Precon Products, A leading national independent supplier of construction products



  • Has a nominal compressive strength of 30kN/m² when dry
  • BBA Certified to comply with NHBC Standards
  • Only to be used for Residential projects
  • Offered in 4 thicknesses depending on shrinkage levels
  • Lightweight
  • Cost effective for residential budgets
  • Environmentally Friendly

Clayboard® Residential is a unique, environmentally friendly void former and foundation system to protect against clay heave and ground movement. Clayboard® has a 100% recycled and biodegradable paper honeycomb core set between lightweight polypropylene facings which have up to 70% recycled material content.

When dry, Clayboard® is strong enough to support the weight of wet concrete and steel reinforcement.

Water is introduced to the Clayboard® core once the concrete slab or beam is set, degrading the Clayboard® honeycomb centre which will ultimately lead to the creation of a void and clay heave protection.

This space will accommodate clay expansion without exerting undue pressure on the structure above. The resulting void continues to accommodate natural soil shrinkage and expansion.


Clayboard® is supplied in panels 2440mm long by 1000mm wide, by the specified thickness. Clayboard® is delivered to site on lightweight pads for easy unloading, and is polythene wrapped for protection.


The thickness of Clayboard® depends on the depth of the required void which should be specified by the soil engineers taking into account the plasticity index.

Compressive strength

Clayboard® is available in two standard strengths, KN30 (Residential) and KN90 (Commercial). KN30 has a nominal compressive strength of 30kN/m² when dry and is designed to support the weight of wet concrete up to 1m thick. KN90 has a nominal compressive strength of 90kN/m² when dry and is recommended for concrete slabs thicker than 1m.

When the core is wetted, both KN30 and KN90 Clayboard® will collapse under nominal compressive load of approximately 3kN/m².

Health and Safety for our void fillers

The materials used in Clayboard® do not constitute a risk to the Health and Safety of users in the course of site application in the recommended manner. It is the user’s responsibility to adopt relevant safe practices when handling, stacking, cutting and installing Clayboard® panels. Clayboard® panels are safe to handle with no dust and no harmful emissions.

Clayboard Void Shrinkage
160mm 150mm High Shrinkage
110mm 100mm Meduim Shrinkage
85mm 75mm Medium Shrinkage
60mm 50mm Low Shrinkage

Also available

  • Void pak pipes
  • Pre-wrapping service 
  • Commercial clayboard
Clayboard main image


  • Clayboard illustration
  • Clayboard illustration

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