
Duo™ Interlocking Blocks
Manufactured Exclusively in the UK by Elite Precast Concrete
Elite Precast Concrete is the sole UK manufacturer of Duo™ interlocking concrete blocks, delivering a robust, versatile and cost-effective solution for a wide range of industrial, commercial and agricultural applications.
Designed for strength, flexibility and ease of installation, Duo™ concrete blocks are ideal for constructing retaining walls, storage bays and segregation systems without the need for permanent foundations.
What are Duo™ Interlocking Blocks?
A Duo interlocking block is a large precast concrete block designed to lock together with neighbouring blocks, a bit like oversized children's blocks. They’re commonly used to build walls, storage bays, segregation walls, barriers and other modular structures.
The top and bottom of each block have matching profiles so that when blocks are stacked, the profiles interlock and resist sideways movement. As the system is modular, walls can usually be assembled relatively quickly and can often be dismantled and reconfigured later.

Why Choose Elite Precast
With decades of precast expertise, in-house engineering support and a proven delivery record on projects of every scale, Elite Precast is the partner specifiers trust. We pair robust, repeatable manufacturing with the flexibility to engineer bespoke solutions when a standard product will not do.
Key Features & Benefits
Manufactured from high-quality precast concrete, Duo™ blocks create exceptionally durable and fire-resistant walls suitable for demanding environments.
Full specifications
Installation Overview
Always inspect lifting pins and blocks for wear, corrosion or cracking before lifting reused blocks.
Wind loading can affect single-skin, freestanding walls over 4.05m high.
Avoid direct impact from mobile plant; in higher-risk environments, strapping top layers can improve stability.
The Duo interlocking block range includes three sizes:
One connector
Two connector
Three connector
The standard block (BL2) measures 1200mm x 600mm x 450mm and weighs 750kg.

Typical Loading Guidance
Loading figures are for guidance only; a qualified structural engineer should be consulted where required. Retained materials should be allowed to naturally form against the wall during stacking. Load tables are based on typical material densities and angles of repose. All walls must be constructed on a suitable base.
Additional example calculations are available within our Elite Knowledge section, called Stability & Loading Calculations.
DUO IMAGE NEEDS ADDING

Compliance & Technical Support
Duo™ interlocking concrete blocks are manufactured in accordance with BS EN 1992-1-1:2004 – Design of Concrete Structures.
As experienced precast concrete manufacturers, Elite Precast Concrete provides:
Design and installation guidance
Stability and load-bearing advice
Structural and foundation design reviews (available on request)
Before commencing any project, we recommend reviewing our Stability & Loading Calculations Directory, held within Elite Knowledge, which provides guidance on:
Maximum wall heights
Stored material types and densities
Ground bearing capacity and foundation suitability

Safety & Responsibility
Blocks may be damaged through impact during construction. Elite Precast Concrete cannot accept responsibility for damage after delivery and sign-off.
Wind loading can affect the stability of single skin, stand-alone Duo block walls above 4.05m high. If in doubt, always get it checked by a qualified structural engineer.
Avoid direct impact from mobile plant; in higher-risk environments, strapping top layers, can help to mitigate the risk.
It is the customer's responsibility to ensure appropriate structural checks are completed prior to installation.
Prior to lifting older or pre-used blocks check for cracks, lifting pin wear or corrosion. If the block is cracked or the pin is worn it could fail when being lifted.

Applications
Duo™ interlocking concrete blocks are engineered to perform across diverse environments and material types, including:
Retaining and pendine walls
Salt and aggregate storage bays
Compost, grain and woodchip segregation walls
Waste and recycling bays (RDF, black bag waste, white goods)
Light scrap metal storage
Temporary works and modular structures
Above-ground, no-dig fencing and hoarding systems
Fire-resistant partition and perimeter walls
Art installations and landscaping
Their modular design allows structures to be easily adapted, dismantled or relocated as site requirements change.
Temporary Structures with Commercial Advantages
External storage bays built using Duo™ interlocking blocks are typically classified as temporary structures. In many cases, this means planning permission is not required, provided the structure can be dismantled and relocated. We always recommend confirming requirements with your local authority.
Choosing a temporary structure instead of a permanent build can offer several benefits:
Reduced or zero business rates
Lower construction costs
Faster installation and future flexibility

Finish & Appearance
Please note that the concrete finish of our interlocking blocks is classed as basic in accordance with the National Structural Concrete Specification for Building Construction. Under this specification there is no requirement other than the concrete being adequately compacted to achieve the density and compressive strength required.
Decorative concrete walling options are available with our Retainer-Rock and Vee-Rock walling, which can be found within our Retaining Wall section.

Gallery
Project solutions

Duo Blocks for Fertiliser and Feed Storage
Secure, durable storage bays for bulk fertiliser and feed in demanding farm environments.

Duo Blocks for General Farm Partitioning
Strong dividing walls and segregated areas to improve farm organisation, safety and efficiency.

Duo™ Blocks for Grain and Crop Bays
Strong, durable storage bays for bulk grain and crops in agricultural environments.

Duo™ Blocks for Silage Storage
Strong retaining walls and silage clamps with durability, stability and rapid installation.

Duo™ Blocks for Waste Segregation Areas
Strong retaining walls and clearly defined bays for organised, compliant waste segregation.
Important downloads
- Duo block 2.7m high 0.8t per m³ calcsPDF750 KB
- 572 03 Duoblock Design SummaryPDF624 KB
- Duo block 1.8m high various materials calcsPDF457 KB
- Duo 2.7m Typical Foundation DetailPDF364 KB
- Duo Blocks 4.05 high Load Case 1 Design SummaryPDF480 KB
- Duo block – Storing baled paper cardboard – essential guidancePDF300 KB
- Duo blocks 4.05m high indoor single skin wall – 0.6 tonnes per m3 calculationsPDF466 KB
- EPC TYP 005 Aggregate Bays 20kN m3 x 2.25m DuoPDF1.2 MB
- Duo 2.7m retaining wallPDF99 KB
- Duo Bay Typical LoadsPDF1.5 MB
- Duo block 3.15m high 1.0t per m³ calcsPDF752 KB
- Duo Blocks earth retaining 1.8m high Design SummaryPDF298 KB
- Duo blocks 4.05m high indoor single skin wall – 0.34tonnes per m3 calculationsPDF464 KB
- Duo block 0.9m high 0.8t per m3 calcsPDF740 KB
- Duo Blocks 4.05 high Load Case 2 Design SummaryPDF477 KB
- EPC TYP 002 Fire Wall 3.15m DuoPDF397 KB
- Impact Load Calculation Summary 2.7 Duo BlocksPDF156 KB
- Typical loads Duo Legato and VeePDF4.9 MB
- EPC TYP 004 Storage Bays 18kN m3 x 1.8m DuoPDF911 KB
- Duo block 2.25m high 0.8t per m³ calcsPDF757 KB
- Duo Blocks earth retaining 2.25m high Design SummaryPDF290 KB
- Shear Force Legato Duo BlocksPDF94 KB
- Duo block earth retaining 0.9m High Calculation SummaryPDF347 KB
- Duo blocks – 1.8m high Bund wall calculationsPDF378 KB
- 9 Block High Duo Black Bag Waste Single skin Calculation SummaryPDF253 KB
- Duo 2.7m High Load Diagram amended notesPDF301 KB
- Duo block 3.15m high dry loam 1.3 tonnes per m3PDF254 KB
- EPC TYP 003 Shredded Bales Storage Bay 19.2m x 3.15m DuoPDF699 KB
- Duo block 3.15m high 0.34t per m³ calcsPDF393 KB
Case Studies & Blogs

Blog
How Elite Precast helps small waste operators meet new fire-protection rules

Blog
Benefits of reducing water logging in material storage and water management within the UK Quarrying Industry

Blog
Reliable storage bay solutions and the cost-saving benefits

Blog
Flood Protection with interlocking blocks

Case study
Duo™ Blocks Create an Art Installation on Newcastle Quay

Blog
The cost-saving benefits of reliable storage bay solutions

Blog
Elite Precast Concrete expands on fantastic foundations
Frequently Asked Questions
What are Duo™ interlocking concrete blocks used for?
Duo™ blocks are used to build retaining walls, storage bays and segregation walls for materials such as aggregates, salt, compost, grain, woodchip, waste and recyclables. They are also suitable for temporary works, fire-resistant walls and above-ground fencing or hoarding systems.
Are Duo™ concrete blocks a permanent or temporary solution?
Duo™ blocks are generally classed as a temporary or semi-permanent structure because they are dry-laid and can be dismantled and relocated. This often reduces planning requirements and can lead to lower business rates, though local authority guidance should always be checked.
Do Duo™ interlocking blocks require foundations?
In most cases, no traditional foundations are required. Duo™ blocks can be dry laid onto any firm, level surface with adequate ground bearing capacity. Ground conditions should always be assessed before installation.
Is planning permission required for Duo™ block walls?
Many Duo™ block structures do not require planning permission, particularly when used as temporary storage bays. However, planning rules vary, so it is recommended to confirm with your local planning authority before construction.
How high can Duo™ block walls be built?
Maximum wall height depends on block configuration, stored material type and density, ground conditions, and wind loading (for freestanding walls). Guidance is available in the Stability & Loading Calculations Directory. A structural engineer should be consulted for taller or higher-risk walls.
Are Duo™ interlocking concrete blocks fire resistant?
Yes. Duo™ blocks are manufactured from precast concrete, which is non-combustible and provides excellent fire resistance, making them suitable for waste, recycling and industrial environments.
Can Duo™ blocks be reused or relocated?
Yes. Duo™ blocks are designed to be fully reusable. They can be dismantled, reconfigured and relocated without specialist lifting equipment, making them a cost-effective long-term solution.
What sizes do Duo™ concrete blocks come in?
The Duo™ range includes three modular sizes: 600 × 600 × 450 mm, 1200 × 600 × 450 mm, and 1800 × 600 × 450 mm. This allows flexible wall and bay design to suit different site layouts.
How much do Duo™ interlocking blocks weigh?
Weights vary by size: Small block: 375 kg; Standard block: 750 kg; Large block: 1125 kg. Exact weights are provided in the technical specifications.
Are Duo™ blocks compliant with UK standards?
Yes. Duo™ interlocking concrete blocks comply with BS EN 1992-1-1:2004 – Design of Concrete Structures and are manufactured in the UK by Elite Precast Concrete.
Can Duo™ block walls retain loose materials safely?
Yes, when designed correctly. Walls should be built on a suitable base and materials should be allowed to naturally form against the wall. Loading guidance is available, but structural advice should be sought where required.
Do Duo™ blocks need mortar or fixings?
No. Duo™ blocks are dry-laid. Their interlocking connector system provides stability without mortar, adhesives or mechanical fixings.
Can Duo™ blocks be used outdoors?
Yes. Duo™ blocks are designed for external use and perform well in harsh environments, including exposure to weather, freeze–thaw cycles and heavy-duty industrial use.
What finish do Duo™ concrete blocks have?
The finish is classed as basic under the National Structural Concrete Specification. Decorative finishes are available separately.
What safety checks are required before installation or reuse?
Before lifting or reusing blocks: inspect lifting pins for wear or corrosion; check blocks for cracks or damage; avoid impact from mobile plant during use. Damaged blocks should not be lifted or installed.
Can Elite Precast Concrete provide design support?
Yes. Elite Precast Concrete offers design and installation guidance, stability and loading advice, and structural and foundation design reviews on request.
Who is responsible for structural checks?
It is the customer's responsibility to ensure appropriate structural and ground checks are completed before installing any precast concrete products.
What are Duo Bay Walls used for?
Duo Bay Walls are precast concrete walls used to form storage bays for silage, grain, feed, aggregates and other bulk materials.
Are Duo Bay Walls suitable for heavy agricultural use?
Yes. They are designed to withstand heavy loading, machinery impact and demanding farm environments.
Can Duo Bay Walls be arranged in different configurations?
Yes. Their modular design allows flexible layouts to suit different yard sizes and storage requirements.
Are Duo Bay Walls manufactured in the UK?
Yes. All Elite Precast Duo Bay Walls are manufactured in the UK under controlled quality standards.
Related Products
UK Manufacturing & Nationwide Delivery
Every product is manufactured in the UK to recognised quality standards and delivered nationwide on a fleet built for site access. The result is shorter lead times, full control over quality, and the confidence of working with a British manufacturer.
Need Duo™ Interlocking Blocks on a project?
Request a quote or talk to our technical team.

