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How to Install Retaining Wall Footing Step-by-Step
As you begin planning the construction of a retaining wall, whether it’s to enhance your home’s curb appeal or prevent soil erosion in your backyard, it’s important to factor in one key aspect: the footing.
We’ll explain how to install retaining wall footing step-by-step and introduce you to the heavy-duty concrete pavers you can use for your retaining wall project.
Explore retaining wall pavers at Unilock
Does a Retaining Wall Need Footing?
Yes. A retaining wall requires footing to ensure a stable foundation for the wall.
Concrete footing for a retaining wall is a support structure designed to distribute the weight and pressure of a retaining wall evenly across the ground, preventing potential soil erosion, instability, and wall collapse or failure.
In addition to holding up a wall, retaining wall footing can help prevent water damage by redirecting water away from its base.
Types of Retaining Wall Footing
There are different types of retaining wall footings you can use depending on the soil conditions, the type of retaining wall, and the types of loads the wall will support.
- Spread footing: Spread footing, also known as shallow footing, spreads the weight of the wall over a wider area of soil. It is typically reinforced with steel bars or mesh to provide additional strength and durability. Spread footing is typically used for retaining walls that are 3 feet or lower and offer stable soil conditions made up of clay, sandy clay, silty clay and clay loam.
- Trench footing: Trench footing is distributed evenly along the length of the trench, making it suitable for areas with weak or unstable soil conditions. This type of footing is typically used for retaining walls that are 4 feet or higher.
- Strip footing: Strip footing is similar to spread footing, but it is typically used for longer retaining walls or walls that need to support heavier loads. It consists of a long strip of concrete that distributes the weight of the wall over a larger area.
- Pile footing: Pile footing is a type of retaining wall footing in which columns of reinforced concrete, steel or timber are drilled deep into the ground to transfer the load of the wall to more stable soil layers or rock formations below.
How to Calculate Retaining Wall Footing Depth and Width
The right depth for retaining wall footing depends on the height of the wall.
Refer to the table below to see how deep and wide your retaining wall footing should be:
Wall Height (H)
|Footing Width (W)||
Footing Depth (d)
|0 – 2 feet||12 inches||
|2 – 4 feet||18 inches||
|4 – 6 feet||24 inches||
Tools You’ll Need to Install Footing for a Retaining Wall
To install concrete footing for a retaining wall, you will need the following tools and materials:
- Measuring tape to measure the dimensions of the trench and footing.
- Stakes and string to mark the retaining wall location and create a straight, level line.
- Shovel or excavator to dig the trench.
- Level to ensure the trench bottom, formwork and poured concrete are level throughout the installation process.
- Hand tamper or plate compactor to compact the gravel or soil base.
- Screed board to level freshly poured concrete, ensuring a leveled surface. It is typically made of wood or aluminum.
- Gravel or crushed stone (optional) to stuff the backfill behind the wall.
- Formwork to form concrete footing. Formwork materials include timber, steel, fiberglass or plastic.
- Hammer and nails or screws to secure the formwork boards together.
- Reinforcement materials to provide extra strength and stability to your concrete. Reinforcement materials include a steel rebar or mesh.
- Concrete mix to help you create concrete.
- Wheelbarrow to transport materials such as crushed stone, gravel, or sand to the work area.
- Safety gear (P.P.E.) to protect your body when dealing with concrete. This may include gloves, safety glasses, hard hats and respirators.
How to Install Retaining Wall Footing in 10 Steps
Installing concrete footing for a retaining wall involves several steps to ensure proper support and stability.
Here’s the step-by-step process:
1. Secure a Building Permit
Before you start installing your retaining wall footing — or building your retaining wall in general — check with your local municipality to see if you need to secure a building permit.
Typically, you will only need a building permit if you plan on building a wall that is more than 4 feet tall.
2. Excavate the Trench
Dig a trench along the area where the retaining wall will be built. To determine the depth of the trench, keep in mind that you’ll need 2-3 inches for your gravel base. The depth should be enough to bury half of the first layer of blocks, plus the gravel base.
If your pavers are 4 inches, for example, the trench should be 5-7 inches deep.
When it comes to the width, you’ll want to double the width of your blocks.
3. Level and Compact the Base
Add a layer of sandy soil or gravel — at least 12 inches deep — to provide drainage and stabilize the footing for the wall.
Using a vibratory plate compactor or hand tamper, level the surface by going over the gravel or sandy soil layer.
Then, install a layer of geotextile fabric on top of the base to prevent soil from filtering through the sandy soil or gravel.
4. Install the Formwork
Set up the wooden or metal formwork to contain the concrete footing.
To create a formwork for concrete:
- Determine the dimensions, shape and layout of the concrete footing you want to create, and gather all necessary materials, such as plywood or timber boards, stakes, screws, nails and a level.
- Cut plywood or timber boards to the desired size according to your plan. Ensure that the boards are straight and free of defects to create smooth concrete surfaces.
- Build the formwork structure by connecting the boards with screws or nails to create the desired shape. Use stakes or braces to support the formwork from the outside to prevent it from collapsing under the weight of the wet concrete.
- Use a level to ensure that the formwork is level horizontally and vertically.
5. Add Reinforcement Materials
Once you’ve built your formwork, place steel bars or mesh within the formwork to reinforce the concrete and improve the footing’s load-bearing capacity.
6. Coat the Formwork With a Release Agent
Coat the inside surfaces of the formwork with a release agent to allow easy removal of the formwork from the poured concrete.
While release agents are available in your local home improvement store, consider using everyday materials, such as vegetable or mineral oil, as well.
7. Create the Concrete Mix
Next, if you already have ready-mix concrete bags, simply add water.
To create the concrete mix from scratch:
- Gather cement, sand, water and gravel to create the concrete mix. Prepare a wheelbarrow or mixing container, a shovel and a bucket for measuring.
- Identify the correct mix ratio of the concrete to ensure the concrete gets the ideal, peanut butter-like consistency. The right consistency also ensures the concrete is durable. The most common concrete mix ratio is 1:2:3. This mix is composed of 1 part cement, 2 parts sand and 3 parts gravel.
- Pour the cement, sand and gravel into the wheelbarrow to start creating your concrete mix. Then, gradually add water to the dry mix while stirring with a shovel. A good rule of thumb is to use about .75 gallons of water for every 80-pound bag of cement. Use a shovel to thoroughly mix the dry materials together until they are evenly distributed and have a uniform color.
- Perform a slump test to check the consistency of the concrete by filling a cone-shaped container with the concrete, compacting it and then removing the container. The concrete should slump slightly but maintain its shape overall.
8. Level the Concrete
Next, pour the fresh concrete into the formwork and start leveling the concrete surface.
To level concrete, use a screed board to even out the freshly poured concrete across the formwork. Move the screed back-and-forth while topping up low spots and removing any excess concrete as needed.
9. Allow Concrete to Cure
Then, allow the concrete to cure for at least one to 2 days.
During this time, ensure that the concrete stays moist by regularly spraying it with water or covering it with a damp cloth to prevent it from cracking.
10. Remove the Formwork
Once the concrete is fully cured, remove the formwork and proceed with building the rest of the retaining wall.
Check out our full guide on building a retaining wall for more info!
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Build Your Retaining Wall With Heavy-Duty Pavers From Unilock
For over 50 years, Unilock has been committed to crafting exceptional outdoor spaces across North America.
As an industry leader in the retaining wall and paving stones industry, we produce top-quality products, while delivering unparalleled customer service.
Our heavy-duty pavers serve as interlocking concrete wall blocks, designed to guarantee stability, security and outstanding visual appeal for your retaining wall.
Choose from an array of styles, including stacked blocks that mimic natural stone, or eye-catching wall pavers to transform your retaining wall into a stunning and functional structural piece.
Our Classic Coat technology provides a factory-sealed coating that enhances the color of our Classic thru-mix pavers and helps protect their surface from wear.
Explore our extensive collection of retaining wall pavers at Unilock to discover the product that captures your unique style, whether you’re looking for a design that embodies a contemporary flair, or one that radiates timeless warmth. We’ve got you covered.
Transform your retaining wall with Unilock. Explore heavy-duty wall pavers!
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