Floor Underlayment Performance

We have already seen how a properly performing fibrous underlayment can enhance acoustical design and performance in an interior space. In addition, protecting finished hardwood and laminated flooring from moisture can be critically important to the long-term durability of such flooring. Fibrous underlayment with an attached vapor barrier addresses this performance concern by helping to manage moisture and protect the finished floor. Duane Reimer, technical director of MP Global Products, noted, “Moisture management should address moisture that can come from either below or above the underlayment. Quality underlayment for laminate flooring should be able to absorb incidental moisture coming up from a concrete subfloor without swelling or deteriorating and should feature an attached vapor barrier on the top side that keeps harmful moisture away from the laminate floor.” This method of controlling the flow of moisture and protecting finished flooring can often make all the difference in the end user's satisfaction with the flooring.

In addition to moisture, the underlayment needs to be soft enough to absorb irregularities in the flatness of the subfloor including nail-heads and seams. On the other hand, it needs to be firm enough to keep a typical tongue-and-groove locking system from bending, and possibly breaking, if the seams are compressed under heavy load. Hence a properly selected underlayment can contribute to the overall integrity of the flooring on top of it.

Underlayments that are made from fibrous materials often feature recycled content from discarded fibers that are diverted from a landfill. The fibers can undergo a manufacturing process that results in randomly laid fibers in various directions and of differing length. This tends to give the fibers more tensile strength without creating holes as would be typical in a needle-punch process. Further, the randomly laid fibers enable the underlayment to wick in moisture, absorb, and then dissipate it.

Photos courtesy of MP Global Products

Fibrous underlayment beneath wood flooring can be a key contributor in controlling moisture and protecting the integrity of the finish flooring.