No Underlayment Laminate Floor
Companies like Westhollow® and Pergo® are constantly striving to make laminate floors that are as easy as possible for the weekend do-it-yourselfer. So their newest evolution is to create laminate floors with underlayment attached to the back of each panel.
This process eliminates the cost and labour involved in installing a separate foam underlayment.
This does not eliminate however, the need for a vapour barrier! A vapour barrier in order to be effective, must have as few seams as necessary, thus it is impossible to preapply this to the back of individual panels of laminate flooring. With underlayment attached you can install directly onto wood subfloors BUT a continuous layer of minimum 6mil polyethylene is essential, with a 8"-12" overlap on all the seams, where concrete is the subfloor.
If you are interested in controlling sound transmission to the floor below, with the use of specialized noise reduction laminate underlay, do not purchase laminate floors with underlayment attached. You CANNOT double up on the foam padding. The extra cushioning will create too much movement on the interlocking joints and lead to breakage of the click bond.