What are the different types of insulation? 

There are two different types of insulation material – flexible and solid.  

Flexible insulation is 5mm thick cross-linked closed cell polyethylene foam. This is laid when the floor finish is Hessian backed carpet, laminate or solid wood.

Solid board insulation is 10mm thick and made from extruded polystyrene. This is laid when the floor finish is a ceramic tile, stuck down vinyl  (Amtico/Karndean etc) or carpet tiles.