Hardscaping & Landscaping Blog

How to Build a Retaining Wall

                Whether you would like to create a flat surface out of a sloped yard or create a raised garden to grow your favorite plants or vegetables, building a retaining wall is as smart as it is useful. There are varying options when it comes to what material or style you would like to achieve, but in this post we will focus on the basics to give you a better understanding of what our process involves. Though the thought of enhancing your yard with such a project may seem daunting, please don’t let that deter you.  Instead, remember that a sturdy landscape retaining wall will completely transform your landscape, turning it into a space that can finally be used to its fullest potential.

                To begin, we create a solid foundation for your retaining wall. We start by digging out a trench that is fourteen inches deep and between eighteen and twenty-four inches wide. This will allow us enough room to both create a strong base and bury the first course of blocks for your wall. We do this because a solid support system is necessary to keep your wall standing upright over time. After the trench is dug we fill the bottom with eight inches of class five gravel and compact it down. We use this material because it is easily compacted and helps to drain water away from your base. The gravel also aids in leveling out the ground beneath your wall and lends itself to supporting a more solid structure.

                After we lay down the first course of blocks we check again that the base of the wall is level. This step is imperative as we need a level base in order to build a level wall. Once we know the first course is level we begin to stagger the landscape blocks and build upwards. We cut one of the blocks in half, and place one half at each end of the wall. We do this for every other course, and this way the joints between the blocks of each course will naturally be staggered from the courses above and below. However, we do not simply build up your wall vertically. The soil behind a retaining wall exerts a great amount of pressure and to counteract this force we step the blocks back towards the soil with each course. The blocks we use have a special feature, a lip at the back of the block which catches against the block below it. In this way we use the pressure from the soil behind the wall to our advantage, as it will now push against the lip of one block and hold it in place against the block below. To finish the blocks we glue down a final course of cap stones, forming a small lip and creating an aesthetically pleasing wall.

                Next, we fill the remaining cavity behind the retaining wall with some of the previously dug up native soil and tamp it down. We then put down a layer of washed rock extending twelve inches behind the wall. Unlike soil, the washed rock will not retain any moisture, meaning that it will not expand and push against your wall in the future. It will further serve to drain any moisture down towards our final critical feature, the drain tile. The drain tile is a perforated tube that runs along one of the lower courses and is sloped down and away from your retaining wall. Once the drain tile is in place we cover it with another twelve inch wide expanse of rock, all the way up to a six-inch gap to the top. The rock is topped off with more of the native soil, thereby giving you the choice to plant or sod over the top of your retaining wall.

                We know that water means movement, and if it is not directed away from your wall, that water will push its way through; along with any soil it can pick up on the way. If left without a place to go water will move the ground around your retaining wall, and over time, even the wall itself. The drain tile will discourage this, and in order to prevent the drain tile from clogging with dirt or debris we cover it with what we call a “sock,” essentially a mesh-like fabric that allows water to seep through but prevents the soil from following. This entire process functions to channel any moisture out of the soil and down to the drain tile, where it is whisked away from your retaining wall.

                Keep in mind that these steps are really just a guideline for what is involved with building a landscape block retaining wall. Before any of the actual construction can take place we make note of several key elements that will determine the scope of work involved with your project. Factors such as slope, size, and soil content are all major influences on your project, not to mention any city or state building requirements.  Rest assured that our experience gives us the skill necessary to provide you with such solutions when constructing your retaining wall. Whether this means incorporating geosynthetic fabric or soil correction techniques, we will make sure to build you a sound, safe retaining wall. In fact, we go above and beyond industry standards to do so, because making our customers happy is what makes us happy.

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