Ballpark Estimate: $20 to $40 per square foot installed
When you need a retaining wall to keep your soil from eroding in your yard, it may be time to hire a structural engineer. This will ensure the final results will be sure to meet your specific goals.
Retaining Wall Basics
A retaining wall can come in different materials and structures, but regardless of its configuration, its overall purpose should be to provide support at any elevation in order to get the most out of your usable space and to prevent the soil from moving or washing away.
While the earliest retaining walls were used in ancient Rome to create roadways; today these support structures are commonly used by homeowners to make the most of their yard’s natural landscape. The basic retaining wall is designed to counter the pressure of the soil (or of a body of water in some cases) most effectively. Commonly, the retaining wall also needs to accommodate different weather conditions by having some sort of drainage system in place.
Not all retaining walls are created equal. A variety of styles and materials exist to handle different types of challenges. For instance, the retaining wall might be made from stone, brick, steel, vinyl or wood. The retaining wall design also can take on different structures, depending on the extent of the pressure it will need to endure.
Here is an overview of some of the popular retaining wall options that exist, along with a brief description of each.
Gravity Retaining Wall
A gravity retaining wall is a stacked wall that is typically made from stone or masonry blocks. Its design will be thicker at the bottom and will narrow out toward the top, creating a backward slant that will be able to resist the pressure of the soil and hold it in place. This retaining wall works best only up to heights of about four feet or less, although it can be adapted for larger spaces.
Cantilever Retaining Wall
A cantilever retaining wall is a wall that’s supported by a frame in the shape of an upside down “T.” The top of the “T” is installed into the ground, creating a strong base that can exert enough pressure on the soil to prevent it from sliding. A cantilever retaining wall usually is reinforced with steel to give it more strength. In addition, it can be buttressed with side walls or “wings” for added security.
Sheet Piling Retaining Wall
When your space is very tight, you may need a sheet piling retaining wall, which consists of vertical planks planted well into the ground to form a secure divider. Often a tie back anchor is placed behind the wall and is attached via a rod or cable for added strength.
Counterfort Retaining Wall
A counterfort retaining wall is similar in design to a cantilever wall, except that it relies on a triangular-shaped structure (instead of a “T”) coming off the back of the retaining wall to exert continuous pressure.
Concrete Retaining Wall
A tall concrete retaining wall provides a good foundation for your garden or other landscaping element. This is usually built with a very wide base that can help it stay strong and prevent it from being damaged by severe weather conditions.
Cinder Block Retaining Wall
Some people opt for a cinder block retaining wall in their gardens. The foundation is usually built right in a deep trench and secured by cement to ensure its effectiveness. Steel bars laid in an “L” shape are used to provide added support. A façade of bricks or stones can be added to the face of the retaining wall blocks to make it work with the overall look of your yard.
Block Retaining Wall
A block retaining wall made from interlocking blocks can be another appropriate choice for a garden. This design relies on gravity to keep the soil from sliding in much the same way as a gravity retaining wall.
Rock Retaining Wall
If you want your retaining wall to level out your flowerbeds or add an effective accent to your yard, a rock retaining wall is worth considering. This is built by stacking rocks and stones to create an attractive wall structure. Soil and plants are then used to fill in the gaps between the stones in the wall. As the plants grow, the roots can help to secure the soil in the wall, helping the structure become even stronger.
Where to Find a Contractor
You’ll need to select the best type of these or other types of retaining wall styles for your unique landscape. That’s where a structural engineer can bring important expertise to determine the most appropriate fit to meet the conditions that exist.
To find a qualified structural engineer, you can ask some local landscapers for recommendations. You can also look in your yellow pages or do a search online for contractors in your area. Some home improvement websites also provide a directory that you can use to search for local vendors. Some sites to try include FindanEngineer.com, Home Blue Contractor Network, Contractor Nexus, and theConstructor.org.
Cost for a Retaining Wall
Before you can determine the full cost of building a retaining wall, there are a number of factors that come into play. These include the size of the retaining wall to be built, the material used, the condition of the land (including the slant) and the retaining wall’s desired dimensions, including height, width and thickness. You’ll also need to consider how much work will be needed to clear the area in question in order to get it ready for the retaining wall installation process. With all of this in mind, here are some very general price ranges for materials and labor:
- A Wood Retaining Wall, commonly used railroad ties, redwood or pressure treated fir usually costs around $20 to $25 a square foot
- An Interlocking Concrete Block Retaining Wall will costs between $15 to $30 a square foot
- A Natural Stone Retaining Wall will cost between $25 to $50 a square foot
- A Poured Concrete Retaining Wall can cost around $30 to $40 a square foot
- A Retaining Wall with a Metal Foundation will cost you about $50 a square foot
So, you can expect to spend between $15 and $50 a square foot installed for a retaining wall project and up, depending on exactly what’s involved.
This means that if the retaining wall you are building will be 4 feet high by 12 feet long, it would cost anywhere between $720 and $2,400. In addition to the cost for the labor and material you select, the structural elements of your retaining wall can increase the price. For instance, if you are building a retaining wall that will be reinforced with steel frames, the materials and labor involved can end up being even higher than this.
There are also some other costs involved in building a retaining wall that you’ll want to consider. This includes clearing the lot, grading it and removing any brush and sod. Figure the cost for such prep work will be between $500 and $1,000 for a 1/4 acre. You’ll also need gravel, soil and drainage for the job. Make sure to find out if these costs are included in your price estimate, and if not, find out up front how much to budget for them.
Build Your Own
If you’re feeling particularly ambitious and decide to try building a retaining wall yourself, keep in mind that if the wall will need to be three feet or higher. The experts also recommend at least having a structural engineer provide the design plans for you to follow in order to ensure the final wall will accomplish your goals. Design plans for a retaining wall typically cost $500 or less.
In terms of the overall costs, you can expect a do-it-yourself retaining wall project to cost between 25 and 50 percent less than hiring a professional to provide the materials and the labor.