Building Retaining Wall Corners
Retaining block walls are a common landscape feature found in garden beds, flower beds, and other areas on the lawn. They are typically made from concrete blocks. Building retaining wall corners can be a tricky DIY home improvement project. However, you can definitely tackle this project with the right tools, preparation, and by following step-by-step instructions.
Homeowners should carefully consider the type of block to buy for your retaining wall design. This is because the type of block used determines how you can build your corners and curves. Some types of blocks come with corner units that make the job simple, and others are finished on all sides, leaving the corners exposed. When choosing blocks, make sure you have the tools and instructions for whatever corners, curves, or special circumstances you have in mind.
Here are some tips for tackling corners in your DIY retaining wall project.
One-Sided Blocks
The most common blocks for retaining walls are textured only on one side, with a lip at the back that presses against the row under it. They’re often wedge-shaped to allow for turns and curves. This type of block is designed more for curves than sharp corners, since only one side of the block is meant to show.
To construct retaining wall corners using wedge-shaped blocks:
- Outside Corners: Most retaining wall outside corners built with wedge-shaped blocks are curved, rather than at a 90° angle. This is because it’s impossible to make an outside corner without showing the cut, smooth end of the blocks. Wedge-shaped blocks are easily laid in a curve, or you can cut the sides of rectangular blocks to achieve the same curved effect.
- Inside Corners: It’s easier to build 90° angle inside corners with wedge-shaped blocks, since the backs and sides of the blocks won’t show. Start the first course of blocks in the corner, then overlap the joints in each additional row of blocks, cutting any odd-sized blocks to fit.
Corner Units
If you’re using stackable blocks that are only textured on one side, the best solution is to choose a block system that comes with corner units. The cornerstones are finished on two sides and connect to the adjoining blocks to form a 90-degree angle.
Each system is designed differently, so each type of corner unit will have slightly different installation instructions. In general, you’ll start at the corner and work your way out. The corner block from the second course of blocks should alternate in direction from the base course, and should continue to alternate for the next course, and so on. With this method, you may need to cut stones to fit the desired length of your wall. For this, you will need a chisel.
Multisided Blocks
If your retaining wall blocks are rectangular and finished on at least two sides (like many pavers and cinder blocks), you can easily stack them to create a corner. Alternate the pattern to divide the load and keep the corner from splitting, and be sure to use some masonry adhesive to hold the corner pieces in place until you reach your desired wall height.
Retaining Wall Corners: All About the Material
Building a DIY retaining wall can be hard, but with the right tools and instructions, the average homeowner can do the project. I’ve given you an overview of how different blocks support different goals. Choose a material that supports your design idea, and follow the step-by-step instructions that accompany the product for the best success.
Further Information
- How to Build a Stackable Block Retaining Wall (article)
- How to Align Blocks in a Curved Retaining Wall (article)
- How to Cut and Install Retaining Wall Topper Stones (article)
- How to Build a Retaining Wall with an Outside 90° Wall (wonderhowto.com)
FAQs About Building Retaining Wall Corners
What Tools Do I Need to Install a Retaining Wall?
To install a retaining wall, you’ll need a few tools. You’ll want to have a shovel and spade, level, tape measure, a hammer, or mallet, a chisel, and safety gear. Helpful tools include a wheelbarrow to move the heavy blocks and supplies, string line, and stakes, and a gravel rake.
How to cut retaining wall block for corners?
Cutting retaining wall blocks for corners is an important skill for creating a clean, professional-looking finish. You’ll want to start by measuring and marking the cut line on the block with a pencil or chalk. For outside corners, you’ll typically cut the block at a 45-degree angle. For inside corners, you may need to cut two blocks to fit together.
For concrete blocks, use a circular saw with a diamond blade or a masonry saw. For softer materials like landscape blocks, a chisel and hammer method will likely work. You should always wear safety goggles, a dusk mask, and hearing protection when cutting materials.
Place the block on a stable surface, and if using a power saw, set the depth to slightly more than the thickness of the block. If using a power saw, guide the saw along the marked line. If using a chisel, score along the cut line deeply, then use controlled strikes to split the block.
You can use a masonry chisel to clean up any rough edges left behind, and then test the piece to make sure it fits.
What are retaining walls used for?
Retaining walls serve several important purposes in landscaping and construction. They hold back soil on sloped terrains to prevent erosion and landslides, increase usable land for gardening or other structures, and manage water runoff to prevent flooding. They can also provide structural support, property line definition, and value increase, and are even used for aesthetic reasons.