One of the purposes of building a retaining wall is to prevent erosion, soil erosion in particular. Soil is eroded by wind, rain, and flowing water, but in your backyard it is most likely to be due to the wind and the rain. If your property has a slope or incline, building a retaining wall can prevent a buildup of mud or small rivulets coming down the slope and ruining your other landscaping. The retaining wall will act as a drainage regulator and channel water and mud where it will be less prone to do damage. Retaining walls can also be decorative and used as raised flower or vegetable beds. While a large retaining wall should only be constructed by an expert, building a small retaining wall in your backyard is usually a small one-person job.
Step 1 - Permit
Even though you may be building on your own property, you should check into your city building codes to learn if you need a permit to carry out the work of building a retaining wall.
Step 2 - Design
Before building a retaining wall, you need to design it first rather than bulldozing straight in and facing problems midway through the project. Using graph paper makes drawing to scale easier. Draw an aerial view of your yard and where the retaining wall will be situated. Once you have planned the location, you will need to determine the dimensions. Using another sheet of graph paper, draw a side view showing the foundations underground and add measurements. The first design will act as a rough guide and the second will be an unofficial blueprint.
Step 3 - Foundations
The secret to building a retaining wall that will last is a strong foundation. The general rule of thumb is that there should be 1 inch of wall underground for every eight inches above the ground. You will need to dig a trench for your foundation to be poured into; the trench should be the underground height plus five inches. The bottom of this trench should be filled with four inches of gravel and then a layer of bedding sand, which will be one-inch thick.
Step 4 - The Wall
You can now begin to build the wall out of retaining wall blocks. For a good sturdy wall, use retaining wall blocks that are all roughly the same size and shape. Make sure the joints between blocks are staggered, as this will add strength to the structure.
Step 5 - Drainage
As you are building a retaining wall, you need to take drainage into consideration. After you have placed the first row of wall blocks, backfill it with crushed stones and repeat until your wall is the desired height. When you get to the last row, add retaining wall caps to prevent water from trickling into the backfill.