The cost of building a concrete retaining wall can vary greatly depending on the types of materials you choose and your access to labor. However, this article will give you an idea of what you can expect to pay for a typical job.
The first step in determining how much it costs to build a retaining wall is measuring the length and width of your project. For example, if your project is 10 feet by 15 feet (150 square feet), then you can multiply those numbers together to get 1,750 square feet of wall surface area: 150 x 150 = 1,750.
Next, divide that number by 100 square feet per cubic yard (3 feet x 3 feet x 3 feet) to determine how much material you need: 1,750 / 100 = 17.5 cubic yards.
Let’s say that you prefer using concrete blocks instead of poured concrete slabs because they’re less expensive and easier to install on your own (though not necessarily). The average price of concrete blocks is approximately $2 per block and each standard block weighs approximately 20 pounds, so 17.5 cubic yards equals ~836 tons of concrete blocks: 836 / 20 = 42
Cost to build concrete retaining wall
A retaining wall holds back an embankment of soil from an adjacent lower area. Retaining walls control erosion and create flat areas for use. Masonry, wood and stone are the most popular retaining walls because of their cost-effectiveness, availability and ease of installation.
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On average, building a retaining wall costs $23 per square foot. For the more budget-conscious, retaining wall prices average at $19 per square foot. On the upper end, retaining wall costs are around $50 per square foot.
Average Retaining Wall Cost
MATERIALS COST PER SQUARE FOOT
* Costs per square foot
Retaining Wall Cost Per Square Foot
As with other building materials such as pavers or roofing, square footage is a convenient way to compare the cost of different types of retaining wall materials. The length of the retaining wall multiplied by its height helps you calculate its total square footage.
The height of the retaining wall is a major factor in determining the total cost of the retaining wall. Higher retaining walls become exponentially more costly, especially after they surpass permit and inspection limits.
For example, a retaining wall that is 50 feet long and two feet high is vastly different from another retaining wall that is 20 feet long but five feet high. Though both walls are 100 square feet, the first wall is so low that nearly any type of material can be used, even ordinary pressure-treated lumber. The second wall requires more robust materials such as large retaining wall blocks and may even require design plans reviewed by a structural engineer.
Retaining Wall Cost by Material Type
The type of materials used for the retaining wall is a two-tier factor in the overall cost of the retaining wall.
First, there is the cost of the materials alone. This cost is dependent on location, season, market variations and local building conventions. Natural stone is commonly found in the Pacific Northwest, the Northwest and the Northeast of the United States, so it is less expensive in those areas.
Second, the type of materials determines other factors such as the method of building, the need for deeper footers, labor force and more. Stone rockeries require cranes, which may entail crane rental and even costs to control traffic. Railroad ties, often permeated with toxic creosote, may require special permitting in some areas or may not even be allowed.
In some areas of the Midwest and Southwest, natural stone is not as common, so it must be shipped long distances. Not only that but there are fewer contractors and laborers who are familiar with the product in those areas.
Block Retaining Walls
Retaining block walls will cost $16 per square foot for the average professional installation. That’s $1,600 for a 100 square foot retaining wall—basic, with no extras and under four feet.
On the upper end of the scale, for larger 16-inch decorative blocks and for extras like cap pavers and wall curves, expect to pay up to $30 per square foot. Averaged out, retaining wall blocks cost about $23 per square foot.
Wood Retaining Walls
For wood retaining walls, you can expect to pay between $16 and $28 per square foot for a professionally installed wall. Taking on the job by yourself can bring the cost down to as low as $10 per square foot. On the whole, wood retaining walls cost about $19 per square foot.
Natural Stone Retaining Walls
Depending on the type of stone used and the distance from the property to the supplier or quarry, natural stone retaining walls can cost from $25 to $75 per square foot. On the average, natural stone retaining walls cost about $50 per square foot.
TYPE OF RETAINING WALL MATERIAL
COST PER SQUARE FOOT
Retaining wall block
$16 – $30
$10 – $28
$25 – $75
Retaining Wall Block Costs
Retaining wall block has become one of the most popular types of materials to build retaining walls. With its front lip and tipped back profile, it is one of the few materials designed expressly for retaining walls.
Retaining wall block will not degrade, nor does it require much in the way of maintenance other than occasional cleaning. Also, the masonry materials in retaining wall block are inexpensive to source and to produce. The greatest cost of retaining wall block is shipping since it is so heavy.
Larger size decorative retaining wall blocks are more expensive than smaller blocks. Large blocks are capable of holding back more soil and can be built higher. Not only that, their faces can be textured for decorative purposes.
The cost of the retaining wall block forms the majority of the total cost of the retaining wall. Decorative 17-inch block costs about $570 per pallet, which covers nearly 35 square feet of wall face: about $12 per block.
On the lower end of pricing, plain gray concrete retaining wall block, also 17 inches, can cost about four times less than decorative block: as little as $3.40 per block.
Retaining Wall Labor Cost
Along with the cost of materials, the second half of the pricing equation—and sometimes the most important half—is the cost of labor to build the retaining wall.
Generally, contractors will provide you with a quote that includes labor. Labor to build a retaining wall costs from $50 to $75 per hour. If the project requires consultation with a structural engineer, hourly charges range from $100 to $200 per hour.
Labor costs for building retaining walls vary according to the type of wall, season and the current demand for labor.
Masonry retaining block and wood retaining walls can employ some unskilled and semi-skilled workers for hauling gravel, digging out footers and carrying blocks. Wood retaining wall projects, too, are often driven by skilled workers who can oversee less skilled, inexpensive laborers.
Setting rockery walls that are safe and aesthetically pleasing is an art form as much as it is a trade, and this is best left in the hands of skilled, higher-paid workers.
When to Install a Retaining Wall
Install a retaining wall when a slope is encroaching on your property and you need to carve out space for a patio, pool, addition or any other area that requires flat level ground.
Soil slopes that exceed 35 degrees can become unstable and dangerous and need to be retained. This depends on the type of soil that you have.
Retaining walls can be built at nearly any time of the year, in nearly any climatic condition. If the ground is frozen, it can be difficult to dig to reach below the frost line.
The type of retaining wall that you choose depends as much on your needs as on your budget. If you need to replace a retaining wall that is in danger of falling down or if you have a slope dangerously encroaching on your property, building a functional, safe retaining wall of any type is critical.
But if you are undertaking an elective home improvement project, you may want to make a decision based on the appearance of the wall and on your budget. Walls that are low enough can even be built by do-it-yourselfers.