Thick vs. Thin Underlayment: How to Choose the Right One for Your Project

Company News / 2026-10-30

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When it comes to flooring installation, underlayment is one of those components that’s easy to overlook — but it plays a major role in the long-term performance of the finished floor. A common misconception is that thicker underlayment is always better. In reality, the right choice depends on the flooring type, subfloor condition, and installation environment, not thickness alone.

What Does Underlayment Actually Do?

Underlayment sits between the subfloor and the finished flooring. Depending on the material and construction, it can help with:

Sound reduction
Moisture protection
Thermal insulation
Cushioning and comfort
Floor stability
Subfloor imperfection smoothing

Common underlayment materials include foam, cork, rubber, felt, and composite structures. Each material behaves differently, so thickness should be considered together with density, compressive strength, and moisture resistance.

When Thin Underlayment Is the Better Choice

Thin underlayment is often preferred for floating floors, click-lock systems, and installations where height buildup must be kept to a minimum. Because it provides a firmer base, it helps reduce floor movement and protects locking systems from excessive stress.

It is especially suitable when:

The flooring requires a stable, low-compression base
Door clearances are limited
The new floor must align with adjacent rooms
Radiant heating is installed beneath the flooring
The project involves installing new flooring over an existing floor

In many of these cases, a thin and dense underlayment can deliver better stability than a thicker, softer alternative.

When Thick Underlayment Makes Sense

Thicker underlayment is generally chosen when additional cushioning, sound absorption, or height adjustment is needed. It can be useful in residential spaces where comfort underfoot is a priority, or when the floor height needs to be raised to match surrounding surfaces.

However, if the underlayment is too soft or too thick for the flooring system, it may cause:

Excessive floor movement
Joint separation in click-lock flooring
Reduced efficiency of underfloor heating
Unwanted height differences at doorways and room transitions

Match the Underlayment to the Subfloor

The subfloor condition is just as important as the flooring itself.

Concrete subfloors tend to be dense and may release moisture over time. In these situations, an underlayment with a built-in moisture barrier or strong moisture resistance is often more important than extra thickness.

Wood subfloors are usually drier and less prone to moisture issues. Here, the focus often shifts to sound control, stability, and protecting the locking system, especially in multi-story buildings.

The Bottom Line

There is no single “best” underlayment thickness for every project. Thin underlayment usually offers better stability for floating and click-lock floors, while thicker options can improve comfort and sound performance when the flooring system allows it.