Retaining walls are found around many homes, businesses and schools. But chances are, you’ve never really noticed them. Though they can be beautiful additions to a property, they serve a fundamental purpose: expanding your useable outdoor living space.
A properly-built retaining wall provides extra support for the additional architectural items on your property like your driveway, shed or patio, by preventing the land beneath them from sliding downhill. From a physics perspective, the wall battles the gravitational force of a hill, ensuring that the soil beneath these additions is stable.
Retaining walls provide additional benefits as well. By turning what was once a graded hill into a plateau, you’ll slow water runoff from your home and protect your yard from flooding in heavy rainfall. Instead of running straight down a hill, the flat area breaks the momentum of the running water.
Looking for a Contractor to Help?
Download Our Contractor Comparison Worksheet
Retaining walls also provide more usable space around your property, turning what was functionally difficult to use into a flat, friendly surface. With that space, you could create a garden, patio, or walkway. Or you could simply open up more of your yard for easy walking, playing or resting.
Unsure if you need a retaining wall or want to better understand how they’re built? This article will address these topics and explain what considerations are important before you begin building.
When do You Need a Retaining Wall?
There are several scenarios which could call for building a retaining wall. Let’s start at the top of the hill. When your home sits at the top of a hill, you won’t have to worry about flooding, but you may not have much room for gardening or entertaining. If you build several short retaining walls, you can create a few “steps” or terraces on your land to help you maximize the usable flat space on your property. And as we alluded to above, you could also raise a patio with a retaining wall on the edge.
Now, if your home sits at the bottom of a hill, it is smart to protect against the real risk of flooding. Even if you live next to a decent-sized hill, a retaining wall (along with other drainage solutions and structures) can help to protect your home from harmful flooding and the risk of erosion. Without the wall, erosion of the hill’s soil can cause quite a bit of damage to your property over time.
Perhaps you have a walk-out basement or want to build a pool. Homes with the former require retaining walls to protect the entrance to the walkout basement. The same applies to a garage entrance that may be under the house. If you plan to install a pool, you’ll need to ensure that the land you build it on is perfectly level. In many cases, it’s tough to find a large-enough and flat-enough space to accommodate an in-ground pool without needing to level the soil. A retaining wall ensures that your land is perfectly level and suitable for a pool.
How a Retaining Wall is Built
In order to create a flat surface out of a hill, a contractor needs to install a compacted base material under the wall to provide a level surface to build upon. This is the the red material shown in the figure below, which sits under the first row of wall block.
Next comes the building of the retaining wall itself. In order to construct a retaining wall that will last decades, at least 10% of the height of the wall should be buried beneath ground. As shown in the figure, the first block sits beneath the surface.
In order to prevent erosion and protect the wall, drainage stone should be installed at least three-feet behind the wall. This is shown in the square-like section behind to the right of the retaining wall and below the plateau. It’s important that the excavated slope is as stable as possible, which ensures the longevity of the build. The backfill must be compacted with the proper wall materials to keep your property safe and looking beautiful for decades to come.
The Different Types of Retaining Walls and Materials Used
The two common types of retaining walls are gravity and engineered walls. Gravity walls work by using the weight of a block or stone material to hold the wall together and retain the soil. Engineered walls stabilize soil with Geogrid – a geosynthetic material that’s designed to reinforce soils and hold back the slope of a hill. The outside of an engineered wall is typically finished with a veneer (usually concrete wall block made to do the job) to provide a beautiful face to the underlying construction..
From natural stone to concrete, several different materials can be used to create different looking and functioning retaining walls.
Segmental retaining wall blocks are processed with an interlocking system to hold a wall together and fortify its structure.- Natural stone is typically appropriate for smaller walls and give a natural look. These are some of the most gorgeous stones.
- Wood timbers and railroad ties also provide a natural aesthetic that’s best used to build smaller walls - keeping in mind that wood does not have the longevity of stone and will rot with time.
- Gabion– wire baskets with stone inside – are a great option for homes in areas that get a lot of rainfall. This materials drains water very efficiently.
- Lastly, poured-in-place concrete is best for walls that must withstand the worst of flooding. Functioning like your home’s foundation, concrete walls are bested by no other material. They do require a footing below front however, so are not always the best solution. Building your wall from concrete won’t mean it will look like a concrete slab, though. These walls can be veneered with many different manufactured and natural products.
Before You Finalize Your Construction...
From protecting your property to adding more livable space, a retaining wall is incredibly valuable to many buildings. But don’t make the mistake of moving forward without first doing some homework.
First and foremost, do some research on your area’s permit process. Building a wall might require you to submit paperwork for approval or a permit. There may also be underground utilities below your home that your municipality has records of.
Similarly, you need to learn your area’s engineering requirements. For example, the state of Connecticut requires you to produce a stamped drawing from a licensed engineer before building anything over 36 inches. Other requirements will depend on the town where you live.
Beyond approvals, you also need to have a thorough understanding of what it will take to install a retaining wall. Additional necessities such as guardrails may affect your budget. In Connecticut, building code requires any structure over 48 inches tall to have a railing.
If you do your due diligence and work with a partner that can recommend the ideal way to build your retaining wall, you’ll have a structure that protects your property for decades while affording you more space and adding a beautiful touch to your home.
If this process seems a little daunting, you can always reach out to our experts for advice or have us give you an estimate to do the work for you. If you’re looking for a contractor to help, look over our contractor comparison checklist.
