What Exactly is a deadman retaining wall anchor, or more generally, what is a deadman in construction in more general terms? What are the purpose and design of these anchors? These are the questions, let’s get to the answers.
A retaining wall deadman anchor is a buried structure used to stabilize a retaining wall. The deadman anchor consists of a large, heavy object that is buried in the ground next to the retaining wall. The weight of the backfill dirt covering the object anchors the retaining wall in place and prevents it from sliding downhill or leaning outward from the top.
A retaining wall can be designed to hold back earth, water, or other materials. When you build one it will need anchors that provide additional stability for the structure. These anchors come in many different shapes and sizes but they all have one thing in common: they provide a way to tie down the retaining wall.
If you’re interested in learning more about building a railway tie retaining wall and covering it, or perhaps you’re curious about how to install landscape timbers on a slope? If so, you’re in luck! We have two other articles that delve into these topics in detail. In “How To Build A Railway Tie Retaining Wall And Cover It,” with an overview on constructing a sturdy and aesthetically pleasing retaining wall using railway ties. And in “How To Install Landscape Timbers On A Slope,” we explore the best practices for creating a landscape structure on a slope.
What Can A Deadman Anchor Be Made Of?
When considering deadman anchors, you may be wondering about the materials that can be used. The options are surprisingly diverse, allowing for flexibility in construction. A deadman anchor can be fashioned from a variety of materials, ranging from a sizable rock or a carefully arranged pile of rocks to a sturdy piece of metal.
These anchors are buried strategically, ensuring that the top is flush with the soil surface, providing a solid foundation for the retaining wall to rest upon. By exploring different materials for your deadman anchor, you can choose the option that best suits your needs and complements the overall design of your project.
Deadman: Most Popular Kind Of Retaining Wall Anchor
The most popular type of anchor is called a deadman wall anchor and there are two different kinds that can be used for this purpose. First, you will need vertical poles that have been placed into holes drilled in the earth and then filled with concrete or steel rods if you are going through bedrock. Then you will need horizontal poles that have a loop at the end to attach cables or chains and then both ends of these loops will be hooked onto something heavy like boulders, car tires or steel plates. Check out the following video.
💡 When setting posts for a retaining wall, it is important to have at least two inches of concrete on all sides of the post. Having more concrete is better for structural integrity.
💡 Most rot in retaining walls occurs at the line where the concrete base meets the soil. To minimize rot, it is recommended to build up the concrete base and create round bases to prevent water accumulation.
💡 The dead man design consists of a triangle shape. It helps transfer the load of the soil on top of the footing to prevent the wall from lifting and leaning.
💡 Exposed wood in pressure-treated wood is vulnerable to rot. Treating the raw edges and exposed parts with pressure treatment or paint is important for longevity.
💡 The video mentions the use of pressure-treated wood from a local company that sells FSC-certified lumber, indicating sustainable harvesting practices. Sustainability considerations include the longevity of the structure and the toxicity of the treatment used.
💡 In the East Coast, there is a type of pressure-treated wood called “timber cell” that is treated with silicon instead of chemicals. It is said to last up to a hundred years and can be turned into compost when replaced.
The second type is called an anchor bolt which can also be used for vertical walls that either go straight up from the ground or are angled outwards. These anchors will be screwed into the earth, ideally with a set of bolts on each side to hold them in place better and then they can either have their own loop for attaching cables or chains (or sometimes just one) if it’s going through bedrock.
The first type is more popular because you don’t have to worry about driving the anchor rods all the way into bedrock, but they are more expensive and harder to install.
This type of wall is not only great for stabilizing a hillside or preventing erosion on an embankment, but it also provides opportunities for beautiful landscaping with shrubs, flowers, vines and trees.
Tips On Making A Deadman Anchor
Deadman anchors are essential for reinforcing the stability of retaining walls, and creating one is easier than you might think. One popular method involves using two pieces of durable landscaping timber, forming a cross shape. Begin by securely nailing the first piece to the retaining wall timbers, ensuring it extends deep into the ground for maximum support.
Next, affix the second piece to the first one with sturdy nails, making sure it extends downwards by at least the same length as the first piece. To provide adequate leverage, the second piece should extend at least 1 foot beyond the top of the retaining wall. By following these straightforward steps, you can create a robust deadman anchor, reinforcing the strength and durability of your retaining wall.
💡 Carriage bolts should be avoided when constructing the retaining wall as they can be difficult to remove and replace. Hex head bolts with washers should be used instead.
💡 Galvanized wood or galvanized hardware should always be used to ensure longevity and durability of the retaining wall.
💡 Pressure-treated wood is the most suitable option for ground contact, although redwood can also be used but won’t last as long.
💡 The base where the horizontal and vertical four by fours meet is not load-bearing, and all the load is transferred through the diagonal.
💡 The ends of pressure-treated wood should be protected from the elements using copper treatment, paint, or tar to prevent wood decay.
💡 A 2 by 12 is placed on top of the base four by four to prevent the retaining wall from moving when soil is added on top.
💡 The first run of the retaining wall is placed in the ground, and concrete is built up around it to shed water off the post.
💡 Bolts are crucial for holding the retaining wall in place. There are bolts on the top and bottom of the Deadman, as well as diagonal bolts.
💡 The combination of bolts on the diagonals, horizontal rails, and the plank supporting the bottom four by four provides the core strength of the retaining wall.
💡 The retaining wall should be constructed properly to ensure longevity of 30-50 years.
What is a Deadman Brace Retaining Wall Or A Deadman Anchor Retaining Wall?
- A type of retaining wall used to hold back soil on a slope or hillside[1][2]
- Uses “deadmen” as anchors tied into the retaining wall to provide stability[1][2]
How a Deadman Brace Works
- Deadmen are heavy wooden beams or timbers buried perpendicular to the wall[2][3][4]
- They act as anchors, resisting the pressure of the soil pushing on the wall[2][4]
- Cables or rods connect the deadmen to the retaining wall[2][4]
- Having deadmen installed every 6-8 feet helps brace the entire wall[5][6]
Building a Deadman Retaining Wall
- Dig trenches for deadmen and retaining wall footing[3][6]
- Install perforated drainage pipes behind wall[6]
- Position deadmen in trenches and backfill with compacted soil[3][4]
- Attach wall boards to deadmen with cable/rods[4][6]
- Backfill behind wall and compact soil in layers[3][6]
- Add additional courses of wall boards as needed[6]
So in summary, deadman brace retaining walls use perpendicular deadmen anchors to provide added strength and stabilization to the wall. The deadmen brace against soil pressure.
Citations:
[1] https://orlandi.com.au/what-is-a-retaining-wall-deadman/
[2] https://diyretainingwall.com/how-to-build-a-timber-wall-with-deadman-anchors/
[3] https://youtube.com/watch?v=7Db9_wT9kiU
[4] https://www.motherearthnews.com/diy/build-a-retaining-wall-zmaz86jfzglo/
[5] https://www.diychatroom.com/threads/deadman-yes-no.332849/
[6] https://www.thisoldhouse.com/landscaping/21018759/how-to-build-a-timber-retaining-wall
FAQ
Q: What is a retaining wall deadman anchor?
A: A retaining wall deadman anchor is a construction technique used to stabilize retaining walls by providing additional support.
Q: How does a retaining wall deadman anchor work?
A: A deadman anchor consists of a long timber or metal rod that is buried in the ground behind the retaining wall. The rod extends from the bottom of the wall and is attached to an anchor or brace that is embedded in the ground. This helps to distribute the weight of the wall and prevent it from tipping over.
Q: Why is a deadman anchor important in retaining wall construction?
A: A deadman anchor is important because it helps to prevent the retaining wall from shifting or collapsing under the pressure of the soil behind it. It provides additional stability and ensures the longevity of the wall.
Q: Can I install a deadman anchor myself?
A: Yes, it is possible to install a deadman anchor yourself. However, it is important to follow proper construction techniques and guidelines to ensure the anchor is installed correctly and provides the necessary support.
Q: What materials can be used for a deadman anchor?
A: Deadman anchors can be made from timber or metal rods, depending on the preference and requirements of the retaining wall. Timber is commonly used for smaller walls, while metal is preferred for taller and heavier walls.
Q: How deep should a deadman anchor be buried?
A: The depth of the deadman anchor will depend on various factors such as the height of the retaining wall, the type of soil, and the local building codes. As a general guideline, the anchor should be buried at least one-third of the height of the wall.
Q: Do I need to use a wood preservative on the deadman anchor?
A: It is recommended to use a wood preservative on timber deadman anchors to protect them from rotting. This will help extend the lifespan of the anchor and ensure its effectiveness in supporting the retaining wall.
Q: What tools are required to install a deadman anchor?
A: The tools required to install a deadman anchor include a shovel, a circular saw for cutting timber, a level, and a tape measure. Additionally, you may need a drill or a hammer for attaching the anchor to the retaining wall.
Q: Can I use any type of soil for backfilling the deadman anchor?
A: It is important to use suitable soil for backfilling the deadman anchor. The soil should be compacted and well-draining to prevent water build-up and soil erosion. Additionally, using a filter fabric between the soil and the anchor can help improve its stability.
Q: Are there any height limitations for using deadman anchors?
A: Deadman anchors can be used for retaining walls of various heights. However, for taller walls that exceed 4 feet, it is advisable to consult with a professional engineer or contractor to ensure proper design and installation.
Q: Is a dead man tie back the same as a deadman anchor?
A: Yes, a dead man tie back and a deadman anchor serve the same purpose and are different terms for the same thing.
Conclusion
To conclude, understanding the importance of retaining wall deadman anchors is crucial for anyone considering building or stabilizing a retaining wall. These buried structures play a vital role in preventing the wall from sliding downhill or leaning outward, providing much-needed stability. If you’re interested in delving deeper into related topics, we encourage you to explore our articles on building a railway tie retaining wall and covering it, as well as installing landscape timbers on a slope. These comprehensive guides will provide you with step-by-step instructions and best practices for successful construction and landscaping projects. Remember to consider the materials and types of anchors you use, such as deadman wall anchors or anchor bolts, to ensure long-lasting stability. Whether you’re tackling a hillside stabilization project or creating an aesthetically pleasing landscape, incorporating these anchoring techniques is essential.
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