9 Different Types of Retaining Walls To Know

Retaining walls are important structures designed to hold back soil and prevent erosion. You will often find them on properties with sloped terrain, where they create level surfaces for patios, gardens, or driveways. Beyond their functional purpose, retaining walls can also add significant aesthetic value to a landscape. Understanding the various types available is crucial for selecting a wall that meets your structural needs and design preferences.

Making the right choice involves considering factors like the height of the wall, soil conditions, budget, and the desired appearance. Each type of retaining wall offers a unique combination of strength, durability, and style. From the simple gravity wall to complex anchored systems, the options are diverse. This overview explores the most common types of retaining walls, detailing their construction, benefits, and ideal applications to help you make an informed decision for your property.

Gravity Retaining Walls

Gravity retaining walls rely on their own mass to resist the pressure of the soil behind them. These walls are typically built from heavy materials such as stone, concrete blocks, or pavers. The sheer weight of the wall holds the earth in place, making it one of the most straightforward types of retaining walls. They are often built with a slight backward lean, known as a batter, which uses gravity to improve their stability further. Because they do not require complex reinforcement, gravity walls are a popular choice for do-it-yourself projects and shorter wall heights, generally under four feet.

Cantilevered Retaining Walls

Cantilevered retaining walls use a reinforced concrete footing to resist soil pressure. The wall itself is a relatively thin stem of concrete or masonry that is attached to a large, structural footing shaped like an "L" or an inverted "T." The weight of the backfill soil on the heel of the footing helps anchor the entire structure, providing the necessary leverage to counteract the lateral force of the earth. These walls require less material than gravity walls of the same height, making them a more economical choice for heights ranging from 10 to 20 feet. Their design involves steel rebar reinforcement, which provides the tensile strength needed to handle significant loads.

Sheet Pile Retaining Walls

Sheet pile retaining walls are a common solution in areas with soft soils and tight spaces. This type of wall consists of long, thin sheets of steel, vinyl, or wood that are driven directly into the ground. These sheets interlock to form a continuous barrier against the soil. For shorter walls, the sheet piles can cantilever on their own. For taller applications, they often require an anchor, such as a tie-back rod connected to a plate or deadman anchor buried in the stable soil behind the wall. Sheet piling is particularly useful for waterfront structures and temporary deep excavations because it can be installed quickly.

Anchored Retaining Walls

An anchored retaining wall utilizes cables or rods to provide additional support against soil pressure. These anchors are driven deep into the earth behind the wall and are expanded mechanically at the end to create a secure hold. Professionals use this technique with various wall types, including concrete and sheet pile walls, allowing them to be built taller or thinner than they otherwise could be. The anchors essentially tie the wall to a stable mass of soil, preventing it from tipping or sliding. This method is highly effective for supporting heavy loads or stabilizing particularly tall slopes. Proper installation and tensioning of the anchors are important for the wall's long-term performance.

Piled Retaining Walls

Piled retaining walls are constructed by driving piles, such as concrete, steel, or timber, in a row to form a retaining structure. There are two main variations: contiguous and secant pile walls.

• Contiguous pile walls have small gaps between each pile. They are suitable for areas where some water seepage is acceptable.

• Secant pile walls are formed by installing interlocking primary (unreinforced) and secondary (reinforced) piles. This creates a continuous, watertight barrier, making it an excellent choice for deep excavations in urban areas or for projects requiring significant water control, such as basement waterproofing in Ann Arbor.

These walls are installed before any major excavation begins, providing soil support from the start.

Gabion Retaining Walls

Gabion walls are rectangular wire-mesh baskets filled with rocks or other durable materials. These baskets are stacked to form a massive, permeable gravity wall. The weight of the rock-filled baskets provides stability, while the porous nature of the structure allows water to drain through freely. This excellent drainage prevents the buildup of hydrostatic pressure, which is a common cause of retaining wall failure. Gabion walls are flexible, making them well-suited for unstable soil conditions where rigid concrete walls might crack. They also have a rustic, natural appearance that can blend well with many landscapes.

Counterfort Retaining Walls

Counterfort retaining walls are a variation of the cantilevered wall, designed for heights exceeding 20 to 25 feet. They include thin, triangular concrete webs known as counterforts, which are placed at regular intervals along the back of the wall. These counterforts connect the wall stem to the footing, acting like buttresses. They provide the stem with additional rigidity and transfer the lateral soil pressure more effectively to the base. Because the counterforts are on the back side, the backfill hides them, leaving a clean, flat face on the exposed side of the wall.

Natural Stone Retaining Walls

Natural stone retaining walls are a type of gravity wall prized for their timeless beauty and durability. They can be constructed using either mortar (a wet-laid wall) or without (a dry-stacked wall). Dry-stacked walls rely on the careful placement and friction between stones for stability and have natural gaps that allow for excellent drainage. Wet-laid walls use mortar to bind the stones, creating a stronger, more rigid structure. While more labor-intensive and costly to build, natural stone walls offer a classic aesthetic that can enhance any property.

Timber Retaining Walls

Timber retaining walls offer a natural and often more affordable option for retaining soil. They are constructed from pressure-treated lumber or railway ties that are resistant to rot and insect damage. Masons typically build these walls as gravity structures for shorter heights. Proper drainage is especially important for timber walls to prolong their lifespan, which is generally shorter than that of concrete or stone walls. Despite this, their rustic look and lower initial cost make them an attractive choice for many landscaping projects, particularly in garden settings.

Choosing the Right Wall for Your Project

Selecting the appropriate retaining wall depends on a thorough evaluation of your site's conditions and project goals. Consider the height of the slope, the type of soil, your budget, and the overall aesthetic you wish to achieve. For smaller, straightforward applications, a gravity or segmental block wall might be sufficient. For more challenging sites with tall slopes or poor soil, a cantilevered, anchored, or piled wall may be necessary. Consulting with a qualified engineer or contractor is always recommended to make sure your retaining wall is designed and built to be safe, durable, and effective.