Floating Floor Underlayments

One of the most important yet overlooked products of floating floors is the underlayment. This product is the hidden gem beneath your floor that can separate a good floor from a great floor. The underlayment itself provides a smoother surface for your floor than the subfloor alone, and gives the entire floor better stability.

By definition underlayment is - a layer of material between a subfloor and a finished floor that smoothes minor imperfections in the subflooring surface. In fact many underlayments can offer sound control, moisture control, anti-bacterial, and anti-fungal properties. 

The Basics:

There are 2 required elements that are necessary for your floor to last a long and healthy life; moisture protection and padding (smoothing minor imperfections in subfloor). While not essential in the longevity of the flooring itself, the added benefit of sound control may be a priority for some. Make sure to follow the floor manufacturer’s installation and warranties before deciding on an underlayment.

BronzeStep Installation

Moisture Protection:

This is an important aspect of underlayment as it can prevent costly repairs and replacement of your floor. More importantly it will also protect the health of you and your loved ones from fungi and bacteria that thrive in moist environments. Note that when an underlayment is referred to as 3-in-1, it has the properties of cushioning, sound deadening and moisture protection. Underlayments that have little or no moisture barrier properties must be used in combination with PE (polyethylene) plastic sheeting specified for flooring.


Sound dampening properties are also important and good underlayments can significantly reduce noise inside and below the room. Acoustic properties can be divided into two categories:

STC – In the room sound:

Noise generated in the room and heard by those below the room. This includes airborne sound from TVs, stereos and even conversations and are measured in a test referred to as the Sound Transmission Class (STC)

IIC – Below the room sound:

Noise generated in the room by walking on and moving things across the floor and heard by those in the room below are measured in a test referred to as the Impact Insulation Class (STC).

Within the room sound:

An important factor – but not measured scientifically – is the quality of sound in the room that is related to the underlayment. Depending on the type of flooring, underlayment and subfloor, this is often described as “hollow”, or “solid”. Drop a golf ball on the floor to get a sense of this.

To better understand this, an example is a typical interior wall in your home (1/2″ drywall on either side of a wood stud) that has an STC of about 33. People often describe these walls as "paper thin" as sound travels easily through them.

For STCs and IICs, building codes require a floor rating of 50 (laboratory tested) or better. The higher the number the better sound dampening qualities an underlayment has. Most quality underlayments have been tested and will have this information readily available on packaging or upon request.

Please note that laboratory tests and the specs of your house and building material may result in different ratings.

Types of underlayment:

Knowing what types of underlayment are out there can also help in your buying decision. There are four different types to choose from: fiber, foam, cork and rubber.

Fiber underlayment:

This has some of the best ratings for sound dampening. This will help with the everyday foot traffic and extra noises produced by TV’s and stereos. This, along with moisture control is what you truly want in your bedrooms or living rooms. Some of these fiber underlayments will also insulate cold floors.

PE Foam:

(Including SuperFoam’s EPS beads) is great for potentially moist areas of the house. Although they do have sound dampening capabilities, they are meant for bathrooms, or basements where you might have slightly higher moisture exposure. This underlayment also has a lower cost than fiber underlayment. Some higher quality PE foam underlayments are “cross-linked”. These appear rubbery, soft and are more expensive, but have better ratings all around. SuperFoam is constructed of tough EPS beads that wick moisture to the perimeter. 

BronzeStep PE Foam Stack

Cork underlayment:

Cork is mold and mildew resistant with excellent sound dampening qualities. You will need to add a vapor barrier as it is generally not an adequate moisture barrier. Cork is normally more expensive than most underlayments.

Rubber underlayment:

Very good with sound dampening and has a great moisture barrier. The rubber underlayment however is uncommon, extremely expensive and you can get similar qualities from fiber for half the price.
The CalFlor line of underlayment is designed to cover all the basics and the upgrades. By featuring a wide variety of materials and styles in only 4 SKUs, we believe the consumer’s choice in sound dampening, ease of install, cost effectiveness, and moisture barriers is unsurpassed in the current market.

Fiber Underlayment

Sound-Dampening & Moisture Barrier in ONE

  • Dampens ambient sounds & reduces sound transmission from traveling to rooms below (TESTED: IIC 71, STC 66 & 54).
  • Recommended for use in radiant heat floors and increases R-value (an insulating property).
  • Environmentally friendly product that has over 90% recycled content from by-products destined for landfill.
  • Built-in flap & tape, for added moisture barrier and easy installation.
  • Includes anti-microbial additive, to keep mildew from forming.
  • Made in the USA



Foam Underlayment

Quick Installation, Sound & Moisture Control

  • Accordion style underlayment, built for quick and easy installation (doesn’t roll back on itself).
  • Includes printed grid for quick measuring and cutting.
  • Cross-Linked (closed cell) foam provides protection from both sound and moisture (TESTED: IIC 72 STC 66).
  • Good thermal insulation properties (helps keep room at the temperature you want).


Economical & Covers Basic Needs

  • Suitable for all standard laminate and engineered glue-less floors
  • Smooths minor subfloor imperfections.
  • Includes moisture barrier attached to both sides of the foam.
  • Includes moisture resistant flap and self-sealing tape.