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Not all retaining walls are the same. The type of wall that is right for your project depends on the height of retained ground, the ground conditions, the loads being applied, and the space available to build. Getting this decision right at the design stage saves significant time and cost during construction.
This guide covers the main types of reinforced concrete retaining wall used in the UK, explains when each type is appropriate, and sets out what to consider when specifying one for a residential or commercial project.
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What is a Reinforced Concrete Retaining Wall?
A retaining wall is a structure that holds back a mass of soil or other material on one side, preventing it from sliding or collapsing. A reinforced concrete retaining wall achieves this using steel-reinforced concrete — the same combination of materials used in reinforced concrete frames, slabs, and foundations.
The reinforcement steel (rebar) gives the concrete the tensile strength it needs to resist the bending forces generated by the retained ground. Without reinforcement, plain concrete is too brittle to perform reliably in this role. Reinforced concrete retaining walls are among the most durable and structurally capable retaining structures available and are the standard choice for commercial and infrastructure projects.
Types of Reinforced Concrete Retaining Wall
1. Gravity Retaining Wall
A gravity retaining wall relies on its own mass and weight to resist the lateral pressure of the retained ground. It is typically a thick, relatively plain concrete structure with minimal internal reinforcement. Gravity walls are best suited to lower heights — generally up to around 1.5m of retained ground — where the volume of concrete required to provide sufficient mass is not prohibitive.
They are simple to design and build but become uneconomical at greater heights, where the volume of concrete required makes other wall types more cost-effective.
Best for: Lower-height walls, simple ground conditions, projects where speed of construction is a priority.
2. Cantilever Retaining Wall
A cantilever retaining wall is the most common type of reinforced concrete retaining wall for both residential and commercial projects. It uses a structural base slab and an upstanding stem to resist the forces from the retained ground. The base slab extends back under the retained material — the weight of the soil sitting on the heel of the base slab helps the wall resist overturning.
Cantilever walls are efficient in their use of concrete and steel and are appropriate for a wide range of heights, typically from 1.5m up to around 6m or 7m of retained ground. They require a properly designed base slab, which means adequate founding depth, and they need space behind the wall face for the heel of the base to extend into.
Best for: Residential walls over 1.0m, most commercial retaining applications, basement perimeter walls.
3. Counterfort Retaining Wall
A counterfort retaining wall is a variation of the cantilever wall in which vertical concrete ribs (counterforts) are added behind the stem at regular intervals. These counterforts tie the stem and base slab together and significantly reduce the bending moments in both elements, allowing thinner sections to be used for taller walls.
Counterfort walls are used for taller structures where a pure cantilever design would require very thick concrete sections that become uneconomical. They are less common on residential projects but appear regularly in commercial and infrastructure work.
Best for: Taller walls above 6m to 7m, infrastructure and highway applications, large commercial schemes.
4. Basement Retaining Wall
A basement retaining wall forms the structural perimeter of a below-ground space. It must resist the lateral pressure of the surrounding ground while also supporting the loads of the structure above. In most residential basement conversions, the basement wall is a reinforced concrete cantilever structure designed to span between the base slab and the ground floor slab above.
Basement retaining walls need to be designed carefully for waterproofing as well as structural performance. The concrete specification, construction joints, and any additional waterproofing system all need to be coordinated with the structural design.
Best for: Residential basement conversions, below-ground car parks, plant rooms, and below-ground commercial spaces.
5. Propped and Anchored Retaining Walls
Where space is constrained and the heel of a cantilever base slab cannot extend behind the wall, propped or anchored wall systems can be used. These walls use ground anchors, tie rods, or structural props to resist the lateral forces that would otherwise be handled by the base slab geometry. They are more complex to design and construct but allow retaining walls to be built in very tight conditions.
Best for: Constrained urban sites, situations where base slab extension is not possible, deep excavation support.
Comparison Summary
| Wall Type | Typical Retained Height | Complexity | Best Application |
|---|---|---|---|
| Gravity | Up to 1.5m | Low | Simple residential walls |
| Cantilever | 1.5m to 6m+ | Medium | Most residential and commercial |
| Counterfort | 6m+ | High | Tall commercial / infrastructure |
| Basement perimeter | Varies | High | Basement conversions and below-ground structures |
| Propped / anchored | Varies | High | Constrained sites and deep excavations |
Drainage: An Essential Part of Any Retaining Wall
Whichever wall type is specified, drainage behind the wall is not optional. Water building up in the retained ground creates hydrostatic pressure that adds significantly to the forces the wall must resist. A wall designed without accounting for drainage can fail in wet conditions even if the structural design is otherwise sound.
A correctly designed retaining wall drainage system typically includes:
- A granular free-draining layer (usually 300mm to 600mm) placed directly behind the wall face
- Weep holes through the wall at low level to allow water to escape
- A perforated pipe drain at the base of the wall connected to a suitable outfall
The drainage design should be specified by the structural engineer alongside the wall design and built in sequence with the wall construction — not added as an afterthought.
When Do You Need a Specialist Retaining Wall Contractor?
Any reinforced concrete retaining wall should be built by a contractor with direct experience of in-situ reinforced concrete construction. Retaining walls are structural elements — the consequences of incorrect reinforcement placement, inadequate concrete compaction, or poorly constructed formwork can be serious.
Look for a contractor who:
- Has direct experience of in-situ reinforced concrete work (not just groundworks or brickwork)
- Can work from structural engineer drawings and liaise with the engineer if questions arise on site
- Employs CSCS-qualified operatives experienced in formwork and steel fixing
- Provides a clear, itemised quotation covering exactly what is and is not included
Coral Structures carry out reinforced concrete retaining wall construction for residential and commercial clients across Bristol, Bath, Gloucestershire and the wider South West. For indicative pricing, see our retaining wall cost guide. Get in touch with your drawings or project details for a detailed written quotation.
Frequently Asked Questions
For most residential and commercial projects in the UK, the cantilever reinforced concrete retaining wall is the most widely used type. It offers good structural efficiency across a wide range of heights and is appropriate for the majority of domestic and commercial retaining applications.
Planning permission is generally not required for retaining walls below 1.0m adjacent to a highway or below 2.0m elsewhere, provided they are not on a listed building or in a conservation area. Building Regulations approval is required for any structural retaining wall. Check the Planning Portal or with your local planning authority if you are unsure.
Foundation depth depends on the ground conditions and the height of the retained material. A structural engineer will specify the founding depth based on ground investigation data. As a general guide, cantilever retaining wall foundations are typically 600mm to 1,000mm deep for lower walls and deeper for taller structures.
Most reinforced concrete retaining walls in the UK are built using C32/40 or C35/45 concrete with a w/c ratio appropriate to the exposure class. The structural engineer will specify the concrete grade, cement type, cover to reinforcement, and any admixtures required for the specific site conditions.
Yes, but it requires careful design to manage the loads and movement between the new wall and the existing structure. A structural engineer must assess the impact on both elements. In tight proximity to existing buildings, temporary propping or phased construction may be required.