How to Build a Retaining Wall
A retaining wall holds back earth materials such as rock, sand, dirt, and even water, and keeps them in place to prevent erosion or displacement. Retaining walls are usually made of stone, brick, vinyl, steel, metal, concrete, or wood. Railroad ties have been used, but not anymore due to environmental concerns. While one-piece concrete or wood walls used to be most popular, segmental walls are used more often, because they're cheaper, easier, and more environmentally friendly.
The most important thing to remember when building a retaining wall is the lateral earth pressure—it should be the smallest at the top, because the wall could move and be ineffective otherwise.
Thanks to guidance from Truevalue, we can see how to go about building a retaining wall step-by-step!
Materials You'll Need
- Long-handled shovel
- 2-foot level, pickaxe, mattock (digging tool), and digging bar, as needed
- Carpenter's or framing square
- Tape measure
- Retaining wall system block
- Wooden stakes
- Work gloves and heavy work boots
- Mason's twine
- Back support
- Line level
- Brick chisel
- Hand-drilling hammer
- Crushed stones
- Torpedo level
- Tamper (rental item)
- Geogrid reinforcement
- Long straightedge (a straight 2 x 4)
How to Build a Retaining Wall
- Excavate and Lay Out: Dig out a wide, level area where the wall will be, and grade the area on the downhill side of the wall. Drive the stakes a few inches into the downhill side. Stretch a level Mason's twine between the stakes about 6 inches above the grade. Attach a line level over the string, and move one end of the string up or down as needed.
- Excavate Footing Trench: Dig an 18-inch-wide, 6-inch-deep trench on the uphill side of the line. Fill the trench with crushed stones and rake it so it is level. Then use a tamper (you may want to rent this) to compact the stones. Place a 2 x 4 straightedge on edge, and place a 2-foot level on it to make sure the gravel footing is level. Tip: If you want a gently curving wall, lay down a garden hose or length of rope to guide your excavation instead of stakes and string.
- Lay the First Course: Put the first concrete unit on the stones a measured distance from the string. Use a torpedo level to make sure that the block is level. Put the remaining block for the first course, using a 2-foot level to make sure the stones are level and in line with each other. Caution: Wear heavy work gloves and sturdy boots to protect your hands and feet. Be careful when lifting heavy stones—always bend at the knees and use your legs, not your back, to lift. You may want to buy an elastic back support for added support.
- Cut a Starter Block: Stagger the vertical joints by cutting the first block in the second course (and in every other even course: fourth, sixth, etc.) in half. Use a brick chisel and a hand-drilling hammer (small sledge) to mark the block where you will cut. When the block is marked completely, it will break on the line.
- Lay the Second Course: Put the block for second course on top of the first one, beginning with the half block. You usually want the wall to slope backward 1 inch for every 12 inches of height.
- Backfill as You Lay Block: Backfill and tamp the soil behind the wall as it rises. Reinforce the earth behind the wall with a layer of geogrid as you do this. Repeat Steps 5 and 6 for the next courses.
- Complete Final Grading: Fill the trench on the downhill side of the wall with tamped crushed stones and spread topsoil up to the wall. Add topsoil on the backside of the wall until it is a few inches from the top. The grade behind the wall should be level or slope down for at least a few feet.
- Plant and Enjoy! Spread mulch, sow seed, lay sod, and plant your garden—or lay your patio—and enjoy.
Note: This was written by Roy Barnhart, a home improvement expert in Fairfield, CT.
This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.