Will Interlocking Concrete Block Hold Water?

What do You Put Under Retaining Wall Blocks?

With many types of building solutions on the market, it could be difficult to know what option would suit your needs, whether you are building temporary storage or a retaining wall. In this blog we at PPC Concrete Products will be answering the question, ‘What do you put under retaining wall blocks?’

Retaining walls are vital in order to organise land in order for development or to make it safer in a populated area, some people opt to use wood, or brick & mortar for their retaining walls whilst we present an alternative option in our interlocking concrete blocks.

With the necessity of time and cost-efficient building solutions being needed, as construction output in Great Britain has seen an increase, alternatives to traditional brick-and-mortar builds are required for those looking to save time and money, whether that’s building temporary structures, a retaining wall and everything else in between. 

But first, let us explain a little bit more about retaining walls.

Retaining walls

A retaining wall is a structure designed to restrain land to a slope it would not naturally keep to. For example, a retaining wall could be built in order to organise a road by a small hill. Retaining walls are a way to organise land without having to totally alter the landscape.

The benefit of a retaining wall ranges from aesthetics to creating more space, to ensuring safety on a piece of land, generally with any building of a retaining wall, these three benefits should be the standard result you are left with.

What is used to make a retaining wall?

A retaining wall can be made of wood, cement, Gabion baskets & our interlocking concrete blocks. Each method has its advantages, but this is all subject to the needs and allowance of the project in question.

Our Interlocking concrete blocks present an easy, and efficient method of setting up a retaining wall. If you want a simple and efficient method, Interlocking concrete blocks is the way to go. You do not need to fill a retaining wall when using our interlocking concrete blocks. Below, we explain the building of a retaining wall using our blocks.

How to build a retaining wall with interlocking concrete blocks

The first factor before building an interlocking retaining wall is determining the depth of the foundations otherwise known as the footings. If the soil is firm and well-drained, 300mm should be enough. Alternatively, if the soil is not as firm and unstable, 450mm would be suitable. (This will vary depending on the need for the foundation, size, project etc).

After the foundation has been measured, made and set, placement of the concrete blocks can take place to the desired height.

As there is no need for mortar or any binding facilitation, interlocking the blocks via stacking so their studs and recesses connect will be more than enough to guarantee a stable structure.

We understand retaining walls can come in different lengths, shapes sizes and for clients who have different needs. So to show you our abilities and expertise, we have a review for you to read that highlights and reviews a job we did for JO Transport.

Still not convinced with the effectiveness of our Interlocking concrete blocks? If so, here is a breakdown of our blocks to help you understand just how amazing they are.

What do you put under retaining wall blocks?

When it comes to creating a retaining wall with our interlocking concrete blocks, you generally don’t need to treat the floor before placing the blocks (this will obviously vary in accordance with the project.)

If you have any concerns about a project in which you’d like to use our blocks, please contact us so we can give you the best advice for your project.

Do retaining wall blocks need mortar?

Our interlocking concrete blocks do not need mortar to connect, they connect by aligning the studs and recesses and allowing them to ‘click’ into place. This saves you time, manpower, and equipment you’d normally use for a brick-and-mortar build.

Once our interlocking concrete blocks connect, they don’t have to be like that forever, if needs be, you can disconnect & reconnect the blocks without any reduction in their overall function.

Additional information on Interlocking concrete blocks

As building regulations came into being in England, the requirements of having fire proof dwellings was compulsory, this was achieved by subsequent houses being made of stone and brick. Interlocking concrete blocks present a modern alternative.

Interlocking concrete blocks are a unique form of pre-cast concrete blocks that are designed to hold together by using pre-measured studs and recesses. Built with unique profiles and features, which allow them to fit perfectly into each other without the use of any mortar. Instead, the cementitious blocks simply snap together with each other.

Depending on the size of the block that is chosen will affect the number of studs that are on the block. In regards to the sizing, interlocking concrete blocks don’t need mortar to be held in place. This means the speed of building is improved, whilst using less manpower.

Other concrete providers may offer “concrete lego blocks” the differences between the two aside from their names are nominal. The functionality is the same, and the only variants will be the sizes, amount of studs/recesses or styles, such as the ‘rock face’ option we offer. Other suppliers may offer alternative styles and sizes than us and as a result, you may be paying a premium price for it.

The advantages of interlocking concrete blocks

  • Longer lasting and more durable than a Gabion basket
  • Quicker and less hassle to install
  • No need for mortar, saving you money and time
  • No need for steel reinforcement or shuttering
  • Resistant to extreme weather conditions
  • Fire-resistant properties, mitigating the spread of fire depending on structure
  • Little maintenance required
  • Often, no foundation is needed before installing
  • Sound resistant
  • Sustainable
  • Ability to stack them upon each other
  • Flexibility in sizes
  • Appropriate for temporary and/or permanent buildings
  • Unlikely to be displaced due to the interlocking function
  • Can be moved with standard lifting equipment

What are interlocking concrete blocks used for?

As we at PPC Concrete products supply interlocking concrete blocks, we can share with you what they are used for.

  • Material Storage bays
  • Blast walls
  • Salt stores
  • Crash protection
  • Flood protection
  • Push walls
  • Security barriers
  • Segregation bays i.e recycling centres
  • Retaining walls
  • Industrial buildings
  • Fire breaks
  • Counterweights
  • Roadblocks

And much more.

How much does a retaining wall block cost?

For anybody wondering how much are interlocking concrete blocks, there is no set price for Interlocking concrete blocks because it will depend entirely on your project, preference, size, and quantity you need. Along with this, offloading and installation are available via a third party. This is why we strongly encourage you to contact us on our website to get your quote.

Can I just use wood?

Yes, you can use wood to create a retaining wall, as long as it is suitable for your needs, but here are some things to consider before buying all of the tools and equipment you need.

In terms of using wood,  in the short term, the cost is completely dependent on the scale of the project. But manpower, equipment & supplies will be factors to consider, so this means you might be spending more money by having a wood retaining wall as opposed to using our retaining wall blocks.

That being said, in the long term, our interlocking concrete blocks provide a heavy load-bearing option that is also more resistant to weather conditions than wood. Even with protection, wood can degrade over time especially outside being exposed to seasonal weather changes.

The likelihood of having to repair or refit a wood retaining wall is slightly higher, so on this basis, we would say that generally, a concrete retaining wall is cheaper than wood, especially if we consider the possible long-term costs.

Contact us today

As an established supplier all over the UK, PPC Concrete Products is always happy to help, which is why we encourage you to get in touch with any questions you may have or take a look at our FAQ.

In this article, we hope to have answered the question ‘What do you put under retaining wall blocks?’ Whilst also providing extra information in regard to construction and the benefits of interlocking concrete blocks.

Take a read of our case studies to truly understand how we have provided solutions for business in the past with the use of our interlocking concrete blocks, and ultimately, how we can help you today.

Read our blog page for more insights into our passion, construction.


The Old Gasworks,

Higginshaw Lane,




Share on Facebook Share on Twitter Share on Google