If you’re an experienced do-it-yourselfer, you’ve likely worked with a variety of materials to build various types of retaining walls. You might have even constructed a wall to create a raised bed garden or an outdoor patio. But have you built a retaining wall in order to create a walkout basement? If not, this article is for you! Read on to learn how to level the ground, determine the shape and location of your wall, and construct it so that it’s structurally sound.
Use treated lumber for the foundation to prevent rot and decay.
The foundation is the first part of your retaining wall. It’s important to use treated lumber for the foundation because it’s resistant to rot and decay, which can affect the structural integrity of your walkout basement.
To begin constructing your retaining wall, you will need:
- Lumber (treated 4x4s)
- Cinder blocks
- Concrete mix or mortar mix (see below)
Place a tarp on the ground to keep it clean.
Now that you’ve got your wall laid out, it’s time to start building it. Before you begin, however, make sure to set up a tarp on the ground under where your wall will be so that soil and dirt don’t end up everywhere.
You’ll want a tarp that’s big enough to cover the entire area that needs leveling, but not so big that it would get in the way of your shoveling and digging.
If there are areas where dirt is too high or unleveled—like near trees or bushes—you can use smaller tarps to cover those spots individually. This will keep them out of the way while still keeping them clean and dry as well.
Place landscape fabric over the tarp to prevent grass, weeds and other plants from growing through the retaining wall.
The next step is to cover the entire bottom of your retaining wall with landscape fabric. This woven fabric is similar to burlap and can be purchased at local hardware stores or online. You should use landscape fabric to prevent weeds from growing through your new walkout basement retaining wall. It is not a substitute for grass, soil, or mulch—it’s simply a barrier that keeps plants from invading the surface area of your retaining walls.
Dig 6-inch-deep trenches around the area where you will build the retaining wall.
Once you have determined the slope of your yard and how high you want your retaining wall, it’s time to dig trenches for the backfill. The width of each trench should be 12-18 inches wide and 6 inches deep. The trench should be at least 6 inches away from your house, as well as any existing concrete or masonry foundation walls.
Lay foundation gravel into the trenches and tamp down with a hand tamper tool.
To ensure the foundation is level and solid, you will need to take some time to carefully tamp down the gravel. Tampers are tools that use leverage to press material into place. You can use various types of tampers for different materials: a flat tamper for concrete, a round vibrating tamper for sand or gravel and a hand tamper tool for your garden bedding.
To use a hand tamper tool, place it at an angle and push down with your body weight until you hear it click into place on top of the gravel. Make sure there are no gaps between pieces of gravel before moving on to another section; otherwise, water can seep through from below and cause further issues.
Line up pressure treated lumber along the foundation trench, keeping it level using a carpenter’s level.
Repeat the process until you’ve lined up enough pressure treated lumber to fill in the entire foundation trench. Be sure to keep each course level from side to side and end-to-end. This will ensure that your retaining wall is strong and sturdy, because any gaps will cause weak points in your structure.
Drill holes in each piece of timber on an angle to allow for drainage. This prevents rain water from pooling behind your retaining wall, which will cause it to fail. You can use a 1/4-inch-diameter drill bit to make pilot holes for drainage. Drilling through wood fibers at an angle creates a wider hole than drilling straight through wood fibers. Use three rows of pilot holes for each piece of timber in your retaining wall base. Drill a row of holes every 6 inches from side to side and from end to end on each piece of lumber as you lay them out in your foundation trench.
Drill holes in each piece of timber on an angle to allow for drainage. This prevents rain water from pooling behind your retaining wall, which will cause it to fail. You can use a 1/4-inch-diameter drill bit to make pilot holes for drainage. Drilling through wood fibers at an angle creates a wider hole than drilling straight through wood fibers, so this is the best way to ensure that water drains freely away from your retaining wall. Use three rows of pilot holes for each piece of timber in your retaining wall base: one row every 6 inches from side to side and another row every 6 inches from end to end on each piece of lumber as you lay them out in your foundation trench.
Now you know the best way to build a retaining wall for your walkout basement. Building a retaining wall is not an easy task. However, after reading this tutorial, it should be much easier for you to complete this project on your own. The cost of building a retaining wall will vary depending on the size and complexity of the structure, as well as where you live.