What Is It:
Note that, in the world of flooring, there are two materials that go by the same name of "underlayment." There is the soft kind, the one that is mentioned above and which is the focus of this article. Then there is the hard kind, a thin plywood or fiberboard that is usually about 1/4" inch thick.
Why You Need It:
Without underlayment, your new floor would be hard on your feet. Noises would more easily transmit to floors below, as well as within the room where the laminate is located. Finally, sub-floor imperfections may "telegraph" to the surface of your laminate.
Laminate underlayment will:
- Provide your floor a bit more thermal insulation.
- Bridge minor gaps that subfloors or existing floors have.
- Absorb sound.
- Make it easier for you to walk because it's softer.
- Act as a moisture barrier (though not all will do this; see comments below).
However, length-wise seams are unavoidable. These seams are held in place either by self-adhesive on the underlayment itself or separately with tape.
I've found that there is no need to spend a lot of money on underlayment. Some manufacturers may try to convince you of the need for "designer" underlayment, but no such thing exists. Foam is foam, the only difference being in the thickness of the foam.
Laminate Flooring With Pre-Attached Underlayment:
Not Necessarily a Moisture Barrier:
See also: Laminate Underlayment in Rolls