How to Do a Retaining Wall With Bricks

Steel rebar serves as the spine of a brick retaining wall.

As the purpose of a retaining wall is to hold back dirt, the wall needs to be able to resist severe pressure. Although brick masonry is sturdy, one or even two layers of brick are not enough to stand up to this demand. The brick must be based on a solid foundation and reinforced with steel rebar. In addition to mastering basic masonry, this task requires learning how to pour concrete and work with probably unfamiliar power tools.

Things You'll Need

• Sketch pad
• Pencil
• Shovel
• Saw
• Measuring wheel
• Stakes
• Hammer
• Gravel
• Iron rake
• Hardboard
• Nails
• Concrete mix
• Wheelbarrow
• Float
• Mortar mix
• Trowel

Instructions

Preparation

1. Sketch out the design of the concrete footing, rebar placement and brick wall. The rebar runs up between two separate brick walls, with one rebar placed for every 3 feet of wall. The width of the concrete footing is at least twice the width of the retaining wall. Assuming 4-inch wide bricks and 1/2-inch thick rebar, that means a minimum of 17 inches in this example. The depth of the trench is equal to how much footing extends past the wall placed on top of it, in this case 4.25 inches.

2. Shovel out the hill slope the retaining wall will retain to clear the work area.

3. Use a piece of timber to match the width of the footing (17 inches in this case) and walk down the perimeter of the work area with a measuring wheel. Mark out the trench for the concrete footing by planting two stakes every 3 feet on opposite sides of the proposed trench, using the timber as a spacer.

4. Dig the trench. Add an extra 6 inches to the depth, so you can lay down a gravel foundation and bury the trench later. That makes the trench in this example 10.25 inches deep.

5. Pour gravel into the trench. Smooth the gravel out into an even, 3-inch thick layer with an iron rake.

6. Bend the steel rebar into "L" shaped rods with the rebar bender. The base of the "L" needs to match half the width of the concrete footing, reaching from the middle to the edge of the footing. In this example, that calls for a 8.25-inch base.

Concrete Footing

1. Set hardboard along the sides of the trench to form a mold for the concrete. Fasten it to the stakes along the perimeter with a hammer and nails. Tack successive pieces of hardboard together by driving a nail through both ends at an angle.

2. Mix concrete in a wheelbarrow and dump it into the trench. Keep mixing and dumping concrete until you have filled the trench up to 3 inches from the top, spreading the concrete with an iron rake.

3. Plant rebar into the concrete as indicated by the stakes. Check the plumbness (vertical straightness) of each rebar with a level, adjusting the placement as necessary.

4. Smooth out the concrete footing with a float and allow it to harden for at least 24 hours before proceeding.

5. Break down the hardboard mold once the concrete footing is hard.

Laying Brick

1. Mix up enough mortar in the wheelbarrow for 30 minutes of work. Limit each batch to roughly this amount so as to avoid having the mortar harden before you can use all of it.

2. Trowel out an even, 1/4-inch thick bed of mortar onto the concrete footing, along one side of the rebar. The bed should be slightly thicker than the bricks (a little more than 4 inches in this case).

3. Butter the ends of the first brick with a 1/4-inch thick layer of mortar, using the trowel. Lay the brick into the bed of wet mortar, alongside the rebar. Tap the top with the butt of the trowel to settle the brick into place.

4. Lay a full course of bricks. Repeat Steps 2 and 3 to lay another course of bricks onto the other side of the rebar.

5. Spread a fresh bed of mortar atop the first course of bricks and lay down a new course. Alternate laying courses back and forth between the two sides of the rebar, building a wall on either side.

6. Connect the two walls with wall ties by setting the ties into the wet mortar, starting with the fifth course of the wall. Place one tie for every 3 feet of wall.

7. Bury the concrete footing by filling in the remaining 3 inches in the trench.

Tips & Warnings

• The rebar bender is a powerful and dangerous tool, so make sure you thoroughly understand its workings before bringing it home from the hardware rental store. Always wear a hard hat, safety gloves and safety goggles when using this machine.

References

• "Popular Mechanics: Home How To"; Albert Jackson and David Day; 1989
• How to Lay Brick: Laying Brick
• Popular Mechanics: 5 Secrets to Building a Better Shed