How Do I Build Tiered Retaining Walls on a Hill?

Preparing the Base

• 1

  Measure the height of the masonry block with which the wall will be built. Dig a trench one-tenth of the height, plus 4 inches, with a spade in front of the hill. If each masonry block is 10 inches tall, dig a 5-inch trench. The width of the trench -- front to back -- should match the depth of the masonry block – front to back.

• 2

  Cut strips of landscape fabric with a utility knife to fit inside the trench. The landscape fabric should cover the bottom and sides of the trench. Lay the strips of landscape fabric inside the entire length of the trench.

• 3

  Cut lengths of 4-inch perforated PVC pipe to a length that is 1-inch longer than the width of the trench with a pipe cutter. If the trench is 8 inches wide, cut sections of PVC pipe that are 9-inches long. Cut one section of pipe for every 3 feet of trench length.

• 4

  Insert the PVC pipe sections in the trench. Align the front of the pipe with the front of the trench and curve the back of the pipe up the back of the trench.

• 5

  Pour gravel on top of the landscape fabric and pipes until it reaches a depth of 4 inches. Level the gravel with your hands. Set a leveling tool on top of the gravel to ensure it is level.

• 6

  Set one masonry block in the middle of the trench. One inch of the masonry block will be below ground level, inside of the trench. The remainder will be above ground. This will be true for all masonry blocks used in the base layer.

• 7

  Set a leveling tool on top of the masonry block. Tap the top of the block with a rubber mallet to set the block into the gravel. Level the block before adding the next.

• 8

  Fill the trench with masonry blocks. Work from the middle out, toward the ends of the trench. Align each block so the edges touch. Tap each block with a masonry hammer to set it into the gravel and use a leveling tool to keep it level. If the wall is curved, each block will have to be cut.

Cutting Masonry Block

• 9

  Put on a pair of protective eye goggles.

• 10

  Draw a line on the top of the masonry block with chalk where it needs to be cut.

• 11

  Hold one side of a squaring tool on top of the block so the other side extends down the side of the block. Align the squaring tool with the chalk line. Extend the chalk line down the side of the block. Repeat all the way around the block.

• 12

  Lay the block on solid dirt. Don’t lay the block on stone, concrete or another block.

• 13

  Position the tip of a mason’s chisel on the chalk line.

• 14

  Hit the handle of the mason’s chisel with a rubber mallet. Tap the chisel lightly. You want to score the line to a depth of about 1/8-inch. Score the chalk line around the entire block.

• 15

  Position the tip of the mason’s chisel inside the scored line.

• 16

  Hit the handle of the mason’s chisel hard with a rubber mallet to break the block. It will crack along the scored line. Move along the scored line and drive the chisel into the block until it breaks apart.

• 17

  Chip away the rough edges with the claw of a mason’s hammer. The edges of the block should be smooth and fit neatly against the adjacent block on the wall.

Building the Wall

• 18

  Equip a caulking gun with a tube of masonry adhesive.

• 19

  Squeeze the handle of the caulking gun to apply three lines of masonry adhesive to the top of the middle block on the first layer. Don’t apply adhesive to the front 1/4-inch of the block.

• 20

  Set a masonry brick on top of the masonry adhesive so it is set back 1/8-inch. The retaining wall must be sloped toward the hill to prevent the weight of the dirt and water, from rain or sprinklers, from pushing the wall forward. Each tier must be sloped at least 1/8-inch.

• 21

  Tap the top of the block with a rubber mallet to set it into the adhesive. Use a leveling tool to make sure the wall remains level.

• 22

  Build the second layer of the wall, working from the middle out, cutting each block as you go. Apply masonry adhesive to the top of each block on the first layer as you lay each block for the second layer. Squeeze masonry adhesive onto the sides of each block as well. Don’t apply adhesive to the outer edges of the blocks on the ends.

• 23

  Fill the space between the second layer of the wall and the hill with impervious soil. Don’t pack the soil, let it fall loosely. Impervious soil is a fine-grained soil that is purchased at nurseries, hardware, home improvement and landscaping stores.

• 24

  Continue building the wall, layer by layer, until it reaches the desired height.

Leveling the Hill for the Next Tier

• 25

  Extend a tape measure from the first tier of the wall up the hill.

• 26

  Drive two wooden stakes into the ground, one on each side of the hill, at the location where you want the second tier to be built.

• 27

  Tie a mason’s line between the two stakes.

• 28

  Dig the earth from the mason’s line to the first tier of the wall so the dirt is close to level with the top of the first tier of the wall.

• 29

  Shovel the dirt into a wheelbarrow and remove it from the work site. Keep the dirt nearby; you may need it again.

• 30

  Pound the dirt with an earth tamper. Use a leveling tool to keep the dirt level. If you accidentally dug too deep in some areas, fill in the holes with some of the reserved soil and tamp it down.

• 31

  Build the second tier of the wall.

• 32

  Repeat this process for each tier.

• 33

  Cure the masonry adhesive for at least 72 hours before putting any weight on the walls.