Foam underlayment
From Floor Coverings
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What is foam underlayment?
Foam Underlayment is a type of padding that is placed between the sub-floor and either laminated flooring or Engineered Hardwood Flooring. These are the two types of flooring that need foam underlayment because these floors are “floating floors”. Floating floors are floors that are not actually attached to the sub-floor. The panels or planks are attached to each other and then placed on top of the foam underlayment. The purpose of foam underlayment is to cover and smooth out minor imperfections in the sub-floor. If you do not install the proper foam underlayment that your new flooring requires, it is possible that your warranty may be voided.
What purpose does foam underlayment have?
Another purpose for installing foam underlayment is to help reduce the sound that you would otherwise make when you walk across flooring that is not attached to the sub-floor and it gives a little bit of cushioning to the feel of a hard floor. If the particular type of foam Foam underlayment has a moisture barrier attached, it also acts to protect the flooring from moisture damage. The thicker the foam underlayment is, the more sound proofing and smoothing out of imperfections it provides. Thicker underlayment does not, however, provide a more cushiony walking experience the way thick carpet padding does.
How many types of underlayment are there?
There are four types of foam underlayment. The most common type is standard foam. Standard foam underlayment is a thin foam padding that measures about 1/8 of an inch thick and provides the least amount of sub-floor smoothing, sound proofing and walking cushion. Standard foam underlayment does not come with a moisture barrier, so it should only be used on floors where moisture buildup or leakage will not be a problem. It is usually sold in 100 square foot rolls.
Where do you use foam underlayment?
A plywood sub-floor is the most likely place that you would use a standard foam underlayment, unless there is a crawl space under the plywood sub-floor. In this case you will need a foam underlayment that has a moisture barrier attached. You could, however, use a standard foam underlayment on a concrete sub-floor only if it happens to be a second story floor that does not need much, if any, sound proofing. But if this floor should also happen to be over a room that will require extensive sound proofing like a recreational room, then you will probably need to install a cork underlayment.
What is the difference between foam and film underlayment?
A combination foam/film underlayment is basically the same type of padding as the standard foam except it does have a moisture barrier attached to one side of it. This barrier prevents moisture from damaging the floor above it. It has the same thickness and provides the same minimal protections from sub-floor imperfections and sound proofing as the standard foam, but it should be used on a base grade floor (first story or entry level) that is a concrete slab or plywood flooring that has a crawl space.
Modified or upgraded foam underlayment is thicker and denser than standard foam underlayment. Walking comfort and sub-floor correcting is the same for modified foam underlayment as it is for standard foam underlayment, but modified foam underlayment does provide the next highest level sound proofing. It is made with a closed-cell foam, fiber or rubber. It is more expensive than cork underlayment and yet does not offer as much sound proofing. Modified foam underlayment comes with or without a moisture barrier. This type of foam underlayment is recommended for second story flooring where extra sound proofing is needed.
What is cork underlayment?
Solid cork underlayment is made with solid cork and is the best option for providing the highest level of sound proofing protection. It can be installed virtually anywhere. Since cork breathes, it naturally resists moisture, but in some cases, a plastic sheeting moisture barrier will still be needed. Cork underlayment is eco-friendly since it is a natural and easily renewable resource. It can also be used on flooring other than “floating floors” like Ceramic tile and bamboo flooring. But if you use cork underlayment on a floor that is not “floating”, you must glue the cork underlayment to the sub-floor. Cork underlayment can be purchased as thick as 7/16 of an inch thick and for this reason can be used to raise the height of a sub-floor to match the height of other floors in the home.
