440SoundBarrier® is a sound-deadening, economical, structural underlayment for finished flooring. Manufactured to resist mold and mildew and UL approved in L500 floor/ceiling assemblies, 440Sound-Barrier® controls sound through all finished flooring: hardwood, laminates, vinyl, carpet and tile. For concrete floors, float ComfortBase, the 2'x3'-engineered panels of 440.