Flood Defence Walls
Precast concrete wall systems for permanent and temporary flood protection
Why Choose Precast for Flood Defence
Flooding is one of the most disruptive risks for construction projects, infrastructure, and communities. Precast concrete walls offer a proven, adaptable way to control water, protect property, and keep projects on track.
Whether you need a permanent retaining wall with sealed joints or a quick barrier solution for emergency response, precast systems help you move faster, reduce disruption, and allow you to build with confidence.
Key Benefits of Precast Flood Defence Walls
Fast installation – Modular units are delivered ready to install, enabling protection to be established in hours or days, not weeks.
Flexible sealing options – From general weatherproof mastic seals to specialised jointing systems such as Sikadur-Combiflex® or hydrophilic strips, precast walls can be detailed to achieve the right level of watertightness.
Durability in exposed environments – Manufactured with C50/C60 concrete, our walls are designed for challenging conditions, including coastal sites and areas with airborne salts.
Temporary or permanent – Solutions vary from quick-deploy barrier systems to cast-in retaining walls intended for long-term flood defence.
Adaptable layouts – Straight runs, corners, and varying heights can be achieved with modular units, making it easier to follow site boundaries or riverbanks.
Suitable Products For Flood Defence Walls
Best for: Flexible, continuous flood walls along riversides, canals, or site perimeters where a steel frame is part of the design.
Prestressed panels installed between steel columns are one of the most versatile ways to build flood defence walls. They can be installed into the web or attached to the outside face of UC/UB steels, with positioning on the outside face making it easier to seal the vertical joints against water ingress.
Individual heights up to 1.5m; panels can be stacked to build taller walls
Lengths range from 2.5m to 6m to fit steel centres and reduce the number of joints
Compatible with sealing systems from simple mastic to watertight tape solutions.
Panels delivered to site ready for installation, saving time during flood defence works
Best for: Permanent flood defence walls without steel frames, clean straight runs, and sites that need a smooth, easy-to-maintain face.
Vertical cantilever panels are installed into a reinforced trench footing to form a permanent, flush-faced wall. Each panel is placed into cradles, temporarily propped, and tied into the footing reinforcement. Once the concrete cures, the wall becomes self-supporting, creating a strong cantilever action that makes it suitable for long-term flood defence.
Installed into reinforced foundations with props removed after curing for full cantilever action
Suitable for wall heights up to 6 m above ground and surcharge loads up to 20 kN/m², depending on thickness and design
Tongue-and-groove alignment allows simple sealing with products like Pro-3 for weatherproofing or tape systems for watertightness
Smooth mould finish to the exposed face, with options to increase reinforcement cover for extended design life
Best for: Critical flood protection projects requiring secure joint sealing and extended design life.
Cast-in walls offer the highest level of watertight protection in our range. Installed into new foundations with a hydrophilic joint detail, they are ideal for permanent flood defence schemes with long-life requirements.
Installed into foundations with cast-in joint details for improved watertightness
Compatible with hydrophilic strip sealing systems for long-term flood defence
Reinforced concrete design with up to 100-year design life
Smooth mould finish suitable for public-facing infrastructure
Best for: Flexible, continuous flood walls along riversides, canals, or site perimeters where a steel frame is part of the design.
Interlocking blocks that stack without fixings, Allegro® units offer a practical solution for quick, temporary flood protection. They can be redeployed elsewhere once the risk has passed.
Dry-stacked system with interlocking nibs
Fast deployment using standard site plant
Reusable across multiple sites, making them cost-effective
Can form diversion walls or supplement permanent defences in high-risk areas
Best for: Temporary flood diversion or channelling water away from critical infrastructure.
These long precast barriers feature a unique interlocking pivot joint that allows them to be set at angles of up to 90°. While they are not watertight, they can redirect or slow water flow when lined, making them useful for emergency flood management.
3.85m long units with curved interlocking ends
Install at straight runs or angled layouts for flexible barrier design
Strong precast design, with each unit weighing over 2 tonnes
Can be lined for improved water control in temporary defence schemes
Best for: Large-scale or complex schemes needing tailored engineering solutions.
Some flood defence projects require more than standard units. We design and manufacture bespoke precast solutions tailored to each project, whether that’s a custom wall profile, special reinforcement, or integrated sealing details.
Custom moulds and reinforcement detailing to project specifications
Specialist sealing systems and joint detailing available
Option for reduced-carbon concrete mixes
Design life extended to 100 years when required
What to Consider Before You Build a Flood Defence Wall
- Required Level of Watertightness – Decide early whether your project needs general flood resistance or a fully watertight structure. Options range from weatherproof mastic seals to high-performance systems like Sikadur-Combiflex® or hydrophilic strips for long-term protection.
- Site Conditions & Exposure Class – Flood defences often sit in coastal or riverside environments where airborne salts, freeze–thaw cycles, or severe weather conditions are common. Precast walls made with C50/C60 concrete can be detailed to match these exposure classes, and reinforcement cover can be increased if needed.
Foundation Type & Ground Preparation – Different systems require different base designs: Horizontal panels rely on UC/UB steel columns on pad foundations. Vertical cantilever walls need reinforced trench footings. HD cast-in walls are incorporated into new concrete slabs for maximum stability. Getting foundation levels and steelwork layouts correct leads to smoother installation and better joint alignment.
- Surcharge Loads & Structural Performance – Consider any surcharge from retained ground, vehicles, or pedestrian areas alongside hydraulic forces during flood events. Cantilever walls can withstand up to 20 kN/m², while prestressed panels and HD cast-in systems offer greater design flexibility and an extended design life.
Wall Height, Freeboard & Local Requirements – Flood defence schemes typically specify minimum wall heights or freeboard above design water levels. Precast options can reach up to 6m depending on the system, and modular units can be stacked as necessary. Confirm requirements with the local authority or Environment Agency early.
Joint Detailing & Seal Compatibility – Joint design is essential. Tongue-and-groove alignment on vertical cantilever walls makes sealing easier, while cast-in options with hydrophilic strips offer the best watertightness. Select sealing products based on long-term exposure and maintenance expectations.
Access & Installation Logistics – Flood defence works often run along riverbanks, roads, or narrow boundaries. Plan lifting routes for HIABs, telehandlers, or cranes, and consider how the works interface with watercourses, existing structures, or public areas.
Temporary vs Permanent Protection – If you need rapid deployment or short-term flood diversion, modular Allegro® blocks or Staunton® barriers are easy to install and can be redeployed afterwards. Permanent solutions are better suited to cast-in or cantilever systems where long-term resilience is required.
Flood Defence Questions We Get All The Time
Yes – joints between units can be sealed depending on project needs. Options include general-purpose mastic for weatherproofing, or systems such as Sikadur- Combiflex® and hydrophilic strips for long-term watertight performance.
Foundations vary depending on the product. Vertical cantilever and cast-in walls require prepared bases, while modular blocks and barriers can often be installed directly onto compacted ground. Your engineer will confirm the right foundation design for your site.
Yes. Our concrete mixes and reinforcement details can be tailored to account for exposure classes that include airborne salts and freeze–thaw conditions. This makes precast a reliable choice for coastal or riverside flood defence.
Yes – units such as Allegro® blocks and Staunton® barriers can be lifted and redeployed for other site applications, making them a sustainable and cost-effective option for emergency works.
Standard units are designed for 50 years, with cast-in and bespoke solutions offering up to 100 years, depending on detailing. Always confirm project requirements with your engineer.