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How To Build a Retaining Wall

A retaining wall is a great way to differentiate space in a yard. Here's how to build one.

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building a retaining wall Watch Video
  • Time

    Several Weekends

  • Price Range

    $2,500 - $5,000

  • Difficulty

    Moderate to Hard

Highlights:

Step 1: Calculate the Materials Needed

This product is sold by the square foot. To determine the square feet needed, multiply the length of the wall by the height. Remember not to forget the block that will be below grade. This wall is set into place using pins to join the courses of blocks together.
To determine the number of pins needed, use the following formula:
(# of non-cap courses – 1) x Lineal feet of wall = number of pins needed.
To determine wall caps needed, use this formula:
Total lineal feet / 1.25 = Wall Caps

Step 2: Prepare the Footing for the Wall Installation

Dig a 15" wide trench that is between 5" to 10" below the grade. As a rule, bury 1" of block for every 8" of exposed block. Compact the footing. Add 4" of 1/4" modified stone. Compact again.

Step 3: Begin Laying Blocks

Install the first layer of block by placing the units on the prepared base (Image 1). Be sure that the narrower slot on the block is on the top (Image 2). These blocks come in various sizes. Use a combination of sizes for the first course of blocks. Level the blocks from front to back and side to side with a dead blow hammer. Use your level to make sure everything is in its right place. Use your string line to assure the wall is straight.

Step 4: Continue Building the Wall

After your first course is laid, you can begin building your wall. Place the next and each additional course of block so that each block bridges two units below in a running bond pattern. Avoid having a vertical line span two layers of block. Install pins in corresponding slots as you build the wall. Make sure the flag of the pin is oriented to the wider part of the block.

install pins in corresponding slots

Step 5: Add the Caps

After installing your final course of wall block, attach wall caps with a high strength flexible concrete adhesive. Make sure each cap hangs between 3/4" or 1" over the edge of your wall.

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