Interlocking Concrete Blocks: The Go-To Solution for Custom Building Projects
Strong, flexible, and surprisingly versatile for constructing retaining walls and storage bays
When space is limited and flexibility is essential, few products are as effective as interlocking concrete blocks. Whether you’re constructing a storage bay, a retaining wall, or a modular building with a fabric cover system, these heavy-duty precast units give you strength, speed, and versatility in one package.
Often called concrete Lego blocks because of how they lock together, interlocking blocks are quick to install, can be reconfigured at any time, and are designed to withstand the harshest environments.
But what truly makes them a preferred choice for contractors, engineers, and site managers? Let’s take a closer look.
How much do interlocking concrete blocks cost?
Cost is always one of the first questions. Our Allegro® interlocking blocks start from £87.50 + VAT per unit. Prices vary depending on:
- Block size (1.5m, 1.6m, or 1.8m)
- Quantity ordered
- Delivery location
- Whether off-load is required
Because each project is unique, we’ll provide a customised quote within 24 hours. This guarantees you receive an accurate cost that reflects your site and requirements.
Tip: The 1.5m blocks maximise load capacity per vehicle, up to 22 units on a single artic, which helps keep delivery costs down for smaller projects.
How are interlocking blocks delivered and installed?
One of the biggest advantages of Allegro® interlocking concrete blocks is that they can be on-site and in use quickly.
Delivery options
- Delivered on articulated flatbed lorries or curtain-sided vehicles.
- HIAB craned vehicles available if you don’t have plant on site for offload.
- UK-wide delivery, usually within 24–48 hours for stock blocks and 2–4 weeks for larger orders.
Handling safely
Each block is cast with DEHA lifting pins in the top. Units are delivered with lifting clutches, allowing them to be moved with a telehandler, forklift, or 360 excavator.
Safety guidance includes:
- Chains or straps must be attached securely, not laid over forks.
- If two lifting points are used, chains should hang at no more than a 30° angle from vertical
- Never stand beneath or near lifted blocks during handling.
Installation services
If you’d rather leave it to us, we can provide a full installation package:
- Supply of all lifting equipment and clutches.
- Trained site team.
- Method statements and risk assessments.
- Offload, positioning, and wall build.
With the right team and equipment, you can expect up to 50 blocks to be installed in a single day, giving you instant walls with minimal disruption.
Why the 1.6m Allegro® block range is the most popular
While we supply 1.5m and 1.8m blocks, the 1.6m Allegro® system is by far the most comprehensive and widely used. Their flexibility makes the 1.6m range ideal for waste and recycling facilities, industrial storage bays, and fire or blast walls where higher and stronger walls are needed.
- Bigger and stronger – weighing 2.46 tonnes, each block offers exceptional stability.
- Seven block types – including full blocks, halves, three-quarters, spreader blocks, flat tops, and sloped ends – make it easy to design multi-bay layouts.
- Build higher walls – engineered to withstand surcharges of up to 20 kN/m², perfect for bulk material storage.
- Fire resistant – Class A1 non-combustible, with up to 120 minutes fire resistance (4 hours with sealed joints).
- Long design life – unreinforced C40 concrete ensures a 100-year design life, with no risk of steel corrosion
Other sizes in the range
- 1.5m Allegro® Blocks – slightly lighter, making them easier to handle and allowing more units per delivery load. A cost-effective option for smaller bays and temporary works.
- 1.8m Allegro® Blocks – the longest in the range. Best for low-level walls and fast installs where fewer lifts reduce installation time.
Together, these three sizes give contractors the flexibility to balance height, strength, and speed.
Interlocking Block Comparison
| Range | Size (full block) | Weight | Block types | Best for |
|---|---|---|---|---|
| 1.5m Allegro® | 1,500 × 600 × 600mm | 1,270kg | 3 | Low walls, faster handling |
| 1.6m Allegro® | 1,600 × 800 × 800mm | 2,460kg | 7 | Heavy-duty, complex layouts |
| 1.8m Allegro® | 1,800 × 600 × 600mm | 1,522kg | 4 | Long, continuous wall runs |
Typical applications of interlocking concrete blocks
Interlocking blocks are designed to be reused and reconfigured, which makes them one of the most versatile precast products on the market.
Storage bays
Used for aggregates, salt, sand, and bulk goods. Blocks interlock to form strong dividing walls that can be adapted as storage needs change.
Waste & recycling facilities
Smooth faces make them easy to pressure wash, while their weight withstands constant impact from loading shovels. Fire resistance means they’re safe for high-risk environments.
Site security
Placed across gateways or around compounds, Allegro® blocks act as vehicle barriers to prevent unauthorised access.
Retaining walls
Used in landscaping or construction, they provide modular support for sloped ground or earth retention.
Fire and blast walls
Certified A1 fire resistance makes them suitable for high-risk industrial facilities.
Flood protection
Can be quickly deployed as temporary flood defences, then dismantled once the risk has passed.
Modular buildings with fabric overs
Another growing application is combining interlocking blocks with high-tensile fabric shelter systems, such as Toro Shelters.
- Blocks form the structural base and side walls.
- A tensile fabric roof is then fixed across a lightweight steel frame.
- The result is a modular covered building that’s fast to erect, weather-resistant, and adaptable.
These systems are widely used for:
- Material storage (grain, fertiliser, feed).
- Waste and recycling facilities.
- Salt barns for highway depots.
- Industrial machine storage.
By pairing Allegro® blocks with a tensile cover, you get the strength of precast concrete with the flexibility of a relocatable, low-maintenance building.
Maintenance, repair, and reuse
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- Cleaning – jet wash surfaces to remove dirt and residues
- Repairs – small chips can be repaired with cementitious or epoxy fillers.
- Reuse – blocks can be dismantled and reused elsewhere. At the end of life, crushed blocks can be recycled as hardcore
Why choose Allegro® blocks for your project?
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- Heavy-duty C40 concrete, built for aggressive environments.
- No fixings required – stability comes from weight and nib interlock.
- Comprehensive range – 1.5m, 1.6m, and 1.8m sizes, plus specialist blocks.
- Rapid delivery and installation – 48 hours for stock, 2–4 weeks for larger orders.
- Flexible applications – from recycling bays to modular buildings.
- Long design life – 100 years with minimal maintenance.
Want to discuss a project?
We’ve supplied hundreds of projects across the UK with Allegro® interlocking blocks.
Whether you need a few units for a small wall or hundreds for a recycling facility, our team can help design, deliver, and install the right solution.
