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Underlayment With Moisture Barrier

Underlayment is an added flooring layer between the subfloor and the floor covering. Integrating this layer into a flooring system has various benefits, including thermal insulation, compression resistance, improved acoustic properties, and subfloor leveling. Many underlayments also provide the benefit of moisture protection. 

At floorMuffler®, we offer a variety of underlayments that act as a moisture barrier to maintain the integrity of your flooring system.

Underlayment With Moisture Barrier

A moisture barrier is a protective layer installed between the subfloor and the floor covering to protect the floor covering from moderate amounts of moisture in the subfloor.

When a floor covering, such as hardwood, laminate, or vinyl flooring, is exposed to moisture in the subfloor, the floor covering can become damaged. Moisture in the subfloor may cause the floor covering to become discolored, warped, loose, soft, or spongey. You may notice that the flooring planks begin to buckle or become rippled as a result of moisture damage. The moisture in your subfloor may also lead to the growth of mold and mildew. 

The appearance, lifespan and performance of your flooring can be significantly affected by the presence of moisture in the subfloor. Therefore, it is critical to test your subfloor for the presence of moisture before installing your flooring. An Anhydrous Calcium Chloride Test can be completed to measure the amount of moisture in the subfloor. Make sure that the moisture emission rates do not exceed the floor covering manufacturer’s specifications. Always follow the floor covering manufacturer’s instructions when installing your flooring. Your flooring installation may not be warranted by the floor covering manufacturer if excessive moisture is present in the subfloor.

Finding the Right Underlayment With a Vapor Barrier

Not all underlayments are moisture barriers. Some underlayments require an additional layer or film to form a moisture barrier. FloorMuffler® offers several underlayments with built-in moisture protection that can be used in a variety of hard surface flooring applications. Our top-performing moisture barrier underlayments include:

  • floorMuffler® UltraSeal: Our flagship product is a premium-grade underlayment for commercial and residential installations of laminate, engineered, and solid hardwood flooring. FloorMuffler UltraSeal is made of closed-cell polypropylene foam. The closed-cell structure of the foam makes it incredibly resistant to the transfer of moisture. 
  • floorMuffler® Encore: Many floor coverings come with a pre-attached pad, but these pads often do not provide the same level of moisture protection that a premium underlayment provides. FloorMuffler Encore is the industry’s top-rated underlayment for vinyl plank, rigid core and other attached pad flooring. This underlayment also uses closed-cell technology to protect your flooring from moisture.
  • floorMuffler® LVT: This premium underlayment is designed for luxury vinyl tile and plank flooring that does not have a pre-attached pad. This exceptional moisture barrier is popularly used in commercial projects since it can be either floated or double glued down.

When to Use an Underlayment With Moisture Barrier

Certain floors are more susceptible to moisture damage than others. Here are some of the factors that contribute to the amount of moisture in a subfloor.


Floors that are installed in climates that receive more precipitation and have high-humidity are more likely to be impacted by moisture in the subfloor. A building’s proximity to large bodies of water, could also impact the amount of moisture that exists in the subfloor. The subfloors and foundations of homes can be affected nearby lakes, oceans or marshes. 


Below-grade basements are prone to moisture with soil surrounding the space. Floors on the ground level are also more susceptible to moisture compared to higher floors, and moisture barriers are valuable in these spaces. When installing flooring below-grade, keep in mind that leaking pipes in the basement may contribute to the increased levels of moisture in the subfloor. 

Subfloor Material

Concrete is a standard subfloor material that’s porous and vulnerable to moisture — even in low-humidity areas. It’s recommended that contractors install moisture barriers over concrete subfloor to prevent weakening and cracking caused by excess water vapor. Moisture is also a problem for plywood subfloors, as it can weaken plywood subfloors, putting the entire flooring installation at risk. 

Where to Buy Moisture Barrier Underlayment

You can find premium floorMuffler® underlayments in flooring retail stores throughout the country. FloorMuffler underlayments are sold online and in-store at The Home Depot. 

Speak With the Experts at floorMuffler® Today

Using floorMuffler® underlayment to protect floors from moisture is a valuable investment for contractors and builders. Protect the integrity of the flooring installation with our premium underlayment products. Call 800-440-6008 or contact us online today to learn more about our products.