Flooring Underlayment Guide: Which Type for Which Floor

Underlayment by flooring type

Why the subfloor matters as much as the flooring

The biggest underlayment mistake is treating it as one-size-fits-all rather than matching it to both the flooring material and what's beneath it. Installing over a concrete slab (common in basements and slab-on-grade homes) almost always requires a proper vapor/moisture barrier, since concrete can wick moisture up into the flooring above even when it looks and feels dry — skipping this is a common cause of laminate or engineered wood failing prematurely from moisture damage. Installing over an existing wood subfloor has different priorities, usually focused more on sound dampening and minor subfloor imperfection leveling than moisture blocking.

Pro tip from our network contractors

If you're in a condo or multi-story home, ask your building's requirements before choosing underlayment — many buildings have a minimum sound-transmission rating (like an IIC rating) for flooring over shared ceilings, which dictates a specific underlayment type regardless of what the flooring manufacturer generally recommends.

Don't skip it to save money

Underlayment is a relatively small cost line compared to the flooring material and labor, but it does real work: moisture protection, sound dampening, minor subfloor imperfection leveling, and in some cases meeting a building code or HOA sound requirement. Skipping or downgrading it to save a modest amount upfront is one of the more common regrets in a flooring project, since fixing an underlayment problem later means pulling up the new floor. See flooring cost guide for how underlayment factors into overall project cost.