How to Install a Small Retaining Wall on an Uneven Slope

Place a wood stake in the yard where you want one corner of the retaining wall to sit. Measure out from the stake the length that you would like for the wall to be, such as 6 feet, and then place a second stake in the yard at this distance.

Measure the width of the building material, such as the railway sleepers or blocks, that you want to use for the retaining wall. Measure this distance out from each of the stakes that you have already placed in the yard and place a third and fourth stake directly across from the first and second stakes to create a rectangular shape. Tie strings between the stakes to make a visual representation of the wall's perimeter.

Dig a trench inside of the perimeter that you marked for the wall. Make the trench 12 inches in depth at the lowest point of the slope and dig as far down as necessary as you move up the slope to make the trench level across the bottom. If the highest point of the slope is 12 inches higher than the lowest point of the slope, for instance, you must dig down approximately 24 inches for the trench to sit level with the trench at the lowest end of the slope.

Add 1/4- to 1/2-inch gravel to the trench so that it fills the bottom 6 inches of the trench all the way across. Smooth the gravel down as evenly as you can by sight and then check the gravel by placing a 4-foot builder's level at one end. Make sure the bubble in the level appears in the center and then move the level along the trench, checking for level all the way to the other end.

Spread 1 inch of sand over the top of the gravel. Check the trench for level again and use a compactor to press the gravel and sand down into the trench. Check for level one last time and add sand where needed to make the trench even all the way across.

Lay a row of railway sleepers or blocks side-by-side all the way across the trench. If you intend to make a wall taller than two feet, or if your building materials are lightweight, use an appropriate adhesive, such as mortar, on the base of the wall and between each row. If the wall will be shorter than two feet and uses heavy materials, such as sleepers or stone blocks, you can dry stack the blocks.

Stack rows of the building material on top of each other, using an appropriate adhesive where necessary, until the wall reaches the height that you desire. Since you are building on a slope, different amounts of the wall will be exposed when you finish. In the case of a 12-inch height difference, for example, 3 feet of wall shows at the low end of the slope and only 2 feet at the high end.