How to Build a Retaining Wall
8 simple steps to installing a retaining wall
Most people think that learning how to install a retaining wall is a difficult process. Do yourself a favor and do it yourself! You will save a ton of money and probably even enjoy doing it! Retaining walls are great for making your lawn or garden more attractive. The most common uses for creating a retaining wall include: tree rings, flowerbeds, and even mail box posts.
Mandatory tools and materials needed: Level, Tape Measure, Stakes, Shovel, Safety Goggles, Tamper, Landscape Adhesive, String
Optional tools needed: Chisel, Landscape Fabric, Sledgehammer
Step 1: Design your retaining wall. There are literally hundreds of different kinds of retaining wall blocks to choose from. Some are very large, and some are very small. The most common blocks are 12" wide x 4" tall. However, the block's nominal dimensions usually end up being 11 and 1/2" wide x 3 and 1/2" tall. The easiest way to figure out your project is to draw out the dimensions you want on a piece of paper. Figure out exactly how many feet you will need lengthwise and how many feet you will need height wise. Most of the bigger home improvement stores will gladly estimate how many blocks you will need free of charge.
Step 2: Dig the trench for your retaining wall. Many people question how deep of a trench you need to build for your retaining wall. It all depends on how big your blocks are and how tall you want the wall to be. If you have a small to average sized block and only want the rows 1-3 blocks high you only need a 4" deep trench. If you have bigger blocks and want to go higher than 3 rows tall, you must have at least a 6" deep trench. Think of the trench as the foundation of your home. Keep the trench as flat as possible. Use the level to ensure it is completely flat.
Step 3: Prepare the base of the trench. Add 2 to 3 inches of paver base and press it down with a tamper. You must keep the paver base completely level. Remember the base is the most important part of the wall.
Step 4: Lay the blocks. Carefully lay your first row of block. Be very careful to ensure you have your blocks laid out exactly like you want them. As long as the ground and paver base were completely level, this should be a piece of cake!
Step 5: Fill the retaining wall. After installing each row of block, fill the backside with sand or dirt. Do this as you go so the dirt has time to settle as your building the wall. Whether you have 1 row of 5, this will make the project much easier.
Step 6: Adhere the top row. Many people enjoy putting a cap on their retaining wall to give it a finished look. A cap is not mandatory. However, if you choose to put a cap on your wall, you must adhere it with landscape adhesive. Landscape adhesive is similar to epoxy. The blocks will never come off again. You must use landscape adhesive on the top row to ensure its stability. Since the cap block is typically lighter it is much more likely to shift or even fall off.
Optional Tip 1: If you are using light retaining wall blocks or if you just want to guarantee that your wall is stable. Use landscape adhesive on every row of block. The only downside to doing this is that if you ever want to move the blocks it will not be possible.
Optional Tip 2: If you are building a tree ring or a retaining wall that has curves, you may find that the blocks have gaps. This can be very frustrating and unfortunately the only way to fix this issue is to cut the blocks. Many home improvement stores have block cutters that will make this much easier. However, if you want to do it the old fashioned way you will need to draw a line on the block, take a chisel, and hit it with a sledgehammer. The blocks will not break easy.