Types of Retaining Walls

Struggling with soil erosion or uneven landscapes in your garden?

These issues can damage your property, make outdoor spaces unusable, and create long-term maintenance headaches.

Retaining walls offer an effective way to manage soil and create aesthetically pleasing, functional outdoor areas. Discover the different types of retaining walls and how they can transform your landscape.

Types of Retaining Walls

Discover the diverse world of retaining walls with our comprehensive guide. From the robustness of gravity walls to the structural flexibility of hybrid designs, explore the various types and their best applications. Whether landscaping a garden or engineering a significant infrastructure project, find the perfect solution for your soil retention needs.

1. Gravity Retaining Walls

Gravity retaining walls rely on their mass and weight to hold back soil. They do not need additional reinforcement when constructed from heavy materials like concrete, stone, or masonry. Their strength comes from their substantial weight, counteracting the lateral pressure of the soil.

Designed with a battered profile—thicker at the base and tapering towards the top—these walls enhance stability by lowering the centre of gravity and resisting overturning and sliding forces. 

Suitable for heights up to three metres, taller walls may require a more comprehensive base or mechanical stabilisation.

Key advantages include simple construction and cost-effectiveness without needing complex engineering. However, the weight and durability of materials must be considered for long-term performance and safety.

Gravity retaining walls provide a robust and enduring soil retention solution, ideal for residential and commercial applications.

2. Cantilever Retaining Walls

Cantilever retaining walls use a horizontal beam to support soil. They feature a thin stem and a base slab forming an inverted T-shape. 

The base slab has two parts: the heel, which extends under the soil, and the toe, which projects outward. The weight of the soil on the heel provides stability, preventing overturning and sliding, while the toe helps balance the structure.

Made primarily from reinforced concrete, these walls are suitable for heights up to six metres. They require precise engineering and construction for stability and effectiveness.

Key benefits include efficient material use, making them a cost-effective choice for taller applications. Cantilever retaining walls, commonly used in commercial projects and infrastructure like highway overpasses, offer a strong and durable solution for soil retention.

3. Sheet Piling Retaining Walls

Sheet-piling retaining walls use thin, interlocking sheets of steel, vinyl, or wood driven into the ground to form a continuous barrier. These sheets are often corrugated for added strength and stiffness, ideal for soft soil conditions and tight spaces.

Sheet piling walls are commonly used in waterfront structures, coastal defences, and temporary excavations. They are installed using a vibratory hammer or hydraulic press. The sheets interlock to create a stable wall, with depth determined by soil conditions and required height.

Key advantages include quick installation and ease of removal, which are suitable for temporary projects. The materials can be recycled or reused, enhancing their cost-effectiveness and sustainability.

Sheet piling retaining walls provide a versatile and efficient soil and water retention solution in various construction projects.

4. Anchored Retaining Walls

Anchored retaining walls use anchors or tiebacks driven deep into the soil behind the wall for added stability. These walls are ideal for tall structures and high lateral pressures.

Anchors are installed using drilling techniques and expanded at the end with mechanical means or pressure grouting to grip the soil. This ensures the wall stays securely in place under significant loads.

Constructed from concrete, steel, or timber, anchored walls are suitable for permanent and temporary applications, such as deep excavations, bridge abutments, and harbour structures.

Key advantages include support without large base widths, making them ideal for restricted spaces. The anchors can be tensioned after installation for added stability.

Anchored retaining walls provide a robust and flexible solution for challenging soil conditions and high-load applications, ensuring long-term stability and safety.

5. Bored Pile Retaining Walls

Bored pile retaining walls are constructed by drilling deep holes into the ground and filling them with concrete. They consist of vertical piles interconnected by a horizontal structural element, such as a beam or slab, forming a continuous wall.

The drilling process uses rotary drilling equipment to ensure precise placement of the piles, and their diameter and depth are determined by factors such as soil conditions, groundwater level and required wall height.

These walls offer exceptional structural integrity and can withstand high lateral pressures, making them suitable for use in urban environments, deep excavations, and seismic zones.

Bored pile retaining walls are highly versatile, accommodating various soil conditions and complex geometries to meet specific project needs.

They provide a durable and efficient solution for soil retention, ensuring long-term stability and safety in challenging construction environments.

6. Gabion Retaining Walls

Utilising wire mesh baskets filled with rocks or other durable materials, gabion retaining walls offer a sustainable solution for soil retention. These baskets, known as gabions, are stacked atop one another to create a retaining wall structure.

The wire mesh, typically galvanised steel, provides strength and corrosion resistance, while locally sourced materials like rocks or recycled concrete fill the baskets, enhancing the wall’s sustainability.

Gabion walls offer flexibility in design and construction, accommodating curves and variations in wall height. They find utility in diverse environments, from slopes to riverbanks and coastal areas.

Installation is straightforward and cost-effective, requiring minimal foundation work compared to other retaining walls. Additionally, their permeable nature enables natural drainage, reducing hydrostatic pressure behind the wall.

Gabion retaining walls are a popular landscaping choice, prized for their environmental sustainability and design versatility. They are durable, aesthetically pleasing, and effective in erosion control.

7. Crib Retaining Walls

Crib retaining walls use interlocking rectangular or square modules made from timber, precast concrete, or steel. These modules stack together to form a sturdy wall.

Their interlocking design ensures exceptional stability and quick construction. Filled with compacted soil or aggregate, they reinforce the wall.

Crib walls suit applications like road embankments and landscape terracing, adapting to straight or curved configurations.

Their strength allows them to withstand heavy loads and erosion, with easy replacement of damaged sections for long-term durability and cost-effectiveness.

Crib retaining walls provide a versatile and robust solution for soil retention, adding structural support and aesthetic appeal to construction projects.

8. Hybrid Retaining Walls

Hybrid retaining walls merge features from various types, like gravity, cantilever, or anchored walls, to suit specific project needs. They offer a tailored solution by integrating techniques based on site conditions and desired outcomes.

For instance, a hybrid wall might combine the stability of a gravity wall with the reinforcement of soil nails or anchors for added strength. Engineers use advanced modelling to determine the best mix of methods and materials, considering factors like soil properties and project goals.

These walls provide enhanced performance and versatility compared to single-type walls. They’re customisable to address specific challenges while ensuring structural integrity and cost-effectiveness.

Hybrid retaining walls represent a modern approach to soil retention, offering tailored solutions for complex projects.

Choosing the Right Retaining Wall

Selecting the appropriate retaining wall for your project requires thoroughly assessing various factors. 

• Site Conditions: Evaluate soil type, groundwater level, and slope gradient to determine the most suitable wall.
• Height and Load-Bearing Requirements: Gravity walls are ideal for low to moderate heights, while cantilever or anchored walls are better for taller structures or high lateral pressures.
• Available Space and Aesthetic Preferences: Consider design flexibility and how well the wall blends with the surroundings. Gabion or crib walls offer more natural aesthetics, while concrete walls provide a contemporary look.
• Construction Costs and Maintenance: Factor in initial costs, long-term maintenance requirements, and durability. While some walls may have higher upfront costs, they could offer lower maintenance and longer lifespan, making them cost-effective in the long run.
• Regulatory Compliance: Ensure the chosen wall complies with local building codes and regulations, especially regarding height, setback requirements, and environmental considerations.
• Project Timeline: Consider the construction timeline and any constraints that may affect the choice of retaining wall, such as weather conditions or site access.

Maintenance and Care

Your retaining wall is more than just a functional structure—it’s an investment in your property’s landscape. But without the right care, even the sturdiest wall can fail. Discover how regular maintenance can safeguard your wall’s strength and appearance for years.

• Inspect regularly: Check your retaining wall frequently for cracks, bulging, or leaning. These signs may indicate structural issues that require immediate attention.
• Maintain Drainage: Ensure that the drainage system is free from debris. Proper drainage prevents water buildup, which can increase pressure on the wall and lead to structural failure.
• Trim Vegetation: Keep plants and trees around the wall trimmed. Overgrown roots can penetrate the wall, causing destabilisation and potential damage.
• Protect Against Freeze-Thaw Cycles: In colder climates, seal cracks and maintain drainage to protect your wall from the damaging effects of freeze-thaw cycles.
• Monitor Timber Walls:  Look for signs of rot or insect damage for timber retaining walls. Treat the wood as necessary to prolong its lifespan.
• Repoint and Seal: Regular repointing and sealing may be required for concrete and stone walls to maintain the wall’s integrity and prevent deterioration.

Conclusion

We’ve explored various types of retaining walls, each suited to specific applications. From the strength of gravity walls to the versatility of hybrid designs, understanding the right choice for your project is vital. Remember to select wisely and maintain regularly for longevity.