DIY Concrete Retaining Walls

A properly installed concrete retaining wall will last a lifetime.

A hillside can be landscaped in different ways. Many landscaping choices are limited by the steepness of the slope and the local weather patterns. Prevailing winds and heavy rainfall can destroy a landscaped hillside before many of the plants have a chance to take root. One way to control erosion on a hillside is by the use of retaining walls. These barriers turn a hillside into a series of stepped, flat areas that will withstand the elements much better. A properly installed retaining wall will last a lifetime and add a whole new element to your landscape.

Things You'll Need

• Shovel
• Drill with ½-inch bit
• All thread rods (3/8 inch by 4 feet) with washers and nuts
• Circular saw
• Plywood sheets (5/8 inch by 4 feet by 8 feet)
• L brackets
• Hacksaw
• Rebar (5/8 inch by 10 feet)
• 8-pound sledge hammer
• Tie wire
• Tin snips
• Hand grinder
• Concrete delivery service
• Concrete vibrator
• Concrete float
• Work gloves
• Safety glasses

Instructions

1. Determine the location of your retaining wall. Dig out the hillside 5 feet back from the proposed outer facing of the retaining wall with your shovel. Dig the lowest level of the wall area 12 inches lower than the surrounding ground where the base of the wall will be located. Make this trench 36 inches wide while staying 2 feet from the embankment you dug out.

2. Stack your plywood and drill 4 rows of holes through the wood. Leave 8 inches of space between the holes in each row and 8 inches between rows. Twist a nut onto one end of a piece of all thread. Slide a washer onto the long end of the rod until it rests on the nut.

3. Slip the long end of the rod through matching holes in 2 pieces of plywood. Add another washer and nut. Adjust the nuts on both sides of the plywood to leave 3 feet of space between the inside of the pieces of plywood. Install another all thread assembly through each hole in your pieces of plywood.

4. Stand the plywood assembly vertically on the ground. Build matching plywood forms to place beside the first to run the entire length of your retaining wall. Cut 2 pieces of plywood 3 feet by 4 feet and attach them to the ends of the open form with your L brackets.

5. Cut 12 pieces of all thread 3 inches long with your hacksaw. Place 3 L brackets on each corner of the form. Drill holes through the plywood at each L bracket to use the small pieces of all thread to fasten the joints.

6. Place a piece of rebar inside the plywood every 12 inches along the length of your form. Drive the rebar 26 inches into the ground with your sledge hammer. Attach the rebar to the top row of all thread with tie wire. Lay 2 pieces of rebar horizontally across the top pieces of all thread inside of your forms. Twist the wire tight and cut the ends with your snips.

7. Call the concrete delivery company of your choice. Describe the type of structure you are building along with the dimensions. Listen to their suggestions as to the type, strength and consistency of the mixture you should use depending on your geographic location, time of year and availability of materials. Arrange delivery of your concrete.

8. Pour the concrete from the delivery truck into your forms. Start at one end and pour a foot-deep layer of concrete along the entire length, reverse direction and pour back to the other end. Have an assistant follow along behind you dragging the concrete vibrator slowly through the mixture to remove air bubbles. Pour in 12-inch layers until the forms are full. Do not stop between layers. Continue the pour until the wall is complete.

9. Smooth the top of the wall with your concrete float every hour for 8 hours. Allow the concrete to cure for 2 weeks. Remove your forms. Cut off the exposed ends of the all thread. Shovel the dirt from your original excavation behind the retaining wall to back-fill the gap.

Tips & Warnings

• Work gloves and safety glasses should always be worn when working with hand tools and pouring concrete.

References

• Concrete Network: Poured Concrete Retaining Walls