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Retaining walls can be the perfect solution for turning a sloped area into a usable outdoor space. They can add style and beauty to your yard while reducing the erosion of valuable soil. However, constructing a reliable concrete block retaining wall can be more complex than it first appears. Retaining walls with the structural integrity to hold tons of pressure from soil and water, season after season, requires thoughtful planning and an understanding of a few basic principles.
This guide will give you the background to create a basic retaining wall. For bigger projects or if you’re interested in a precast retaining wall or gravity retaining wall, we recommend hiring a landscape architect or licensed landscaping contractor instead of a DIY solution.
If you construct your own concrete retaining walls, use the following dos and don’ts to help ensure your wall will remain standing for years.
Before stacking blocks, take detailed measurements of the area where you plan to build the wall. You’ll need the length of the wall, the wall height, and an estimate of how much soil the wall will need to hold. All of this information will go into deciding what materials you need and how much.
Retaining walls need a lot of structural strength. They need to hold back tons of soil pressure. The taller the wall, the more pressure it will need to withstand. Some DIYers can handle the construction of a four-foot-tall retaining wall, but anything taller can become structurally unstable unless it’s designed and constructed by a professional.
If you’re determined to DIY, separate tall walls into smaller, tiered retaining walls.
Retaining walls can change drainage routes for water in your yard and surrounding areas. Since this could affect your neighbors, your state may require that you obtain a building permit before beginning construction.
Also, you will need to dig down into the soil several inches to create the foundation for your wall. As with any digging project, contact DigSafe at 811 so they can arrange for the utility companies to come out to your property and mark where their buried lines are. That way, you can avoid them while you build your wall.
Different types of retaining walls come in various materials. Professional landscapers and contractors can create a retaining wall out of reinforced concrete, precast modular retaining wall systems, wood, and other materials. They can even use the weight of the hill to provide more stability with a gravity wall. Any of these are good options if you work with a contractor.
If you prefer to go the DIY route, keep things simple and stick with block retaining walls.
Concrete block retaining walls are the simplest and most effective choice for most resting wall needs. Concrete block manufacturers create blocks specifically designed for retaining walls. These blocks, sometimes called hold-a-hills, have a protrusion at the bottom that helps guide them into position and hold them in place. They help you construct your wall correctly and come in various colors and textures.
Before you begin staking up your wall, prepare a proper foundation to make your wall stronger. The depth of the foundation should be one-eight of the wall height plus three inches. In colder climates, you may need to dig deeper to get below the frost line.
Dig your foundation to the appropriate depth, then put down a three-inch thick base layer of crushed rock. Finally, ensure the foundation of your wall is exactly level before you begin stacking blocks. Any imperfections will be multiplied as the wall extends upward.
Your concrete block retaining wall should slightly slope back into the land it’s holding in place. That will give it better leverage for holding the heavy force of the soil and make your wall stronger. If you use concrete blocks designed for retaining walls, the interlocking protrusions will help you create the right shape for your wall.
Without proper drainage, water will build up in the soil behind your retaining wall. That will make the ground heavy and put a lot of pressure on your wall. Ensure the water can drain away from your wall by backfilling behind the base of the wall with crushed rock. Then install a drain using a flexible, perforated pipe or drainage tile.
Once you install your drain, backfill the base of your wall with sand and pea gravel. Backfill a little for every layer of block you apply. Tamp it down to create a tight, solid fit.
If you’re ready to begin prepping for your retaining wall project, contact the precast specialists at Harper Precast. They can help you determine the best materials to use for your yard’s specific needs. Contact Harper Precast today!
