. The depth of the trench will depend on the desired height of your wall and the type of material you use.

Dig a trench wide enough for your base stones, especially if you’re building a natural stone retaining wall. The base stones will act as both support and drainage for your retaining wall. Ensure the bottom of the trench is level, and use a hand trowel to make sure it’s smooth. 

A standard method for constructing a low-cost retaining wall involves using railroad ties as an easy way to make the necessary frame for the structure. Not only are they cheaper, but these materials are also very sturdy. You can also use them for this application without any problems.

If you plan on building a more permanent type of retaining wall, consider using stones or bricks as your base material. You can even purchase stone blocks, though it depends on their costs and availability in your area. However, they may be rather expensive and time-consuming to transport and place around the wall’s foundation.

Regardless of what materials you use for your retaining wall, you must place them below ground level at least 3 inches (7.62 cm) before filling them with soil or rocks. This allows for proper drainage and added strength for such an elevated surface.

3. Lay Landscape Fabric Into the Bottom of the Trench

Lay down landscape fabric in the base of the trench. It’ll help prevent weeds from growing up between the stones in your retaining wall. A landscape fabric with a weed barrier will also help prevent roots from growing through your stones and into your garden below.

The most common landscape fabric is a polypropylene woven fabric with a diamond pattern that allows the water to drain without weeds or grass growing up through your stones.

These materials are all readily available at any home improvement store, and most come in several different sizes. You can be sure to find one that’s just right for your project’s needs. You may have to order some larger items from a specialty supplier, though.

4. Lay Down Base Stones Tightly, Covering the Fabric

Lay down the base stones of your retaining wall on top of the landscape fabric. There should be enough fabric to cover the back of the retaining wall, reaching all the way up to the wall’s capstones. If you have a curved wall, use the excess fabric to fill any gaps between the stones.

Lay the base stones of your retaining wall tightly together. You can overlap them like shingles or lay them side by side.

Apply a mortar compound to both sides of each brick or stone with a trowel before placement. Fill in any cracks between bricks or stones. Make sure that the mortar is applied thick enough so that none will be detectable between each course but thin enough so not too much oozes out while placing them one on top of another.

Mortar can take 24 hours or more to fully set and harden. Use the handle of your trowel to smooth out the mortar compound, or use a damp sponge to wipe off excess material. This will give your wall its finished appearance and help it last longer.

5. Start the Second Layer of Stones in a Staggered Pattern

After the base stones are laid, begin laying the second layer stones. Use a staggered pattern, laying one stone over the gaps from the first layer.

The height of your retaining wall will depend highly on your personal preferences and the landscape surrounding it, but make them as level as possible to prevent future settling along your wall. Be sure to secure each stone with mortar to ensure the wall’s stability.

Another possibility is to build your retaining wall with interlocking blocks, which you can stack like regular bricks to avoid using mortar. Most of these should also be covered in mesh to aid in securing the individual stones.

The top layers should be laid tightly together, without spaces between stones. Make sure they’re as level as possible to avoid creating a trip hazard or damaging any plants that may try to grow along their length in the future. 

You can cover up cracks and other spaces that you may not have filled with rocks using sand or soil. Filling in those tiny spaces will create a more solid, level wall. In some cases, you can stack smaller rocks around the larger ones to fill in these spaces.

6. Ensure Your Retaining Wall Is Level

Set a level on top of the wall to ensure your retaining wall is level. Move down along the wall, checking each section to see where your line is off. If it’s not level, you can move some rocks around or add in layers of sand and soil until it reaches what appears to be an even height all around. You may need to start over with a couple of new rocks to get the height correct.

Make sure your retaining wall is sturdy. To test if it’s steady and strong enough, push on it lightly at first. If you don’t feel any give or movement, apply more pressure. If something budges slightly, it indicates that your wall isn’t stable enough and may need reinforcement materials to strengthen it. 

If you feel anything give even slightly, try adding layers of sand or soil until there are no more weak points.

7. Fold the Excess Landscape Fabric Over the Top of the Wall

Once your retaining wall is level and sturdy, fold the landscape fabric to cover the back of the wall and secure it with adhesive. The capstones will be placed on top of this layer to further hold down the fabric. 

Add gravel or sand into the space behind the wall when the fabric is secure. This will help prevent erosion and aid with drainage. Fill the rest of the open trench with soil. 

8. Install the Capstones Tightly

Install the capstones tightly with the same compound used to build the rest of the wall. The capstones will further secure the landscape fabric and prevent erosion or movement due to weather.

If you live in an area that experiences lots of rain, you’ll want to add a drain behind your retaining wall. One way to do this is by installing a drainage pipe with a hole drilled into it at the lowest point on the back of the wall. You can then pour more gravel into that trench or another dry well to divert water away from your foundation.

You can also consider reading our article about how to finish the ends of your retaining walls, for a more in-depth look at this step.

Conclusion

Building a small retaining wall can help to add curb appeal, provide support for plant growth, and prevent soil erosion.

Most DIY enthusiasts can complete such a project, but if you live in an area that experiences lots of rain, you’ll need to know how to add a drainage system behind your wall or divert water away from your foundation with another dry well.

If you’d like to know more, we have a complete retaining wall resource. If your job is a bit larger, but you’d still like some cheap ways to build retaining walls, we wrote about that fully at this link.

Sources

The Major Differences Between Retaining Walls and Regular Walls – Captain Patio

Friday 15th of April 2022

[…] build a retaining wall, the first step is to dig a trench. This can be done by using either a shovel or post hole digger, […]

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