Duo™ Interlocking Blocks

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.

What are Duo™ Interlocking Blocks?

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

  • BL1Dimensions (mm): 600 x 600 x 450 mmWeight (kg): 375 kg
  • BL1 (F)Dimensions (mm): 600 x 600 x 450 mmWeight (kg): 375 kg
  • BL2Dimensions (mm): 1200 x 600 x 450 mmWeight (kg): 750 kg
  • BL2 (F)Dimensions (mm): 1200 x 600 x 450 mmWeight (kg): 750 kg
  • BL3Dimensions (mm): 1800 x 600 x 450 mmWeight (kg): 1125 kg
  • BL3 (F)Dimensions (mm): 1800 x 600 x 450 mmWeight (kg): 1125 kg

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.

Installation Overview

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

Typical Loading Guidance

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

Compliance & Technical Support

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.

Safety & Responsibility

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

Applications

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.

Finish & Appearance

Gallery

Important downloads

  • Duo block 2.7m high 0.8t per m³ calcs
    PDF750 KB
  • 572 03 Duoblock Design Summary
    PDF624 KB
  • Duo block 1.8m high various materials calcs
    PDF457 KB
  • Duo 2.7m Typical Foundation Detail
    PDF364 KB
  • Duo Blocks 4.05 high Load Case 1 Design Summary
    PDF480 KB
  • Duo block – Storing baled paper cardboard – essential guidance
    PDF300 KB
  • Duo blocks 4.05m high indoor single skin wall – 0.6 tonnes per m3 calculations
    PDF466 KB
  • EPC TYP 005 Aggregate Bays 20kN m3 x 2.25m Duo
    PDF1.2 MB
  • Duo 2.7m retaining wall
    PDF99 KB
  • Duo Bay Typical Loads
    PDF1.5 MB
  • Duo block 3.15m high 1.0t per m³ calcs
    PDF752 KB
  • Duo Blocks earth retaining 1.8m high Design Summary
    PDF298 KB
  • Duo blocks 4.05m high indoor single skin wall – 0.34tonnes per m3 calculations
    PDF464 KB
  • Duo block 0.9m high 0.8t per m3 calcs
    PDF740 KB
  • Duo Blocks 4.05 high Load Case 2 Design Summary
    PDF477 KB
  • EPC TYP 002 Fire Wall 3.15m Duo
    PDF397 KB
  • Impact Load Calculation Summary 2.7 Duo Blocks
    PDF156 KB
  • Typical loads Duo Legato and Vee
    PDF4.9 MB
  • EPC TYP 004 Storage Bays 18kN m3 x 1.8m Duo
    PDF911 KB
  • Duo block 2.25m high 0.8t per m³ calcs
    PDF757 KB
  • Duo Blocks earth retaining 2.25m high Design Summary
    PDF290 KB
  • Shear Force Legato Duo Blocks
    PDF94 KB
  • Duo block earth retaining 0.9m High Calculation Summary
    PDF347 KB
  • Duo blocks – 1.8m high Bund wall calculations
    PDF378 KB
  • 9 Block High Duo Black Bag Waste Single skin Calculation Summary
    PDF253 KB
  • Duo 2.7m High Load Diagram amended notes
    PDF301 KB
  • Duo block 3.15m high dry loam 1.3 tonnes per m3
    PDF254 KB
  • EPC TYP 003 Shredded Bales Storage Bay 19.2m x 3.15m Duo
    PDF699 KB
  • Duo block 3.15m high 0.34t per m³ calcs
    PDF393 KB

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.

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