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50mm Claymaster

50mm Claymaster
50mm Claymaster
50mm Claymaster
50mm Claymaster
50mm Claymaster
Guide Price: £25.50 (£30.60 inc VAT)
Price per m2: £8.85/m2 (£10.63 inc VAT)
  • Product Code: A1-146
  • Delivery Time: 1-3 working days
  • Brand: Jablite
  • Model and Size: 2400x1200mm - 2.88m2
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50mm Claymaster - Clay Heave Protection

Width: 1200mm
Length: 2400mm
Board Coverage: 2.88m2

50mm Claymaster is an EPS compressible-fill material that helps prevent potential foundation problems caused by moisture movement in soils with a high proportion of mineral particles below 0.002mm (clay heave). It can be used as permanent shuttering for cast in-situ reinforced concrete, relieving pressure on ground beams in piled foundations and the sides of trench fills.

Shrinkable clays consist of a significant proportion of mineral particles smaller than 0.002mm in diameter. When wet, these clays create a highly cohesive soil type that turns crumbly and crazed when dry. This expansion and contraction process, known as clay heave, can lead to serious foundation issues.

Claymaster is a specialised low-density expanded polystyrene material, coloured in pink for easy identification. It is also available in various widths.


The product is suitable for:

  • Supporting concrete ground beams with a maximum depth of 600mm
  • Piled foundation construction
  • The vertical face of deep trench foundations

It helps reduce the pressure exerted on concrete by preventing the expansion of clay soils (clay heave) over the life of the structure.


  • Claymaster offers a rapid and cost-effective solution to clay-heave problems, requiring no specialized trades or equipment
  • For normal ground-beam depths up to 600mm, initial material compression during casting can be disregarded
  • Claymaster is rot-proof, durable, and can withstand below-ground conditions. It remains unaffected by high levels of groundwater or precipitation
  • The boards are typically rectangular and uniform in thickness, but special shapes can be ordered, including circular sections to fit around pile caps and tapered boards
  • According to NHBC Standards, Chapter 4.2 for building near trees, low-density compressible polystyrene is a suitable proprietary material for mitigating ground pressures on foundations in shrinkable soils


Claymaster has undergone assessment by the British Board of Agrement under Regulation A2. It has been proven to reduce the impact of clay soil expansion, which could compromise building stability. The material is approved for use under ground beams and against the sides of deep-trench fill foundations. Certificate number: 90/2543.