Typically an ‘underlayment’ is installed below a vinyl floor to create a moisture resistant seal, to reduce telegraphing (when imperfections on the subfloor are visible through the LVT) and to reduce sound resonance on the floor. In some cases LVT products come with a fiberglass, cork, or foam backing that eliminates the need for underlayment. In these cases the floor can be installed directly onto the subfloor or floating over an older, existing floor.