How to Build a Block Retaining Wall

Give your plain landscape a stunning makeover with an attractive block retaining wall. Learn how to build one for your yard in this Lowe’s video:

The blocks for this project have a locking flange which makes the installation easy, and they can be used to build walls up to 28 inches high. For a complete tools and materials list and detailed instructions for this DIY project, click here. Installation is easier with two people; if necessary, use a back brace.

It’s smart to plan your layout. Avoid having downspouts pointed at the wall, and if it’s against the house, keep the soil bed well below the siding. To mark a free form layout, use a rope or hose to outline the shape, then use a shovel to mark the outline. For straight lines, mark the entire bed area with stakes, string and marking paint. Make curved corners by tying the string to a stake that’s equidistant to the edges, creating a compass, and spraying the curves with marking paint.

To determine how many blocks you’ll need per row, divide the total length of the wall by the length of the block. To determine the number of rows you’ll need, divide the ideal wall height by the height of the block. Account for the first row to be half buried. Purchase 10% extra material to account for breakage and repairs.

Before you start digging, call 811 to locate utilities and check local building codes and Homeowners Association regulations.

With the layout marked, you can begin digging the trench. To bury the first row about half way, dig the trench about 4-6 inches deep and 12 inches wide, or twice the width of the block. If the trench slopes, you’ll have to step up or down to keep the blocks level. Tamp the dirt down with a hand tamper and keep it level. Next, fill the trench with about 3 inches of paver base, spread it with a rake, and tamp it down. Wet the paver base if it’s dry and dusty. Tamping the base provides a strong foundation. When it’s all level, you can begin installing the blocks.

For row 1, knock off the flange with a hammer and chisel so the blocks will sit flat (be sure to wear safety gloves and glasses). Beginning at the end with the lowest elevation, set the first block in place and check for level (both side-to-side and front-to-back). Then place the next block, making sure it’s even with the first. Continue installing the first row, periodically checking for level. Fill in under low blocks with paver base, or tap down high blocks with a rubber mallet. After installing each row, sweep dirt off the tops.

To start the second row, you’ll have to cut a block to stagger the joints. Mark it, then cut it with a masonry blade (use safety gear). Put it in place, keeping the flange tight against the first row, then check it for level.

When installing the next few rows, you’ll need to add drainage directly behind the blocks. Lay down landscape fabric behind the wall, leaving enough excess to reach the top, then fill in directly behind the wall with gravel as you continue to build.

For the last two rows of full blocks, apply concrete adhesive to the wall, then set the blocks in place. Now, just fold the excess fabric back and fill in with soil and plants.