The ultimate permeable concrete system

Topmix Permeable is a fast draining concrete pavement solution that rapidly directs stormwater off streets, parking surfaces, driveways and walkways. This minimises the cost and long-term maintenance for local authorities and developers of stormwater management.




  1. Efficient stormwater management

  2. Environmental management

  3. Reduced costs

  4. Ease of placement

  5. Aesthetic appeal


  • Sports pitches
  • Sub-base
  • Cycle paths
  • Parking lots
  • Driveways
  • Side walks


Topmix Permeable Next High Wycombe

Planning requirements for this large retail development dictated that a sustainable drainage solution was required in the form of a permeable pavement for the 2800 m2 parking area.


Topmix Permeable Lindum Homes

Lindum Homes were developing a 20 housed small residential estate. They wanted a permeable surface pavement and car parking area for residents.


Topmix Permeable Roots Farm Shop

Roots Farm Shop wanted to extend their car parking facilities due to customer demand. Our permeable concrete offered a full attenuation system with the ability to increase the hard standing area whilst maintaining the pre-existing infiltration rates.


Topmix Permeable Worksop Golf Course

Worksop Golf Club required an overspill car park to cope with increasing customer demand.


Topmix Permeable Biggleswade Retail Park

A pavement for a car park was required that would be durable, free draining and comply with the water management requirements of the planning approval.


Topmix Permeable A628 Cockerhill Retaining Wall

When Tarmac were approached to provide a lightweight material that could also direct water away from a retaining wall, Topmix Permeable was the ideal solution.


Won’t the pavement crack when freezing temperatures are reached?

A permeable design encompasses not just a structural design but also a hydraulic one. This design would be based on many factors such as the design storm event ground permeability and total area to be drained from. This would then normally determine the required thickness of the attenuation layer. (This is basically a storage layer made up of an aggregate with 30-40% voids). It is in this layer that the water would sit, not within the structure of the permeable surface layer so if the water was to freeze it would not have any detrimental effect on this.

Won’t the pavement become blocked by dirt and therefore not work after a while?

Topmix Permeable has an average permeability rate of 36,000mm/hr. The minimum required permeability rates will vary greatly according to local climate conditions, but as an approximate guide, the average permeability required to cope with a 100-year storm event is 300mm/hr. As the permeability rate of this material is so great, there would have to be an unrealistic amount of dirt applied to the surface for the pavement to cease functioning effectively. It is recommended that permeable paving must still be able to function effectively when blocked by up to 95%.

We wouldn’t recommend that Topmix Permeable is used in areas which are going to be used for activities such as stockpiling sawdust or in areas where there will be heavy silt loads eg large recycling centres but is suitable for most other applications.

Will this material be susceptible to sinkholes?

Sinkholes are usually the result of what are known as Karst processes. They happen when a layer of rock underneath the ground is dissolved by acidic water. Before any SuDS design is implemented on a site, a ground investigation report will be carried out. This will highlight any potential issues with the ground conditions that might lead to problems so that they can be rectified before the SuDS system and permeable pavement are installed.


  • Achillies Building Confidence
  • Carbon Trust Standard
  • Kitemark Readymix 2

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