Why is it always recommended to lay a PE barrier against damp and steam?

The steam-barrier consists of a +/- 0.20 mm-thick plastic sheet (most times Polythene= PE sheet) of PE, or a insulating layer (underlay) that is totally waterproof and prevents moisture passing. Its main function is to prevent moisture gettng in from the subsoil, for example from the ground to the laminate flooring. It is always recommended to use a steam barrier to protect laminate flooring from any problem with moisture that may come from a wet ground. This is particularly important in rooms at the ground level and without basement and in new constructions because maybe the ground was not dried in a correct way (See instructions on how to dry the ground prior to installation) FINfloor Silent and FINfloor PE underlay have already this barrier so it won't be necessary to lay the aditional steam barrier. Anyway, you must make sure of the sealing between rows with adhesive tape (See the instruction sheet on the assembly of the underlay).  more