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04/22/2022

Landscaping 101: How to Build a Stone Retaining Wall in 10 Steps

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If your property features sloping ground or different levels of landscape, you might find building a stone retaining wall to be just the thing. Stone retaining walls allow you to expand the usable space in your yard, create a beautiful, terraced look at your home, and control erosion, as many homeowners of Columbus and Cincinnati have found.

If you’re wondering how to build rock retaining walls with outcropping stones, follow our step-by-step guide. DIY stone retaining walls are not too technical or too difficult if you prepare well, take your time, and make each of these steps.

Prepare All the Equipment Necessary

The first task is to get your materials together. Rocks, of course, are number one on the list, but you’ll also need an array of other items to get the job done. These include:

  • Landscape fabric
  • Gravel
  • Sand
  • Screenings
  • Wood stakes
  • Shovel
  • Wheelbarrow
  • Line level and string
  • Four-foot level
  • Rake
  • Mason’s line
  • Mallet
  • Maul or sledgehammer
  • Tamper

Plan Your Build

Before you start building rock retaining walls, you want to make sure you have a solid plan in place. Your first consideration, of course, is the size and scope of the project.

How tall is your wall going to be and how long?

These are critical pieces of information because some communities have regulations for retaining walls over 30 or 36 inches.

The height of your wall will dictate how wide it needs to be. The rough rule of thumb is that you want a foot of thickness for every vertical foot. If your wall is five feet tall, the base should extend five feet back.

Once you have the basic size, consider the type of stones your job requires. How much pressure will be exerted on the wall? How steep is the slope you’re holding back? Answering these questions will get you ready to begin your build.

Organize the Stones and Mark the Level

building a stone retaining wall
Retaining walls

Next, start to get a sense of your building materials – in other words, get to know your rocks. Make piles on the ground nearby, separating stones by their size and weight and by how square or attractive each one is. Stone Center sells gray outcropping stone that works perfectly for installing a stone retaining wall.

When you’re ready to begin construction, use the widest and heaviest at the base and work your way up to the best-looking stones, which will be on top. Unusual shapes can be mixed into the middle. Remember, too, that you can use a hammer and chisel to cut and trim and make rocks fit where you want them to. You can also use these tools to create shims that will keep your wall rugged and level.

Once you have yourself organized, grab your mason line and wooden stakes and layout where you want the wall to go. Hammer in the stakes and tie string around them. Remember to accommodate the required width-per-height ratio.

After the string is taut, mark the front edge of your base, and use a line level to make sure you have a straight, level line. This will give you the dimensions of the base of your wall.

Excavate the Area

Now comes the hard part – the big dig. You’ll want to carve out a trench about a foot deep and as wide as your base. The 12 inches below grade will give you enough room to fill in with drainage rock and the first big blocks that will anchor your base.

Lay Down the Base

At the lowest level of your wall, you’ll want to pour your gravel about five inches deep. Once it’s down and raked evenly, use a tamper to compact the stone. Over that goes an inch of sand, which will fill in cracks and provide a smooth bed for the first building blocks.

Lay Down the First Level

The biggest and most durable stones go down first. Run these in an even line so that they just touch the front of the string. You want them to lay as flat as possible, creating a level surface on top. To do that, it may be necessary to dig out or add sand.

Lay Down the Second Level

The next layer is slightly trickier. You again want to use large stones, and it’s best to offset them so that they cover the spaces between the rocks below.

Place each of these stones about a thumb width further back from the string then the first course. That will help provide structural stability to cope with the pressure that backfill will apply.

Just as before, make sure you’re using your four-foot level to keep the surface even at the top. In some cases, it may help to use smaller rocks as shims between the first two levels, to make sure everything is solid and well interlaced.

Backfill the Wall

Once you have built your wall up to two levels, it’s time to fill in behind it, with drainage gravel. Use the same technique you used in the trench at the base – pour, rake, smooth, level, and tamp it down. At this point, you only want to go as high as the second level of rocks.

Lay Down More Levels

building rock retaining wall
Retaining walls' levels

Each of the subsequent courses goes down as the second course did. Move the stones back a half-inch from the string and overlap the seams beneath. Try to keep them tight together and level on top. This creates a sturdy wall able to withstand the pressure that backfill will exert on it.

On the third layer, you’ll want to add a deadman, which is a long rock that stretches back into the slope behind. These effectively anchor the stones into the fill behind, creating a very solid wall. As you go up, continue to add gravel as backfill.

Finish the Top Level of the Wall

When you approach the final courses, ready your landscape cloth. This goes over the gravel and under the top two courses and will allow you to grow grass behind the wall if you wish. Pour loam down over top and seed it if you want green here. The uppermost stones are the most important as they’ll have the biggest aesthetic impact.

You want to make sure you save the best stones for last. Some people will shape these top stones using a hammer and chisel so they look just right. Others might use cement to ensure they stay in place.

Conclusion

Retaining walls are lot of work, but they can be a great complement to your yard. Well, they become an attractive feature that allows you to expand your yard into previously unusable space. If you follow these steps, you’ll end up with a sturdy wall that will stay in place for decades.

If you need any advice on how to build a DIY stone wall retaining, want to buy natural stone, or are looking for other support with landscaping projects, contact us at Stone Center. We have stores in both Columbus and Cincinnati and offer a full range of hardscaping services to the residents of Ohio.