Does Rigid Vinyl Plank Flooring Need Underdayment?

Purpose of the Underlayment

Flooring underlayment，popular as EVA,IXPE,CORK is a thin material that rests between the floor covering above and the subfloor below. Because underlayment is a catchall term, it can take different forms depending on the flooring material is supports. Unlike the subfloor, which is part of a home's framework and structure, the underlayment serves mostly to provide a flat smooth surface to allow for easy, attractive installation of the surface flooring. It may also serve additional functions, such as to deaden the sound of footsteps, to soften the feeling of the flooring underfoot, and in some cases to act as a moisture barrier.

The primary purposes of underlayment are:

Smooths the surface: Underlayment provides a smoother and more predictable surface for the floor covering than the subfloor, which serves a mostly structural role.

Improves adhesion: In the case of cement board, this underlayment provides a god surface for ceramic tile to bond to. Tile does not adhere well when applied directly to a subfloor, which is known to expand and contract.

Improves structural stability: As a residual effect, a hard underlayment can give the entire floor better stability. It is particularly useful in this function in older homes, where the subfloor may be constructed with boards rather than OSB or plywood sheets.

Underlayment May Not Always Be Necessary

In most major remodeling jobs, the flooring installation will involve laying down some form of underlayment on which to install the surface flooring. But the nature of that underlayment may sometimes be no more substantial than a layer of rosin paper or carpet padding. In brand-new construction, the subfloor may be so sturdy and smooth that carpeting can be laid directly on a carpet padding attached directly to the subfloor, or hardwood flooring can be installed on a simple layer of rosin paper spread over the new subfloor.

More often though, and almost always in remodeling projects, a more substantial underlayment will need to be attached over the subfloor. In cases where the subfloor is in very bad shape, it's even possible that the subfloor itself will need to be removed and a new subfloor layer installed before underlayment and floor covering can be installed. In a bathroom that has seen water damage, for example, the old plywood or OSB subfloor may need to be removed down to the joists, a new subfloor laid, followed by a cement board underlayment, and finally new ceramic tile floor covering.