If you built a retaining wall at the same time your new home was going up, it undoubtedly has an important function. Transforming a deep-set incline into usable outdoor space for patios, driveways, gardens, and the like is certainly for what it was named. If the natural terrain wasn’t held back, the area would likely be prone to mini mudslides every time it rained.
Some homeowners incorporate terraced retaining walls into focal points for landscaping purposes. Long, running walls down the length of a garden or yard create a beautiful effect all on their own. Couple them with greenery interspersed with dramatic bursts of color and the end result may truly be considered mesmerizing.
Looks can be deceiving
Building a wall appears to be a fairly simple process, however, building a retaining wall requires a great deal of forethought in order for it to keep its shape. And, we aren’t referring to the terraced design either.
According to an article on Bob Villa’s website, a four-foot-tall retaining wall that is fifteen feet in length has to support up to twenty tons of soil pressure. That’s nothing to sneeze at! Imagine the force of the pressure of the soil pushing the wall down during the rainy season. Eesh. That could certainly be a labor-intensive cleanup! And if it comes down within feet of your home—
Mudpocalypse!
We’ll share a little rule of thumb for any future design purposes. With every additional foot of height, the pressure of the soil pressing against the wall increases substantially. If you miscalculate, the above disaster is far more likely to become a reality. To avoid it, we’d suggest hiring a professional to design and complete the job if you plan to build a retaining wall that’s over four feet tall.
Still jobs for the DIY crowd
Do-it-yourself construction is all the rage… especially when considering the way inflation is impacting our society! If you have a working knowledge of construction, building shorter retaining walls isn’t out of the question.
Some small retaining walls can be built over a weekend. Depending on the number of hands you have on the project, it may stretch into two. Especially, if there is additional landscaping involved. We might suggest focusing on the wall building first. Then, after it’s completed, take a final look at your garden design and make any tweaks that might come to you before you go shopping.
Whether you build it or not
It’s a good idea to check in with local authorities before the project begins. Retaining walls impact the natural flow of rainwater. This could cause an issue for surrounding neighbors. It may be necessary to obtain a permit before you can begin construction. Some communities request to see your building plans for the retaining wall and, even, schedule a property inspection to ensure your wall addition won’t cause drainage problems for others.
It’s also a good idea to call DigSafe (811) as a just-in-case measure even if you don’t plan to do any digging. DigSafe is a nationwide service that notifies local utility companies that you plan to dig in the area. Someone should be out within a matter of days to mark any buried utility, gas, or water lines.
Once that’s done and you—or your contractor—have the permit—if required—in hand, you can get started.
Choosing the material
If you work with an experienced contractor, they can guide you in making your material choice if necessary. There are a number of options which include pouring concrete walls. Homeowners have the ability to take this a step further and have the concrete designed to appear as stone, rock, or tile.
DIY enthusiasts would do better using manufactured blocks because they’re designed specifically for building retaining walls. They have a locking flange along the bottom edge that locks the blocks together securely. These gray or earthy-toned blocks are available in either textured or smooth surfaces. You’ll find them at any home improvement store, most garden centers, and can purchase them online as well.
Firm foundations
In order for your wall to be strong and secure, first you must lay out a stable foundation. If your retaining wall is under four feet, digging a trench deep enough to fill with three inches of crushed rock should keep the wall from shifting and settling. The depth of your trench must be in correlation with the height of your wall. Online calculators can help you figure out the math so you won’t fall short.
The first row of blocks must be installed perfectly level. Check and double-check. Failing to nail this step won’t bode well for the finished result. Drawing attention to the space because it’s lopsided and unattractive isn’t in the game plan.
Onward and upward
As you progress to subsequent rows, stack the blocks at a slightly backward slope. Doing so allows the wall to lean into the soil that it’s retaining. This makes it less likely that the soil will push against the wall in such a way that it might eventually give way.
We’ll note here that the locking flange on the bottom edge of the retaining wall blocks is designed to lock into position a bit behind the lower block. This creates a barrier that prevents the top blocks from being pushed forward.
Ward off groundwater
Accumulating groundwater is your wall’s worst enemy. The water saturates sandy soil eventually making it become unstable. Stop a problem before it starts by making drainage provisions as you build your retaining wall. Backfilling the space behind your blocks with crushed stone and installing a flexible perforated drainpipe, also known as a drain tile, at the base of the wall allows a place for groundwater to escape. Run your pipe to the end of your wall and it will drain away from the edge.
You can camouflage the ends of the drainpipe by covering them with crushed stone.
Polish off the job by backfilling the rest of the space behind the base layer of rocks with either sand or pea gravel. Both allow water to filter through them and reach the perforated drain pipe beneath. Tamp down the surface of the fill every six inches or so to ensure the surface is packed tightly.
As you slowly take a moment to straighten up after inspecting the camouflaged ends of the drainpipe, take a moment to admire that new wall. Whether you built it or not, the feeling that envelops you is going to be worth savoring a moment.
Maybe two.