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Can You Put Resin Over Patio Slabs

Around the UK, millions of home and business owners are waking up to the benefits of resin surfacing for their patios, driveways, garden paths, and paved areas.

Why has this system become so popular? The answer is that resin-bound surfacing is incredibly durable, fully customisable, attractive, and relatively easy to look after. What's more, it can add value to your property!

At Guardian Resin, we have noticed a growing trend among customers choosing to replace their traditional patio slabs with a resin-bound surface, and this is the case nationwide.

One of the great features of resin-bound surfacing is that it can often be installed over an existing surface, saving you time and money. However, this doesn't always work in every case.

If you lay resin on top of some materials, your patio is highly likely to shift and crack, which ruins its appearance, creates trip hazards, and wastes your investment.

Today, we're asking: can you lay resin-bound surfacing over paving slabs? And we'll fully explore this topic to answer as many questions as possible, starting with the basics.

What Is A Resin Surface?

Essentially, it is resin-bound gravel - a mixture of polyurethane resin and loose aggregate that sets hard, forming an extremely tough but flexible shell.

However, you can also have resin-bonded gravel, and it's important to know the difference between these two! For more information, we recommend checking out our post titled "Is Resin A Good Choice For Patios".

Resin-Bound Or Resin-Bonded?

Despite the similar sounding names, these are two completely different systems.

With a resin-bound system, the aggregate (gravel) is mixed into the resin and trowelled into place to form a hard but permeable surface. Each stone is entirely covered with resin and is never exposed.

When laying a resin-bonded surface, the resin layer is installed first, and fine aggregate is scattered over the top, where it is exposed to the elements. These types of surfaces are not permeable and therefore sometimes require planning permission.

The Importance Of A Good Base

The key to the success of either system is that the sub-base has to be right, or the resin surface will fail and become irreparably damaged.

So, what about our main question? Can you put a resin surface over patio slabs? The following section answers this in full, along with a list of the materials that should never be used as a base for resin-bound surfaces (or resin-bonded, for that matter!).

Which Materials Are Not Suitable Bases For Resin?

To provide a stable base, you need a material that isn't going to shift or become uneven, and this rules out the following:

  • Paving slabs
  • Block paving
  • Crazy paving
  • Flagstones
  • Bricks
  • MOT type 1 aggregate (crushed aggregate used as a base for roads and footpaths. The number refers to different aggregate sizes)

As you can see, this rules out paving slabs!

But why isn't it a good idea to lay resin over these materials?

The trouble with all of the above examples is that they aren't solid. These are known as elemental pavements, as they are laid in discrete units with joints between each one.

There's a very good chance that the individual components will move independently, causing an uneven base. And any base movement affects the resin-bound surface above, potentially causing what's known as reflective cracking.

This happens when the joint between two separate paving units (like block pavers) opens, creating cracks or fissures in the covering material.

Which Materials Make A Suitable Base For Resin Patios?

Preferred bases vary depending on the resin-based system, but on the whole, the following materials are best:

  • Tarmac
  • Asphalt
  • Concrete
  • Eco-grid systems

All of these are known as monolithic materials, as they form a continuous, solid base without any joints. This should support resin-bound aggregates without shifting and causing the surface to crack.

Even though these are the best bases on which to lay resin-bound paving, there are guidelines to follow. You can also check out our post on how long do resin patios last.


Don't be fooled by those who claim that the base doesn't have to be 'perfect'! The experts at Guardian Resin see this as an excuse for poor workmanship.

Proper preparation of the sub-base, whether it's concrete or any other monolithic material, is essential for the success of your resin-bound surface.

Here are some tips on the best practice for sub-bases:

Tarmac Base

For tarmac, the existing base has to be at an adequate depth to take the extra material. The surface has to be completely clean, free from weeds, and in good condition.

If it's a newly laid base, you'll need to wait an appropriate length of time before laying the resin.

The same rules apply when using asphalt.

Concrete Base

The concrete surface has to be clean and free from damage. A polymer primer is applied to create a firm bond between the two surfaces. Without this, your resin-bound installation is likely to fail as the surfaces won't stick together.

A resin-bound system should also never be laid directly over expansion joints on concrete slabs, as this is highly likely to cause reflective cracking.

Grid Systems

Eco-grid systems require more resin-bound supplies than the other systems - usually twice the quantity, making them a more expensive option.

Even so, these are an excellent alternative to the other base materials, as they are made from recycled materials. They are also permeable and have a load-bearing capacity of up to 800 tonnes per square metre!

They are often used as a base for resin driveways because of their ability to handle heavier loads, particularly when there's no existing driveway material on which to lay the resin-bound surfacing.

A Note On Permeable Paving

Under the government's SuDS scheme (Sustainable Urban Drainage Systems), planning permission is required for certain hardscapes, like a new driveway or patio area. New developments over the past few decades have caused localised flooding as trees and natural soil have been replaced with vast sheets of tarmac and concrete. Rainwater flows directly off of these and into the drainage systems in such large volumes that they can't cope, leading to local flooding. For more learnings, you can also check out our article "Are Resin Driveways Permeable".

A Potential Solution

As mentioned above, resin-bound surfaces are permeable, allowing rainwater to soak away naturally, whereas bonded resin surfaces are not.

However, a resin-bound surface must have a porous base to qualify as permeable paving. Tarmac, porous asphalt, and grid systems are fine, whereas concrete slabs are not. You need to be aware of this and ensure that your new patio area doesn't fall foul of local authority rules!

Summing Up

So, the answer to our question is no, it's not a good idea to lay a resin system over paving slabs. While it could be said that this relates more to a resin driveway (due to the increased chance of reflective cracking because of the extra weight of cars and other vehicles) it still applies to patios.

For the best results, and to ensure that your patio stays in great condition for many years, the sub-base has to be prepared or installed correctly, and it must be made from an appropriate material, as set out in the article above.

If your existing pavement is made of flagstones or block paving, these will need to be lifted and replaced with a suitable base material.

Hopefully, this has not only answered your questions, but we have also given you a few alternatives. At Guardian Resin, customer service matters to us greatly, which is why we like to offer advice and support.

If you need further information about installing a new resin driveway, patio, or garden path, or you want to discuss any of the points raised in this article, don't hesitate - call us today, and we'll do our very best to help.

Contact Guardian Resin today at 0800 086 2857

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