How to build a retaining wall

A retaining wall holds back earth materials such as rock and dirt, and supports and stabilizes them from moving downward or sliding down hills in erosion or other downward movement. Structures that hold back water may be considered retaining walls as well.

Retaining walls are usually made of stone, brick, vinyl, steel, metal, concrete, or wood. Railroad ties used to be implemented in retaining walls, but out of environmental concern, they no longer are. The walls may be found at beaches to keep dirt behind sand from moving.

While one-piece concrete or wood walls used to be most popular, now segmental walls are used more often because they're cheaper, easier and more environmentally friendly.

The most important consideration in building a retaining wall is the lateral earth pressure, smallest at the top, because they will move the wall if not addressed correctly.

Thanks to guidance from Truevalue.com (http://www.truevalue.com/content/projects/ContentView.aspx?sec_id=4&subsec_id=58&con_id=1102), we can see how to go about building a retaining wall step by step!

Materials List:

• Long-handled shovel
• 2-ft. level o Pickaxe, mattock (digging tool), and digging bar, as needed
• Carpenter's or framing square
• Tape measure o Retaining wall system block
• Wooden stakes
• Work gloves and heavy work boots
• Mason's twine o Back support o Line level
• Brick chisel
• Wheelbarrow
• Hand-drilling hammer
• Crushed stones
• Torpedo level
• Tamper (rental item)
• Geogrid reinforcement
• Long straightedge (a straight 2x4)

Remember this project can be costly!

1. Excavate and Lay Out: Start with a preliminary excavation to create a wide, level area where the wall is to be located, and grade the area on the downhill side of the wall. Then drive stakes a few inches to the downhill side of the wall location; stretch a level mason's twine between the stakes about 6 inches above the grade. Hook a line level over the string and move one end of the string up or down as needed.

2. Excavate Footing Trench: Excavate an 18-in.-wide, 6-in.-deep trench on the uphill side of the line. Fill the trench with crushed stones and rake it level. Then use a tamper (you may want to rent this rarely used hand tool) to compact the stones. Place a 2x4 straightedge on edge and place 2-ft. level on it to verify the gravel footing is level.

Tip: If you prefer a gently curving wall, lay down a garden hose or length of rope to guide your excavation instead of stakes and string.

3. Lay the First Course: Place the first concrete unit on the stones a measured distance from the string. Use a torpedo level to verify that the block is level front-to-back and side-to-side. Similarly place the remaining block for the first course, using a 2-ft level to verify the stones are level and in line with each other.

Caution: Wear heavy work gloves and sturdy boots to protect your hands and feet from injury. Avoid injuring your back when lifting heavy stones. Always bend at the knees and use your legs, not your back, to lift. Consider buying an elastic back support for added support.

4. Cut a Starter Block: In order to stagger vertical joints, the first block in the second course (and in every other even course: fourth, sixth, etc.) must be cut in half. To make the cut, use a brick chisel and a hand-drilling hammer (small sledge) to score a cut line all around the block. With patience and when the scored line is deep enough on all sides, the block will break on the line.

5. Lay the Second Course: Simply stack the block for second course on top of the first one, beginning with the half block. Step each course back a little as directed by the manufacturer. Typically you will want the wall to slope backward (called batter) 1 inch for every 12 inches of height.

6. Backfill as You Lay Block: Backfill and tamp the soil behind the wall as it rises. Reinforce the earth behind the wall by placing a layer of a material called a geogrid as you backfill. Typically all systems will call for this reinforcing material for walls over a certain height and will specify how and where it is to be installed. Repeat Steps 5 and 6 for subsequent courses.

7. 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 even slope slightly down for at least a few feet.

8. Plant and Enjoy! Spread mulch, sow seed, lay sod, and plant your garden - or lay your patio - and enjoy.

Written by Roy Barnhart, home improvement expert, Fairfield, CT.