How to Build an Interlocking Retaining Wall for Beginners

Retaining walls can hold a raised garden, prevent hillsides from erosion and give a yard a boost in ambiance. Traditionally, retaining walls were made by experts from poured concrete, or blocks and bricks stacked and mortared together. With interlocking blocks, even a beginner can create a good-looking wall. John Wagner from the "This Old House" website recommends that an interlocking retaining wall be kept under 3 feet high because the pressure of the soil and water behind it will be too great for a higher wall.

Shovel
Landscape fabric
Gravel
Carpenter's level

Instructions

- 1
  Dig a straight-walled trench the length of the wall, 4 inches wider than the width of the blocks and 1 foot below the frost line for your area.
- 2
  Hand tamp the soil down the length of the trench.
- 3
  Create a U-shaped lining for the trench with landscape fabric covering both sides and the bottom.
- 4
  Fill the bottom of the trench with gravel no less than 1/4 inch in diameter.
- 5
  Lay the first row of blocks along the trench, with the face of the block against the edge of the trench. Use a carpenter's rule as you add blocks to ensure that the layer of blocks is level from end to end. Adjust the gravel underneath to make this happen.
- 6
  Lay the PVC pipe on the gravel just behind the blocks.
- 7
  Add the next layer of blocks starting at the end with a half-block, and staggering the layout so that two blocks never meet directly on top of where the two blocks below them also meet.
- 8
  Fill above the PVC pipe with more gravel, up to the level of the second row of blocks.
- 9
  Continue to add more rows of blocks, staggering each row by starting with either a whole or half block. Backfill with the gravel until you reach the surface and continue the rows for the height of the wall. After each row, check the level to ensure that it remains correct. If the first row was correct, the following rows almost always will be correct, but it always pays to double-check.
- 10
  Top the final row with the manufacturer's capstone or other method they provide for a finished wall.

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Fences & Walls