How to Build a Wood Retaining Wall

Is your backyard sloping and hard to walk on, much less set up some cozy chairs for a barbecue session? Do you want to have more level areas to finally be able to plant that flower garden you have always dreamed of? A retaining wall might be the answer. 
 
Retaining walls are permanent fixtures designed to hold back the soil and create level areas of land above and below the retaining wall. It serves many different purposes, both in function and appeal, from preventing erosion, to redesigning the surrounding landscape, and more. ​

These can be made in a variety of ways, such as gravity type and pillar type walls being the most common, with more complex designs being cantilevered and anchored type walls, which are more often used on large scale construction and landscaping such as roadways. 
 
Deciding on the type of  on the layout of the property and other factors concerning the land, such as: 
 

• Soil type 
  
• Amount of runoff 
  
• Level of sloping 
  
• Climate 
  
• Proneness to natural calamity 
  

• Weight above the wall 
  
• Neighboring structures 
  
• Local building codes 
  

 
A retaining wall can also be made with many different materials. Choosing the right one means taking into account not just your personal taste and preference, but also the layout and properties of your land. Here are the most commonly used building materials for retaining walls: 
 

• Wood 
  
• Concrete 
  
• Stone 
  
• Brick 
  

 
Wood and stone are the most affordable building materials for retaining walls, and are both easy to use when doing the project yourself. These give off a natural look that blends well with most surroundings.  
 
If you are aiming for a natural but structured look, or wanting to build a wall that doubles as a fence, then wood is the best option for you. 
 
If you want to find out how to build a wood retaining wall, here's how: ​

Step 1: Research

Before doing any construction project, whether you hire a professional contractor or go with the do it yourself approach, you must first do a proper research to make sure that your project will be safe and successful. 
 

1. Understand the layout of your land and identify all the factors that would affect the retaining wall you are going to build. 
   

 
A wood retaining wall only works if: 

• The intended land above the wall is bare of heavy weight objects such as houses, sheds, pools, and even large trees 
  

• The slope of the land above and below the intended wall is at a ratio of 2:1 or less 
  
• There is not too much water runoff from the soil 
  
• The area is not subject to harsh weather patterns 
  

 

1. Research on local building codes in your area, as well as requirements for acquiring permits. 
   

 
Typically, a homeowner is allowed to self-construct a retaining wall within these parameters: 

• The wall is at maximum 2 ½ to 3 feet height 
  
• The slope of the land does not exceed 2:1 or 3:1 
  

 

1. Call the 811 "Call Before You Dig" hotline to ensure that you will not be accidentally damaging utility lines that lie underneath your property. 
   

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Step 2: Gather materials

Make sure that you have all the materials and equipment you will need before starting on the project. For building a wood retaining wall, here is a list of materials and equipment to prepare: 
 

• 4x4 posts 
  
• 2x6 boards 
  
• Cement mixture 
  
• Gravel 
  

• Carriage bolts 
  

 

• Rake 
  
• Stakes and strings 
  
• Shovel 
  

• Hand float 
  
• Level 
  
• Drill 
  
• Wood saw 
  

 
The amount of wood posts and boards you will need depends on the size of the wall you want to build. For the 4x4 posts, the minimum length should be 
 
Desired height of the wall + 18 inches 
 
While the boards should be 3 feet in length. To calculate how much you need, follow this guide: 
 
Desired wall length ÷ 3 = # of 4x4 posts 
(Desired wall height ÷ 6 inches) x # of 4x4 posts = # of 2x6 boards 
 
Make sure to only buy pressure treated lumber that are made especially for retaining walls. ​

Step 3: Prepare the area

Once you have all the materials ready, you can proceed with preparing the area for the retaining wall. 
 

1. Identify which part or parts of your property would benefit most from a retaining wall (and is safe for you to build one yourself). 
   

 

1. Measure the area where you want to build a retaining wall on, in order to calculate the length of the wall. If the retaining wall is going to be on more than one side, take note of this and prepare the appropriate amount of building materials. 
   

 

1. Clear the working area from all kinds of debris- rocks and pebbles, plants, roots, and weeds, as well as litter. Make sure to fully uproot plants and weeds to prevent them from growing into the wall. Otherwise, it can be the cause of wall failure. 
   

 

1. Rake the soil until it is flat and level. 
   

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Step 4: Mark the land

After the land has been prepared, it is now time to mark where you want the wall to be. To do this, start by placing a stake on one end of the wall. Then, measure 3 feet from there and add another stake. Keep doing this until you reach the other end. 
 
Note that if a certain area of the land above the wall is heavier than others, such as if there are plants or a walking path, make the distance between your posts shorter, about 16 to 18 inches, for these areas. 
 
Then, mark the height of the wall by attaching a string on the stakes. 
 
If your posts and boards are not yet cut to size, this is the perfect time to do it. ​

Step 5: Dig a trench

The next step is to dig a trench, which will serve as the placement for the base of your retaining wall. Take note of these measurements when digging the trench: 
 

• For the spots where the posts will be, dig 18 inches deep 
  
• For spaces between the posts, dig 12 inches deep 
  

 
Once you have already dug the trench, clear it from debris and kill all roots and weeds. This is the foundation of your retaining wall and therefore has to be clear of anything that might make it weaker. 
 
Then, level the trench using a flat object and a bubble level.  
 ​

Step 6: Insert the posts

Now it is time to insert the posts. Follow these steps on how to do it properly: 
 

1. Fill the trench with concrete using an appropriate mix of cement, gravel, and water. This will be the foundation of the wall. 
   

 

1. Level the concrete using a hand float. Make sure that the surface is flat and even. 
   

 

1. Insert the posts. It is important to make sure that these reach the bottom of the trench, and are standing upright at a perfect 90 degree angle from the ground. 
   

 

1. Let the concrete cure for one week. 
   

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Step 7: Add the boards

The final step is to add the boards so that your retaining wall can come together nicely. Here is how to do it: 
 

1. Attach the boards using a drill and carriage bolts. Make sure that the ends of the boards meet in the middle of the posts. 
   

 

1. Space the boards evenly by using penny nails or drill screws in between each board. 
   

 

1. Finally, add a backfill to the wall using the soil you removed. Make sure that this reaches the top of the wall  
   

 
You can also paint or stain the wood to match the rest of your house. ​

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​Contact our specialists here at Retaining Wall Irving at (469) 804-3311 and get a FREE ESTIMATE!