Claylite is a low density expanded polystyrene compressible fill boardwhich acts to absorb ground movement caused by clayheave, shrinkage or other soil movements.
Sheet size 2400mm x 1200mm. Available in four grades and 50mm, 75mm or 100mm thicknesses.

Low density foam insulation board with foil facing, manufacturers include
Celotex, Kingspan and Poltfoam.
Available in various grades and thicknesses.