Permavoid 85

Permavoid 85 is a 85mm high modular interlocking void former designed for use as a combined drainage component and subbase replacement system. The system is characterized by an exceptionally high compressive strength and bending resistance. The units connected with PermaTies create a rigid horizontal structural ‘raft’, ideal for multifunctional subbase applications.


The system has evolved to a subbase replacement system with aeration, water conveyance, storage, infiltration and irrigation functionality. It effectively combines its high compression strength with the very high void ratio (95%), providing reliable and efficient water conveyance and storage in subbase constructions in SUDS, road-, sports- and rooftop applications.


Using the capillary fibre technology the system is not only suitable for water attenuation and conveyance, but also functions as a sub-soil capillary irrigation system, creating a constant soil moisture content for plants, turf grass or equestrian surfaces.

“The units are designed with tomorrow’s  world in mind. Made from 100% recycled  materials now, and again 100% recyclable  in  the future.”

Ron van Raam, CEO Permavoid 

Key features

  • Creates a shallow (85mm) Sustainable Urban Drainage Systems (SUDS)
  • Replaces gravel subbase, creating a lightweight subbase with 95% open space
  • Suited for stormwater catchment, conveyance, attenuation and irrigation of soil above the system
  • Can be used in conjunction with Permavoid 85, connects with the standard PermaTie.
  • Suitable for water management (catch-store-reuse) in gardens, public green space, greenroofs, podum decks, sports, play and equestrian arenas

Common applications

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