Flooding is a common issue in many parts of the UK, whether it is from coastal flooding, river flooding, or flash floods. This means that understanding how to protect properties and structures is crucial, and being able to implement the correct measures is a must, which begs the question—is it suitable to use concrete blocks for flood defence?
Concrete blocks—especially interlocking concrete blocks—can be used for flood defence, and are an excellent choice for doing so. Concrete in general is a good material for creating flood barriers, but the type of concrete, coatings, and its density plays a key role in its effectiveness and reinforcement.
To find out more about concrete blocks at PPC Concrete Products, why not check out our blogs about installing interlocking concrete blocks, benefits of concrete blocks in waste management, if they can be used for temporary structures, and how these blocks stay in place.
Why Do Flood Defence Structures Matter in the UK?
Flood defence structures matter in the UK because of the amount of flooding that the UK experiences. Being able to properly prepare for floods and prevent them from causing damage to crucial infrastructure while also finding solutions that last, are eco-friendly, and are effective, is key—and it is why using concrete blocks for flood defence is the perfect answer.
Parts of the UK most prone to flooding:
- Somerset (river flooding)
- Essex (river flooding)
- Norfolk (river flooding)
- Cumbria (flash floods)
- Lincolnshire (flash floods)
- Yorkshire (flash floods)
- Cornwall (tidal flooding)
- Hull (tidal flooding)
- Great Yarmouth (tidal flooding)
- Sussex (tidal flooding)
- Kent (tidal flooding)
Can Concrete Blocks Be Used for Flood Protection?
Concrete blocks can absolutely be used for flood protection, and, in fact, should be. Thanks to the durability and water resistance, using concrete blocks for flood defence is an easy and effective choice for a common problem that many of us in the UK face.
Both concrete and reinforced concrete are the best materials for building flood barriers, particularly when building permanent barriers. For barriers that will only be needed short-term, and for areas where flooding is rare, tightly stitched sandbags are a reasonable option.
How Effective are Concrete Blocks for Flood Protection?
Concrete blocks are highly effective for flood protection, with interlocking blocks being able to not only withstand floodwater pressure, but also having the ability to create long-lasting structures while eliminating the need for mortar and saving money and time.
The density of the concrete blocks plays a key role in how effective they are at flood protection as well. High-density blocks (typically with a density between 1,800 to 2,100 kg/m³) are heavier, less porous, and more suitable for stopping the devastation of floods, while lightweight blocks (with a typical density between 650 and 1,200 kg/m³), are more porous, weigh less, and are not the ideal option for flood protection.
What are the Benefits of Using Concrete Blocks in Flood Defence Projects?
There are numerous benefits of using concrete blocks for flood defence, including their strength and durability, water resistance properties, rapid deployment for interlocking blocks, and the modular designs of these blocks that allow for greater flexibility.
Strength and Durability
The durability and strength of concrete blocks ensure that any flood defence that is put up will last and remain intact, even after consistent and harsh flooding. This is especially the case for high-density blocks, which are made to be water-resistant and remain in place.
Water Resistance
Although you can and should apply a water-resistant coating to your concrete blocks, high-density blocks have the benefit of already being resistant to moisture due to the compressive strength and overall density. This ensures that water will not seep through the bocks over time, allowing the defence to work as intended.
Rapid Deployment
The rapid deployment of concrete blocks for flood defence is unparalleled, particularly for interlocking blocks that do not require additional materials like cement to be put together in order for the structure to be effective. All you need to do with these interlocking blocks is correctly put them in place, and they will be effective against flooding.
Modular Design for Flexibility
Interlocking concrete blocks are incredible for their varying modular designs and flexibility. There are many different types of interlocking blocks, with different designs and sizes being suitable for different projects, areas, and uses depending on your needs. These blocks ensure stability from the get-go, and once they are properly placed, will offer long-lasting protection against floods while also saving money by not requiring mortar.
Which Types of Concrete Blocks are Best for Flood Barriers?
Interlocking or modular concrete blocks are the best option for flood barriers for a number of reasons. These blocks are great for flood defence as well as fire resistance, and can be used in a number of ways, including for retaining walls and defence on both residential and commercial properties.
Benefits of using interlocking or modular concrete blocks for flood defence:
- Incredibly strong and durable
- Can be rapidly deployed for emergencies
- Fantastic customisation potential
- Fewer resources like mortar are required
Block Density and Water Resistance
The denser a block is, the more water-resistant it is, and therefore the better it is for flood prevention. High-density concrete blocks are the perfect option for water-related construction and defence, but do come with the added difficulty of difficulties with handling due to their weight.
Generally, the minimum density deemed to offer good water resistance is 1,500 kg/m³, and a compressive strength of at least 7.3N/mm2 to provide enough resistance to moisture. As such, opting for blocks with higher density and compressive strength will give better results and last longer.
Which Blocks are Not Suitable for Flood Defence?
Lightweight blocks are generally considered to not be suitable for flood defence due to their weight and density. As these blocks are usually made from pumice, ash, or expanded clay mixed with cement, water, and sand, they are porous and prone to structural issues if they are exposed to excessive moisture. While they can be coated with water-resistant finishes, it is safer to avoid using lightweight and some medium-density blocks for this purpose.
Real-World Applications and Use Cases of Concrete Block Flood Defence
A recent example we have seen of concrete blocks for flood defence is that of Swanage, where blocks are being used for key sea flood defence after storm Ciaran in 2023. These blocks are currently only temporary, with a more permanent plan being implemented in winter 2025, but the blocks in place are doing their job now that they have been better positioned along the seafront.
Concrete blocks have also been used as part of flood defence in Bewdley, Worcestershire, and more notably in Redcar, where pre-cast concrete blocks weighing up to 28 tonnes each were slotted into place along the 2.7km along the coast.
Concrete block flood defence is growing in popularity, with interlocking blocks becoming increasingly widespread to prevent coastal, river, and flash flooding around the country and in many other parts of the world.
Why Choose PPC Concrete Products for Flood Defence Solutions?
Flooding happens frequently in the UK, with many parts of the country being more susceptible to it than others. However, with the right projections in place and using concrete blocks for flood defence where needed, the damage that we have seen could be a problem of the past.
Looking for reliable concrete blocks for flood protection? Contact PPC Concrete Products to discuss durable, UK-ready solutions for your flood defence project.
Contact us on 01706 580106 or by emailing us at info@ppcconcreteproducts.co.uk, or learn more about construction through our blog with posts about how to enhance construction site security with Jersey Barriers, how interlocking concrete blocks help marine life, or if you can paint these blocks.
