The plastic side faces up and the fiber faces down. Two benefits are provided:
The fibers can actually allow the vapors to evaporate through the gutter system of the underlayment. The fibers are treated with a safe anti-microbial to inhibit mold and mildew.
Protection from Leaks
Spills, leaky plumbing, faulty ice-makers can cause floor damage. QuietWalk underlayment fibers can absorb up to 5 times it’s own weight, drawing harmful moisture in while protecting the overlying floor.