How to Install Retaining Wall Blocks

A retaining wall is typically installed to help prevent soil erosion in a sloped area, but a carefully designed retaining wall can add to the aesthetics of a yard or commercial property. Retaining walls can be made of poured concrete or railroad ties, but many homeowners opt for a more substantial and longer-lasting design that can be achieved by installing retaining wall blocks. Retaining wall blocks are made by many different manufacturers in various sizes and colors. The blocks can be carved from real stone or poured from concrete into a mold specially created to mimic the look of natural stone.

Things You'll Need

3-inch chisel
3-lb. mallet
Gravel
Construction adhesive or mortar
Trowel

Metal rake
Hand-held sweeper
Level
Dirt tamper
Shovel

Instructions

- 1
  
  A small trench to provides level ground for the blocks.
  
  Prepare the base to lay the first row of retaining wall blocks. Use a shovel to dig a trench at least 6 inches deep. Match the width of the trench to the width of the retaining wall you plan to build. Remove any weeds, tree stumps or large rocks from the trench. Clear way loose dirt and even out the earth with a dirt tamper.
- 2
  
  Finely crushed gravel offers the most stability.
  
  Fill the trench with at least 3 inches of gravel fill. Make sure to use fine crushed gravel no more than an inch in size. Spread the gravel evenly throughout the trench with a large metal rake. Tamp the gravel down to make it as level as possible.
- 3
  
  You can chisel the edges of square blocks to add character.
  
  Use a 3-lb. mallet and a 3- to 4-inch chisel to split the retaining wall blocks along the center groove if they did not come pre-split from the factory. Splitting the blocks gives them a natural, rough stone appearance.
- 4
  
  Check for level blocks from every angle as you build.
  
  Set the first row of blocks into place. Press each block heavily into the gravel base, and tap the top of each block with a rubber mallet to help settle the block into the gravel. Use a carpenter's level to check that each block is level before moving on to the next block. Fill in uneven areas with sand to ensure the first row is completely level. The first row establishes the strength, shape and structure of subsequent blocks, so take your time to get it right.
- 5
  
  Offsetting the blocks adds an extra design element to the wall.
  
  Sweep dirt and debris off the top of the first row of blocks with a hand-held sweeper. Add the second row of blocks squarely on top of the first row. Offset the first block of the second row by a half a block to stagger the joints for visual interest and increased stability. Continue to check each block installation to ensure it is level.
- 6
  
  Apply adhesive or mortar with a trowel for even coverage.
  
  Backfill behind the wall as you install each row of blocks. Pour fine gravel, sand or dirt behind the retaining wall for stability and proper drainage. Secure each row with construction adhesive or a thin mortar base for added strength and stability.

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