Jablite is the UK's largest producer of EPS products for insulation and civil engineering applications



Jablite Claymaster (Clay Heave Protection) is a product that provides protection against clay heave.

Shrinkable clays are soils containing a large proportion of mineral particles of less than 0.002mm in diameter. This produces an extremely cohesive soil type when wet, but shrinks to a crumbly, crazed structure when dry. The expansion and contraction process during wet and dry periods is known as ‘clay heave’. This can cause severe problems with foundations.

Jablite Claymaster works by surrounding the pile cap with a layer of low density, compressible, expanded polystyrene, reducing pressure on the ground beams as the surrounding clay expands and contracts.

Key Benefits
  • A permanent solution to clay heave problems
  • Easy to install
  • Negligible compression during concrete casting
  • No need for specialist trades or equipment
  • Resistant to moisture
  • Lightweight
  • Durable
  • A+ rated in the BRE Green Guide to Specification

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Downloads & Specifications

BBA Certificates and other supporting documents can be found in Technical Resources

Technical Resources
Technical information
Product specification


Jablite Claymaster insulation is supplied:

Board sizes 2400 x 1200mm
Standard thicknesses 50, 75, 100, 150 and 200mm


NHBC Requirements

Thickness of Claymaster to comply with NHBC requirements
Soil heave potential Underside of beam Against side of foundations & beams
NHBC void dimension Equivalent Claymaster NHBC void dimension Equivalent Claymaster
High 150mm 250mm 35mm 75mm
Medium 100mm 175mm 25mm 50mm
Low 50mm 100mm 0mm 0mm
+Which thicknesses are available to order in Claymaster?
There are standard thicknesses which are 50, 75, 100, 150 and 200mm. However, other thicknesses may be available to order.
+When is Claymaster used?
Claymaster is a compressible-fill material used to reduce the pressure against foundations due to clay heave