Do Retaining Walls Need Drainage

Do Retaining Walls Need Drainage

It can be argued that retaining walls are a necessity in most modern settings. But they aren’t easy to make. Every retaining wall must be made with consideration to the area surrounding it and the building regulations that are relevant to it.

But is that all there is to it? Or are there extra considerations in place that must always be in the forefront of a builder’s mind when constructing a retaining wall? Considerations like drainage?

In this blog, we will answer the question ‘Do retaining walls need drainage?’

At PPC Concrete Products, we are here to provide solutions for your construction needs,

from the person working their own part-time project, to commercial clients, and everyone in-between.

Monthly construction output had risen an estimated by an 1.6% value in June 2023, and we would like to think our accessible concrete products had a small part to play by giving our clients easy access to reliable and easy-to-use construction solutions.

Retaining walls explained

Retaining walls explained

Retaining walls are versatile structures that are used within landscaping in a vast majority of settings. The primary function of a retaining wall is to hold back soil that would naturally slope or crumble. Here are some of the benefits of a retaining wall.

  • Retaining walls helps to prevent erosion. Without one, rainwater can wash soil away from slopes, particularly hills, overtime. A retaining wall acts as a barrier, keeping its area intact.
  • A natural slope can sometimes create issues in space management, whether it’s your garden or public/private land. A retaining wall reimagines this space into a flat, useable area. This newfound space can be utilised for many other uses.
  • A retaining wall helps you to optimise uneven terrain in different ways, for example, you can optimise a retaining wall so it has a tiered aesthetic.
  • Aesthetically, retaining walls, when done right, create a distinctly organised look for any space. Their practicality and aesthetic benefits go hand in hand.
  • A retaining wall with proper drainage can help to protect the area it is located in from flooding.

Do retaining walls need drainage?

Do retaining walls need drainage?

Yes. Retaining walls absolutely require drainage to ensure functionality and longevity. But how exactly is drainage incorporated into a retaining wall? Below, we will list common elements for drainage in a retaining wall.

  1. Drainage Stone: This is the most common element. Crushed rock or gravel is placed against the backfill (soil) area behind the wall. The gaps between the stones allow water to drain freely away from the wall. Drainage stones should typically extend at least 1 foot (30 cm) away from the wall and up to near the top of the wall, leaving a few inches of space at the very top.
  2. Filter Fabric: This is a special fabric placed on top of the drainage stone. It allows water to pass through while preventing soil particles from clogging the drainage system.
  3. Weep Holes: These are small openings constructed at the bottom course (row) of the retaining wall blocks. They allow water that has seeped through the backfill and drainage stone to escape and drain away from the wall. Weep holes should be spaced evenly across the length of the wall.
  4. Drainage Pipe (Optional): In some cases, depending on factors like wall height, soil type, and rainfall, a perforated drainage pipe might be installed behind the drainage stone. This pipe collects water and directs it to a drain outlet away from the wall. The perforated holes allow water to enter the pipe, while the solid pipe structure prevents soil from entering and clogging it.

What happens if a retaining wall has no drainage?

There are multiple issues that can arise if your retaining wall has no drainage capabilities, even if it does have drainage, but is poorly incorporated, it can result in a few issues such as…

  • Puddles at the surfaces of your retaining wall. Because the water from rain etc can not travel through the drainage of your retaining wall, it will collect and pool, the most severe cases will result in puddles at the top of the retaining wall.
  • The retaining wall can bend. This happens as a result of the additional weight that the undrained water creates. Due to the unforeseen excess pressure on the retaining wall, it has the capacity to buckle under the weight, damaging it permanently.
  • For similar reasons to the bending of a retaining wall, it can also bulge in certain areas. This is due to the additional weight from the water affecting weaker areas of the retaining wall structure.
  • The moisture may find another area to escape from, which can become a hindrance or a health hazard, depending on the area.
  • Depending on the location of your retaining wall, the undrained moisture can travel to other areas, which can cause negative consequences such as leaks etc.

How do I make sure my retaining wall has drainage?

The most simple and effective way of ensuring your retaining wall not only has drainage, but the appropriate drainage for your specific retaining wall, is by using the services of an expert.

By using an established, expert service to create your retaining wall, you are preventing any guesswork that would be used when creating a retaining wall by yourself, or with an unestablished builder.

What can I use to make a retaining wall?

What can I use to make a retaining wall?

One of the most effective resources you can use when it comes to creating a retaining wall are Interlocking Concrete Blocks. These special pre-cast blocks do not require mortar in order to create a long-lasting and effective connection.

Interlocking Concrete Blocks connect to each other via studs and recesses at the top and bottom of the blocks, respectively. Individually, concrete blocks are heavy, but once they are joined, they provide an excellent counterweight against exceedingly heavy applications like a retaining wall.

Considering the fact they do not require mortar to connect, it is safe to say you will be saving money that would otherwise be spent on binding materials, and even some labour costs. But what actually makes Interlocking Concrete Blocks special? Well, a lot of things.

Here is a list of some of the uses that Interlocking Concrete Blocks can facilitate.

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

What are 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 the 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

Create a retaining wall 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 have a look at our FAQ.

In this blog, we hope to have provided guidance by answering the question ‘Do retaining walls need drainage?’ Whilst also providing additional information including construction solutions that we offer.

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.


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Higginshaw Lane,




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Tel: 01706 655245


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