The key to establishing a sound retaining wall is in the way that it is constructed. Not all retaining walls are built the same. The higher you build them the stronger they need to be. Of the many unique materials that retaining walls can be made of, concrete is the strongest way to erect a retaining wall. Not many of us are going to build a dam, but the same principle applies. When you have built a retaining wall, the last thing that you want to happen is to fall and tip over. If you want to build a concrete retaining wall, it has to have a proper foundation to rest on. A legitimate rule of thumb for building a foundation is that it should be at least 8'' thick and 1/2 as wide as the wall is tall. This means that if your retaining wall is 6' tall, it would have a footing of concrete to rest on, measuring 8'' inches deep and 3' feet wide. Start by digging a trench into the ground that is about 6 inches wider then the foundation is wide. Next, develop a form to hold the concrete in place. Place a minimum of two number 5/8 rebar down the length of the foundation. Tie upright rebar on a 2' center to the rebar. This should run horizontally in the footing.(Make sure to bring the upright rebar, up and out of the footing about 1 foot from the front of the retaining wall.) Never place the retaining wall to the back side or center of the footing. Always place the concrete retaining wall to the front of the foundation. This way, you create a balance of pressure as the dirt or backfill presses out on the retaining wall. It also pulls it back as it presses down on the back side of the footing.
In the Seattle area, we get a bit of water that gets into the ground. This can cause trouble for even the strongest of retaining walls. For this reason, a good water release system is needed to cut the hydrostatic pressure on the backside of the retaining wall. The best way to do this is to create a trench in the backside of the retaining wall. Place a drain pipe slightly above the footing and fill the trench with gravel. Place a filter fabric over the gravel-filled trench. This will keep the dirt from filtering down through the gravel and clogging the drain pipe. This system should be used if your retaining wall is 4 feet high or higher if there is extra groundwater, I will use this system on even lower retaining walls. One other way to release water from behind a shorter retaining wall is to follow the first two steps of creating a trench and filling it with gravel but don't put in a drain pipe. Instead, drill or leave small holes through the base of the retaining wall this will slowly release any water that is behind the wall. No matter which method you chose, a fabric filter should always be used over the gravel behind the retaining wall. Now, you can fill over the gravel with topsoil and conceal the drain system.
Not all concrete retaining walls have to look like stark dull gray walls. We have built many concrete retaining walls that are beautiful to look at. They are an asset to the landscape that they hold in place. Try an acid stain on the outer side of the concrete wall. Add a blend of color acid stain, this creates a pattern that will blend in with the landscape and not stick out like a big gray wall. A coat of stucco can also be applied to a concrete retaining wall to create not only colors but also different types of textures. Cultured stone can be used to beautify any concrete wall. This can make any wall look and feel like a beautiful stone wall in the landscape. If you have any area that needs to be retained, a concrete retaining wall is an excellent way of doing it with little or no maintenance. If you have any area that needs to be repaired, there are many ways to make it look like new without even replacing the existing concrete. Please visit our beautiful picture gallery to view some of our retaining wall projects.