How Much do Block Retaining Walls Cost?
$16 Per Square Foot, Installed
Block Retaining Walls and Installation Costs
$950 – $2,200
Average Cost Estimate
$1,400 – $2,900
$2,100 – $3,800
|Estimated Length||100 sf Wall||100 sf Wall||100 sf Wall|
|Block Type||Basic 11 – 14″ Blocks||Basic 11 – 14″ Blocks||Attractive 16″ Blocks|
|Cost Per / Vertical Sqft||$6-$8 / sqft||$8 – $15 / sqft||$12 – $30 / sqft|
|Installed By||DIY with Helper||DIY w/Helper Or Pro||Pro Installation|
|Finish||Cast Concrete||Cast Concrete||Pebble Face or Natural|
|Features||None||Cap / Seats / Curved Wall||Cap / Seats / Curves|
|Block Costs||$400 – $450||$0 – $450||Included|
|Supplies||$200 – $350||$0 – 350||Included|
|Install Difficulty (Yard)||Simple Wall on Simple Slope||Moderate Wall on Simple Slope||Advanced Wall / High Slope|
|Permit, Survey, Engineer||$75 – $325||$75 – $325||$75 – $325|
Overview of Landscaping Block Retaining Walls
A block retaining wall provides visual appeal to the landscape while giving stability to the earth it is holding, whether a sloped or excavated area or garden bed. Made from precast concrete blocks that often have a locking flange or lip for stability, block retaining walls last indefinitely when properly installed. As opposed to a wood retaining wall, concrete blocks last longer and look better for many years with very little maintenance.
This Costimate gives you detailed block retaining wall cost estimates for materials, supplies and the labor required to install one if you don’t do it yourself. Our goal is to assist you in planning the block retaining wall cost and the time required to build your retaining wall to prevent erosion, or a block landscape wall to showcase your yard.
Product and Supplies Cost Details
Block Retaining Wall Cost Factors
The costs in this section covers block retaining walls up to three feet high. Beyond that height, special materials and techniques are required to give high retaining walls necessary strength and stability. With that parameter in mind, here’s what you’ll need to consider in preparing a budget for your block retaining wall.
- Square Feet of Wall Face: Divide the height of the wall by the height of the blocks to determine the number of rows/courses needed. For example, a 24” tall wall built with 6” blocks will have 4 rows. If the wall will be 60’ (720″) long and the blocks are 8” long, then you’ll need 90 blocks per row, for a grand total of 360 blocks. Add 5% more, or 18 blocks in our example, to cover damaged blocks, edges that need to be fit into place, and a few extra blocks for repairs in the future.
- Block Style – There are several types of blocks commonly used in block retaining walls. The most common (and cheapest) are the plain, interlocking blocks found in home improvement stores like Lowes and Home Depot. Above these, you can get scalloped face blocks and several other styles that have different face finishes, as well color and styles. Keep in mind, the more attractive the block, the higher the blocks will cost.
- Base Gravel Material: A trench 8” deep and twice the front-to-back width of your block will be dug and filled with paver base or gravel.
- Perforated Drain Pipe: Installing drain tile at the inside base of the wall will be necessary to remove water that would soften the ground and destabilize the wall.
- Mixed Drainage Stone: In most cases, you’ll use pea-gravel underneath your drain pipe, and a 3/4 drainage stone 6-18 inches on top of the pipe, depending on depth and drainage needed.
- Tools: DIY installers may need to acquire some of the tools in the assortment used for the work. We price the more expensive tools below.
Cost of Supplies
Here are specific prices that will allow you to put a block retaining wall cost estimate together as if you were planning DIY installation.
- $4-$12 | Stakes and string or marking paint to mark the path of the wall.
- $40-$65 | 6’ level for assuring that the wall bed is level and the wall is straight.
- $0.50-$11.00 ea. | Precast concrete (also called modular or interlocking) blocks as small as 3.5” x 7” on face and as large as 6” x 18” on face, with the majority costing $2-$8 each.
- $3.50-$5.00 | If needed – Precast concrete capstone is required for installation on top of block with an open interior similar to cinder block structure.
- $3.00-$4.50 ea. | .5 cubic foot bags of retaining wall base; About two bags per every three linear feet of wall are needed.
- $20-$24 per cubic yard | Gravel can be used beneath the first row of block in place of wall base, and a 4” layer of it is installed at the inside base of the wall to facilitate drainage
- $55-$75 ea. | 50’ roll of quality 4” perforated drain tile to lay along the inside base of the wall on top of the gravel
- $40-$50 ea. | 100’ roll of professional-quality landscape/filter fabric to lay over the drain tile to keep sediment out of it, with more gravel on top to hold the fabric in place.
- $40-$150 ea. | Circular saw used with a masonry saw blade to cut blocks when staggering rows
- $15-$50 ea. | Masonry saw blade
- $25-$40 ea. | Hand tamper for tamping the base or gravel beneath the wall and at the inside base of the wall
These are retail costs. Landscape contractors typically have wholesale accounts with material suppliers, so might offer better pricing on similar materials to what you find retail.
Permits, Inspection, and Installation Costs
There are a few miscellaneous expenses you might encounter that become “hidden costs” if you don’t know about them.
Permits and Inspection
Your local building department will let you know if a permit is required. Most communities don’t require a permit to build walls this size.
- $35-$150 | Cost of a permit and inspection, if required
- $0-$75 | Locating and marking underground utility lines to avoid building your wall on top of them is often done free after a call to 811. If you must pay for the service, the cost should be $75 or less.
Note on Homeowner Associations: If you’re part of an HOA, check the bylaws for rules about block walls. Violating the bylaws and having to modify, move or remove a block wall is a major unexpected cost.
Installation Cost and Time
Building a block retaining wall or garden wall is one of those home improvement projects in which the cost of labor is equal to or greater than the cost of the materials. As you get block wall estimates, expect the labor to be itemized at:
- $4-$10 per square foot of wall face | Block wall installation
Now, here are the factors that will determine where on that cost spectrum your project falls:
Location of your Home – When the landscape crew must travel further and use more fuel to get to your home, cost estimates will rise.
Length of the Wall – Given two walls with an equal number of square feet of wall face, the longer wall will cost more to install due to the need to trench the base, add base material and construct drainage.
Stepped Walls – If the wall is stepped to accommodate slope, it will take longer to build and cost more.
Removal of Obstructions—Removing old walls, trees, roots, shrubs or other obstacles will raise the price according to the time added to the work.
Time of the Year – When landscape companies are very busy, their rates are less competitive. In regions with cold winters, having the wall built as soon as conditions are suitable in the spring or just before the season ends in the fall might yield more competitive block retention wall prices.
Smart homeowners understand that getting bids from landscape companies that know they’re competing for the work ensures the best block retaining wall price.
Completed Installation Time
How long does it take to install a block retaining wall? Here’s an estimate based on a wide range of projects.
- 1-2 days | Simple installation of small walls
- 2-3 days | Simple installation of medium-sized walls or complex installation of small walls when the path is stepped and/or curved
- 3+ days | Installation of longer and/or more complex walls
Here’s what a typical schedule will look like for a crew of two people:
Day 1 – Digging the trench for the base row, pouring base material or gravel and tamping it down, installing the drainage system, beginning the wall
Days 2-3 – Completion of small to medium walls
Day 4 and beyond – Completion of larger walls
DIY or Hire a Pro
I’ve installed small, block retaining walls, as well as small border type retaining walls out of landscaping timbers. I’ve never put in a structural or timber retaining wall. That said, you’re going to need a lot of skill and a good bit of help to get the job if you choose to do it yourself.
- Requires a lot of digging and planning.
- Good with a wide array of hand tools, math, power tools.
- Able to lift heavy materials.
- Your going to need a few helpers and a good wheelbarrow driver.
If you’re a moderately experienced DIY’er, I don’t think you’ll have much trouble installing your own timber retaining wall. However, I still think it’s something left to the Pros.