History of Laminate Underlayment
The Pergo Company of Sweden invented laminate flooring more than 30 years ago. Designed as a removable floor, laminate flooring is not attached to the subfloor as is hardwood and carpet but rather rests on a foam underlayment. This foam underlayment has traditionally been sold by the roll and is spread out to cover the subfloor before the laminate flooring is installed; it now also is available with the underlayment attached to the individual laminate planks.
Purpose of Underlayment
Underlayment allows a laminate floor to expand and contract only at the perimeter of the room, where an expansion space is hidden by the wall's quarter-round trim. The foam of the underlayment cushions the laminate and allows the flooring to float as a whole piece when subjected to changes in temperature and humidity. In comparison, hardwood floors are nailed or stapled piece by piece directly to the subfloor, and each plank expands and contracts individually. Likewise, carpeting is attached at the edges of the room by tack strips that permanently secure the carpet to the floor. In addition, the underlayment serves to even out slight variations in the subfloor as well as providing sound absorption.
A new development in laminate flooring is to attach the underlayment directly to each plank of laminate rather than laying the underlayment in sheets before the laminate itself is installed. This improvement cuts installation time considerably, thereby cutting the cost of labor. Having the underlayment attached to the plank also alleviates the concern of gapping when installing a rolled underlayment, which can lead to friction and wear beneath the laminate flooring.
Laminate with attached underlayment should not be used in addition to traditional rolled underlayment, as the floating capabilities of the floor system will be compromised. In addition, attached underlayment requires a moisture barrier when installed on concrete. Always take care to follow the laminate manufacturer's underlayment requirements and installation instructions in order to maintain the integrity of your laminate floor warranty.