Wetpour Sub Base Specifications

Wetpour rubber surfacing is extremely popular for children’s play areas throughout the UK. It is made up of a two-tier system consisting of an SBR shockpad and a coloured EPDM wearing course. As specialist contractors of wetpour, we are able to install this flooring type onto a number of wetpour sub base specifications.

It is important to correctly prepare the ground before the safety surface is put down to ensure a strong and durable finish. Without the right groundworks, there are risks of the surfacing breaking up, being unstable and requiring wet pour repairs in the future.

Please get in touch with us through our contact form if you would like to install one of these playground safety surfaces. We have worked with many schools and nurseries and would be happy to provide a quote for you.

Suitable Bases for Wetpour

The best types of base for this rubber play flooring are smooth, permeable, strong surfaces. This is important as we need to make sure that the school playground flooring will be strong and safe for use by children every day. Here are some common specifications that we can lay wetpour onto.

Porous Stone Base

One of the most commonly used wetpour sub base specifications in a playground is a porous stone surface. This is made up of lots of loose stones which, when compacted, provide a stable and permeable finish. The porosity means that water will drain through it and into the ground, reducing any risk of flooding on the play area.

Laying this type of foundation for a playground surface will typically use this process:

Excavate the ground to a 125mm depth, plus the depth of wetpour to lay (minimum 40mm).
Install PCC edgings across each side of the area.
Lay and compact the layer of stones to a depth of 125mm.

We can then lay the rubber playground surfacing directly onto this. Many clients will choose to install the groundworks in this way as it is the most simple and cost effective method.

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Open Textured Macadam

Macadam (or tarmac) is a hard and durable material which provides a great foundation for wet pour play surfaces. It is porous which means any water that drains through the playground flooring itself will then drain through the base and into the ground below. This helps to prevent water from sitting on the surface and causing flooding to the area.

The process of installing the rubber surfacing with a porous open textured macadam sub base would be as follows:

Excavate the existing ground to a depth of 150mm, plus the depth of wetpour surfacing which we will lay.
Lay PCC edges along each side of your chosen area.
Install and compact permeable stone to a depth of 100mm.
Install and screed 50mm of open textured macadam.

Once this is complete and the tarmac has been left to cure fully, our team can lay the chosen wetpour system on top. Whilst the option of a macadam foundation does provide the most durable finish, it is not always cost-effective for every project.

It also requires extra time to cure before our team can install the playground surface itself. If you need to reduce the costs and duration of your project, we’d recommend the porous stone sub base as this still provides a suitable foundation.

No Fines Concrete

We can install rubber play surfacing onto a permeable concrete specification. This usually consists of limestone chippings mixed with neat cement and water. Due to this base surface being ‘no fines’ it also offers porosity as it doesn’t contain any smaller pieces of stone which could block up the air holes. Therefore water is able to soak through it and pass through to the ground, meaning the play surface won’t flood.

We will generally install the permeable concrete using this method:

Excavate the current surface down to a 175mm depth, along with the chosen depth of wet pour surface.
Put PCC edges around the perimeter of the space.
Lay and compact 100mm of porous stone.
Lay and screed 75mm of no fines concrete.

Once this foundation sets and cures, we can lay the wetpour rubber flooring onto it. This leaves a strong and level finish for a safe playground facility.

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Each of these three wetpour sub base specifications offers the right performance and safety qualities to support a playground surface. If the existing area is already porous tarmac or concrete, it is likely that we will be able to lay a wet pour system directly onto this. However, it will depend entirely on the condition on the surfacing.

Please note that the depth between the top of the edgings and the top of the base system should be no greater than the depth of the wetpour we’ll lay. This is to create a smooth and level finish for the play area surface, and to make sure that the rubber flooring meets the correct Critical Fall Height ratings.

This video below shows the full installation of a playground using wet pour graphics and a colourful design. The rubber flooring provides safety for children using the different pieces of equipment on this facility.

Unsuitable Bases for Wetpour

There are a number of surface types that we would not be able to install the wetpour playground system onto. These include:

Non-Porous Concrete or Tarmac – Due to the specification of wetpour being permeable, a non porous concrete or tarmac surface would not be an acceptable foundation. This is because any rainwater not be able to pass into the ground below. It would therefore sit within the layer of rubber and weaken it. As well as this it could potentially cause flooding to the play area.
Grass – An existing grass area would not provide the right stability as a base for wetpour. There is also the risk that grass and weeds could start to grow up through the playground surfacing if we lay it onto grass.
Mud – A muddy surface wouldn’t be strong enough to safely support a wet pour rubber system. However, an alternative safety surface which can be put onto mud or grass is rubber mulch and we can install this as well.

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When we are installing the EPDM rubber flooring for a play area, it’s vitally important to have a suitable sub base put down beforehand. This helps to ensure the strength and durability of the play area, making certain that it lasts a long time and is safe for children to use on a daily basis.

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If you need any further information about the various wetpour sub base specifications that we can use, please feel free to contact us today. We also offer advice on prices and designs for your playground surface. So simply fill in the contact box on this page to get in touch with our friendly team.

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