Homemade Concrete Retaining Wall

Layout

• Using stakes and string to mark a rectangular layout gives you a guide as you apply the blocks. Place the stakes at the corners of the proposed wall and tie string between the stakes. Spray the ground below the strings with marking paint. When you remove the string and stakes, you simply follow the paint as you dig out the foundation. For a curved design, placing a garden hose along the desired course and topping it with sand allows you to follow the indentations as you dig.

Foundation

• A raised bed retaining wall needs a foundation trench dug about 6 to 12 inches deep and about 4 inches wider than the blocks' perimeter. You should even out the base of the trench with a tamper and check it for level. A 3- to 6-inch layer of gravel should be placed in the trench to increase the stability of the wall. The gravel also needs checking for evenness with a spirit level.

Blocks

• With a rectangular bed, you place the first block on a corner. For a circular wall, you can start at any point. Checking the first block for level helps you maintain a straight row. Depending on the dimensions of the wall, you may need to cut a block to size with a masonry saw to finish the row. Cutting a block in half to start the second row allows you to stagger the courses so the joints do not align; this is important to make the wall more stable. Applying construction adhesive to the underlying blocks before you apply the last row increases the wall's structural integrity.

Finish

• The bed behind the wall needs backfilling with gravel after every two rows. The last 12 inches of the bed should be reserved for topsoil. For walls over 2 feet tall, drainage pipe helps prevent water buildup behind the blocks. To provide drainage, place a perforated drainpipe on the gravel bed, ensuring that it slopes at least 1 inch every 8 feet and empties away from the wall. A piece of landscape fabric should go in between the top of the gravel and the layer of topsoil.