Retaining Wall Installation in 10 Steps

Retaining walls make slopes more usable by flattening the slope and hindering water and soil from flowing downward. They can direct the flow of water in a direction you want it to go and prevent runoff from wearing down or eroding the landscape. They also serve an aesthetic purpose by making an area look neat and clearly defined.

The pressure behind a retaining wall, holding back tons of soil and water, can be enormous. Even a well-constructed wall can fail if a proper outlet for runoff is overlooked; the water pressure can make the wall fall apart.

Walls made of concrete retaining wall blocks less than 3 feet tall can be built by do-it-yourselfers, but anything taller requires a professional. Considerable knowledge and experience are needed before undertaking such a project. Research local building codes, especially if erosion and runoff are concerns.

The instructions and materials in this guide are for a retaining wall made of specialized concrete blocks made intentionally for retaining wall projects. It takes roughly 20 to 30 hours, depending on your skill level, if you have assistance, the weather, the materials used, and the wall length.

Before You Begin

Before installation, you must decide whether to build the structure or hire someone else. If you have limited DIY experience, do not attempt to build a retaining wall beyond 3 feet tall—anything taller requires a professional. Also, significant runoff issues will require professional assistance. If water runoff is a problem in your area, particularly your land, install a perforated drain pipe behind your retaining wall before backfilling.

Review local building codes, determine your soil type (organic or dense soils create too much pressure), and understand your climate (gravity and frost are the most significant factors) and runoff pattern.

Do not overlook the aesthetic component of retaining walls. Select a material that is in sync with your overall design goals. The material you choose will depend on factors such as your design tastes, the function(s) of the wall, and cost. Retaining walls made of materials other than concrete retaining wall blocks requires the assistance of a professional.

• Concrete blocks: Some concrete blocks are made to build sturdy retaining walls. These interlocking blocks have a flange on the back side designed to slip neatly over the course below, allowing the structure to slope backward slightly as you lay course after course.
• Stone: If going for a more natural look in your landscape design, choose a beautiful, raw material like natural hardscaping features, such as stone. Techniques for building a stone retaining wall differ from those for making a regular stone wall. This option is pricier than concrete blocks.
• Pressure-treated timber or wood: Pressure-treated timber and lumber are prevalent in rural settings. Using wood is another costly alternative.
  
• Poured concrete: Poured concrete (reinforced with rebar) is commonly used in commercial settings.
  

Retaining Wall Cost

The costs to build a retaining wall in the United States can cost between $3,000 to $9,000, with an average cost of about $6,000, according to Angi. The price is determined by height, length, style, and finish.

For the cheapest retaining wall material, you can build a 2-foot-tall vinyl retaining wall that costs about $10 per linear foot. In contrast, a 2-foot-tall steel or stone retaining wall can cost about $200 per linear foot. 

Concrete blocks are an excellent middle-of-the-road material, averaging about $80 per linear foot for a two-foot wall ($120 for a 3-foot wall). So, a 10-foot-long wall that is 3 feet tall will cost roughly $1,200.

Safety Considerations

Always call the "Call Before You Dig" number before building a retaining wall, so you don't damage buried utility lines.

Shoveling dirt and gravel can be hard on the back. Even if you haven't had problems in the past, you do not want this project to expose an underlying back issue. Invest in a good quality back brace.

Wear safety gloves when handling rock, concrete, or shoveling to protect your hand from cuts and abrasions. When working with stone dust and crushed stone, wear a facemask to prevent the fine particulate matter from entering your breathing passages. Goggles are imperative when shoveling crushed stone that can inadvertently kick up and ricochet toward your face as you're stooping down to shovel.