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Build a Retaining Wall System
It can add functionality, beauty and safety to your home

Level of difficulty: Intermediate

Retaining walls are a great way to create a more useful, beautiful, and sometimes safer landscape around your home. If, for example, your back door opens right up to a steep hill (up- or down-sloping), robbing you of level area for a patio or lawn, build a single, tall retaining wall across the yard a distance from the house and level the terrain between the house and the wall. Or, if you prefer a terraced landscape for plantings and gardens, tame a too-steep slope with two or more low retaining walls.

Depending on the scale of the project, you may be able to make the cuts into the hillside and redistribute the soil by hand, or you may need a machine. If you're feeling adventurous, rent an easy-to-operate mini-backhoe/loader; otherwise, hire an excavator.

While nothing can match the beauty of a finely crafted mortarless stone wall, building one is far beyond the skill of most homeowners and even masons. However, the average do-it-yourselfer can easily build a segmental retaining wall system using dry-stacked precast concrete masonry units instead of stone. Concrete and masonry supply outlets stock a variety of styles, but most brands have a rough "stone-like" texture on the face and are designed either to interlock or to be pinned together.

Materials List:

Long-handled shovel 2-ft. 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 Wheelbarrow Hand-drilling hammer Crushed stones Torpedo level Tamper (rental item) Geogrid reinforcement Long straightedge

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.