How to Build a Concrete Block Retaining Wall

A concrete block retaining wall is a sturdy and attractive solution for controlling soil erosion, creating terraced gardens, or leveling a sloped yard. With the right planning and techniques, you can build a durable retaining wall that enhances your landscape. Here’s a step-by-step guide on how to build a concrete block retaining wall like a pro.

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2/28/20252 min read

a diagram of a brick wall with a picture of a brick wall

1. Why Build a Concrete Block Retaining Wall?

Erosion Control: Retaining walls prevent soil erosion on sloped landscapes.
Aesthetic Appeal: They create visually appealing terraces, garden beds, and leveled yard areas.
Structural Support: They provide necessary structural support to keep soil from shifting.

2. Tools and Materials Needed

Tools:
- Shovel and wheelbarrow
- Level and measuring tape
- Mason’s string and stakes
- Trowel and masonry hammer
- Concrete mixer (optional) or mixing tub
Materials:
- Concrete blocks (hollow core for reinforcement)
- Rebar (for structural reinforcement)
- Mortar mix
- Gravel (for base and drainage)
- Metal lath (for mortar-filled cores)
- J-bolts and sill sealer (if anchoring a wooden top plate)

3. Planning and Design

Determine Wall Height and Length: Measure the area and calculate the number of blocks needed. For walls over 4 feet high, consult an engineer for safety.
Check Local Building Codes: Permits may be required for retaining walls over a certain height.
Excavation and Drainage: Proper drainage is crucial to prevent hydrostatic pressure, which can cause wall failure.

4. Prepare the Foundation

Excavate the Base: Dig a trench at least twice as wide as the blocks and deep enough for the gravel base and the first layer of blocks (about 6-8 inches deep).
Add Gravel Base: Fill the trench with 4-6 inches of gravel and compact it using a tamper. Ensure the base is level.
Lay the First Course: Place the first row of concrete blocks on the gravel base. Check for level and alignment.

5. Build the Wall

Stagger the Joints: Offset each row so that the joints between blocks don’t line up, increasing stability.
Insert Rebar: Place vertical rebar into the hollow cores for reinforcement. The rebar should extend into the footing and rise above the top course.
Fill Hollow Cores: For added strength, fill the hollow cores with concrete or mortar mix.
Add Metal Lath: Insert metal lath into mortar-filled cores for added structural support.
Mortar Application: Apply mortar between each block layer using a trowel for a secure bond.

6. Finishing Touches

Cap Blocks: Install cap blocks on the top row using construction adhesive or mortar for a finished look.
Backfill and Compact: Backfill behind the wall with gravel for drainage and compact it firmly.
Optional Wooden Top Plate: If adding a wooden top plate, anchor it using J-bolts embedded in the mortar-filled cores.

Need Professional Help?

Building a concrete block retaining wall requires precision and the right techniques. If you need assistance or want a professional finish, contact ProHands Handyman. We provide expert retaining wall construction to enhance your landscape.

📞 Call or text: 818-401-7766
📍 Serving Glendale, Burbank, Pasadena, and surrounding areas.

Contact us today for a free estimate and professional installation!