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All About Underlayments: Purpose, Benefits & Install Tips

by Crystal Hosking - Hosking Hardwood Flooring, Inc. ©2013, Copyright Protected. All Rights Reserved

Underlayments play an important role during the installation of new hardwood flooring or laminate flooring. Whether you intend to staple down, nail down or float, an underlayment offers a slew of benefits during and after installation.

Staple or Nail Down Installation

With a staple down or nail down installation over a wood subfloor using solid flooring or engineered flooring, it is recommended that an underlayment of 15lb. black felt paper is rolled out over the wood subfloor prior to installing the new floor. This hardwood felt paper is necessary to greatly reduce the chance of any moisture coming up through the subfloor and will help protect the new hardwood flooring. Even if you think you don't need it and you're tempted not to use it, it's always better to be safe than sorry. Especially when being sorry could mean $1000's in damage. 15 lb. black felt paper is relatively inexpensive and can be the difference between warped hardwood flooring boards in the future or a floor that stays perfectly beautiful for a lifetime.

15lb. black felt paper for flooring installations over wood subfloors looks a lot like roofing paper, but it is very different. Roofing paper is typically coated with asphalt or tar, which will emit harsh chemical odors, especially if enclosed in your home. Therefore, it's important to make sure the 15lb. black felt paper you're using is manufactured specifically for hardwood flooring installations.

Installation of 15lb. black felt paper is incredibly easy and fast. Simply roll the black felt paper out over the plywood subfloor, overlapping the seams approximately 4 to 6 IN. and then use a hand stapler to attach to the subfloor.

Floating Installation

Underlayments pads are especially important for engineered floors or laminate floors which are installed via the floating method over wood or concrete subfloors. When you float an engineered or laminate floor, none of the boards are actually attached to the subfloor. An underlayment is necessary for multiple reasons, floating floors will expand and contract, moving ever so slightly as a whole unit. The smooth surface of the underlayment allows the flooring on top of it to move slightly during seasonal relative humidty changes. Underlayments are also are used under floating floors to act as a cushion, allowing for a bit of a softer feel when walked upon.

 

 

Some underlayments pads these days are made with an attached plastic moisture retarder. 4-6 mil Plastic moisture retarders are basically non-negotiable when it comes to installing over concrete subfloors, we always recommend the use of a moisture retarder over concrete subfloors. (For underlayments without a moisture barrier attached, you can always install a 6mil plastic sheet separately directly over the concrete slab.)

Underlayment pads also helps to even out subfloors which may have minor imperfections, which is important for a smooth floating installation process.

Lastly, some underlayments pads have exceptional sound absorption properties and can be used as a sort of sound insulator, preventing sound transfer.

There are a multitude of underlayments available for floating installations. They range from simple foam pads to foam pads with a plastic moisture retarders attached to dense felt-like underlayments with remarkable sound absorption properties. Foam pads are typically thinner and their sole purpose is to add a little cushion. Foam pads with moisture barriers attached are also on the thinner side but also offer that moisture protection. The denser underlayment pads (usually a felt like material) are typically a bit thicker and offer more support and insulation because of there dense nature. Please note... that "Regular Carpet padding" is too thick and soft to use as an underlayment pad for any wood or laminate flooring and could cause the joints of the flooring to break when walked on.  

Some hardwood and laminate manufacturers make their own underlayments for floating applications, which they recommend for use with their products. However, in most cases, any industry approved underlayment will get the job done. It's important, prior to installation, to read the specific flooring manufacturer's installation instructions. If they require use of their brand specific underlayment in order for their warranty to be effective, it's always a good idea to acquiesce. 

Installation of underlayment for a floating floor is very simple. Underlayments typically come in rolls. After subfloor prep, simply roll out the underlayment. Many underlayments these days have self-stick overlap flaps for connecting multiple sections of underlayment together. If the underlayment you are using doesn't have these, you can simply use duct tape to secure the edge of one portion of underlayment to the other. (Some flooring manufacturers will sell seam tape, but, really, duct tape works just as well.)

 

One of our top selling underlayments (shown above) is EcoStep underlayment pad is a dense felt-like material, using air-laid filaments. This product is renowned in the hardwood flooring industry as being one of the most advantageous underlayments for floating floors. Features of EcoStep Underlayment include: sound absorption, moisture protection, minimizing of subfloor imperfections, insulation and anti-microbial properties. On top of all that, EcoStep is pretty affordable when compared to similar products in its category (cork or rubber underlayments, which share some of the same properties).

 

Cork Underlayment

Cork underlayments are certainly gaining popularity over synthetic underlayments in both residential and commercial settings. But, what are the major benefits of using a cork underlayment? Cork is a natural product from a renewable source. If you're looking to go more "green" with your home, cork underlayment is a step in the right direction. Cork underlayment also has superior sound deadening qualities more than most any other synthetic underlayments previously mentioned it also helps minimizing subfloor imperfections, adds a degree of insulation and has anti-microbial properties. Many homeowners with allergies love cork as it is naturally anti-bacterial as well as anti-fungal. It's important to remember that cork is naturally water resistant, but not waterproof. Therefore, a 6mil plastic moisture retarder is recommended under the cork for installations over concrete slabs.

Cork underlayments can come in a variety of thicknesses. We've found that the most popular are the 1/8 IN. thick cork underlayment (3mm) and the 1/4 IN. thick cork underlayment (6mm). The only difference is the thickness, the thicker 6 mm will give you twice the sound absorption if desired to lessen any noise when the floor is walked on. Cork underlayments can come in either rolls or sheets. If an installer needs to add height to a subfloor, he'll often choose to use the thicker 1/4 IN. cork underlayment, as most synthetic underlayments measure up at about 1/8 IN. thick.

Cork underlayments are a bit different from other underlayments, because they can be used in staple/nail down installations, floating installations and even in glue down installations. If you plan on installing your flooring via a staple or nail down method with a cork underlyament, you can choose to either float the cork or tack it down to the plywood subfloor. For floating installs, you can either float the cork underlayment or you can tack it down to the subfloor; and then simply install the floating floor on top. If you choose to glue down your engineered hardwood flooring using a cork underlayment underneath you would need to glue the cork down securely to the subfloor and then you can glue the hardwood directly on top of that cork.

Laminate Flooring with Underlayment Attached

Some manufacturers, like QuickStep and Alloc, make laminate flooring with an underlayment already attached to the back of each board. This makes installation quick and simple, negating the need to roll out a separate underlayment. Just keep in mind that if this attached underlayment does not have a moisture barrier attached as well, it's always a good idea to lay one down prior to installing your new laminate floor.

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Web Page: All About Underlayments
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Overall Rating: 4.6 stars - 47 reviews

By:
Date: December 20, 2016
Page Rating: (3.0/5)
Comments:
It says in the article that cork underlayments "CAN" be used in staple/nail down installations. Is this really true? I hear it loses its STC rating b/c of nail penetration.
By:
Date: December 11, 2016
Page Rating: (4.0/5)
Comments:
Thanks for practical advice and not including a lot of advertising in your article.
By:
Date: November 29, 2016
Page Rating: (5.0/5)
Comments:
Very helpful!
By:
Date: November 23, 2016
Page Rating: (5.0/5)
Comments:
Good job very informative
By:
Date: October 28, 2016
Page Rating: (5.0/5)
Comments:
Note * please use the underpayment paper, in my case I used a cheap underpayment paper and now some pieces are gaping meaning coming apart. I believe that the underpayment creates a seal as well and if Im wrong please correct me.
By:
Date: October 6, 2016
Page Rating: (5.0/5)
Comments:
Just wondering.... What are your thoughts about putting plastic as underlayment with wood subfloor and 3/4 nail down oak hardwood?
By:
Date: September 28, 2016
Page Rating: (5.0/5)
Comments:
Excellent article. Really appreciate the information. Thanks
By:
Date: September 28, 2016
Page Rating: (5.0/5)
Comments:
Excellent article. Really appreciate the information. Thanks
By:
Date: September 21, 2016
Page Rating: (5.0/5)
Comments:
Wow, this is one of the best articles on underlayments. I only had one question which I did not see addressed here, I could have missed it, and that was can I double up on cork subflooring because of a difference in height with the old baseboards from a thinner flooring. How thick could someone go. It did say with cork on concrete to use.plastic.which my installer made no mention of so that was helpful. Its a good article, easy to read and.well spread out. Thank you.
By:
Date: September 16, 2016
Page Rating: (5.0/5)
Comments:
thank you for the detailed info you answered all my questions making my decision much easer cork of course thank you

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