Modified or Upgraded Flooring Underlayment

What is it? – Modified or upgraded underlayments are usually thicker and/or denser than standard foam. These underlayments can be constructed from high-density foam, closed-cell foam, fiber, or rubber. Their main purpose is to provide better sound reduction than the standard foam type. The comfort level and sub-floor correction ability would be the same as with standard foam and combo underlayments. In most cases, modified or upgraded underlayments do not offer the same level of sound reduction as cork underlayment, and they cost more. We’ll discuss the features of cork in the next section. As with the other underlayments, manufacturers of the modified or upgraded types have their own brand names. However, unlike the other underlayments, they will vary in thickness, type of construction, sound reduction levels, and overall quality. Also, they may or may not be available with an attached moisture barrier. Where is it used? – Modified or upgraded underlayments are used to reduce sound and therefore, are primarily used on second floor levels or higher. While they are more effective than the standard foam or foam/film types, in most cases they are not as effective as cork. These types of underlayments should not be considered as "added comfort," only as added sound reduction. Note: If you live on the second floor, or higher, of a condo building, there may be rules that dictate the type of underlayment required. The requirement may call for one that reduces sound even more than the modified or upgraded types. In such cases, cork is often the specified underlayment. However, if cork is not specified, then we highly recommend Floor Muffler as a less expensive alternative that will provide excellent sound reduction. If you do live in a condo, we strongly suggest getting a copy of the rules and verifying their requirements before buying any material. We also suggest that you get a letter signed by the condo board, prior to starting any flooring work, stating that your choice of underlayment is acceptable.