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The Best Floating Floor Underlayment to Install Above Crawl Spaces

The best floating floor underlayment

The best floating floor underlayment

Choosing the best underlayment is perhaps one of the most neglected steps in DIY floating laminate floor installation. And if you have a crawl space below your installation surface, underlayment can either make or break the longevity and integrity of your new flooring. There are six important features to look for to ensure you purchase high-quality underlayment.

Your underlayment should have a high quality vapor barrier.

Your underlayment should have a high quality vapor barrier.

1. Attached Vapor Barrier

Crawl spaces are very common in the mid-western United States, and some other regions as well. Any combination of clay soil, flash flooding, and lower-lying land might bring enough moisture into your crawl space to affect damaging upward vapor into the flooring above. In addition to weakening the flooring with moisture, you might get a moldy smell in the room from traveling vapor.

Even if you have your dirt crawl space covered with its own vapor barrier or 6 mil. plastic sheeting, any sitting moisture on the plastic or barrier from flash flooding or burst pipes can affect your flooring above until you dry out the crawl space.

A vapor barrier for your floating floor helps ensure that moisture does not weaken your new flooring and that any noxious scents do not permeate into the room.

Underlayment needs to provide compression resistance.

Underlayment needs to provide compression resistance.

2. Compression Resistance

When you walk on a floating laminate floor, you want to ensure that the structure of the panels does not wear unevenly over time, leading to cracks, breaks, or low spots. Compression resistance in underlayment helps eliminate this problem. Imagine pushing a spot on a marshmallow down with your finger. The marshmallow fills out to its regular form again. Underlayment with compression resistance provides this same effect to help your floor level stay even over time.

Apply high-quality underlayment above sublooring to deaden sound.

Apply high-quality underlayment above sublooring to deaden sound.

3. Sound-Deadening Quality Above Subfloors

Installing a floating floor over another solid floor poses a problem -- panels hitting each other between levels (also potentially causing damage from impact), and louder noises when shoes hit the floor. Sound-deadening, sound-proofing, or acoustical underlayment all help reduce impact noise. It will also help reduce the general level of echoing in the room. If you have light sleepers in your house or do not want squeaky floors, sound-deadening underlayment is a necessity. If you happen to use a blower or dehumidifier in your crawl space below, its sound travel will also be reduced so that the room above is quieter and more peaceful.

Underlayment should be antimicrobial and resist mold and mildew that might float up escape your subfloor.

Underlayment should be antimicrobial and resist mold and mildew that might float up escape your subfloor.

4. Antimicrobial and Mold and Mildew Resistance

The microbes and potential mold and mildew from humidity that are drawn upwards from crawl spaces should be trapped before it ever has a chance to hit your laminate floating floor. So it is important to choose an underlayment that has the ability to do so. This feature can help prevent people from getting sick due to mold sensitivities and also help keep your airspace clean and healthy.


5. Insulating Value

Keeping the room temperature above your crawl space comfortable involves insulating it from the temperature below. In the winter, your crawl space is cold, and in the spring and summer humidity can make it too warm. In all cases you want to create a barrier so that these different temperatures do not alter the temperature in your living space. An insulating underlayment is important in this case.

Underlayment padding can make walking on your floors much more comfortable.

Underlayment padding can make walking on your floors much more comfortable.

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6. Helps Aid Foot Comfort

If you have ever walked into a big-box store for a shopping trip, you might have come out with aching feet. This is because many stores have completely solid floors. Walking on such floors can radiate discomfort into your feet and legs, and all the way up your back. Having an underlayment at least 1/8" thick can help eliminate the discomfort of walking on a solid floor. This can be especially helpful if you have arthritis, aching joints, or work on your feet all day. A floating floor with a nicely padded underlayment can make all the difference in the physical comfort of walking in your home.

My recommendation for underlayment has the following features:

  • Sound deadening
  • Lifetime compression resistance
  • Attached vapor barrier
  • Added insulating value
  • Antimicrobial and mold and mildew inhibiting
  • Thickness of 1/8" for more walking comfort
  • Free of triclosan
  • Warranted for all flooring brands


  • 100 sq. ft. (33.3 ft. x 36 in.)


  • 1/8-inch


  • 13.3 lbs/ft^3


  • 0.125" = 0.52 hr-ft^2-degF/Btu (4.19/inch)


  • Meets or exceeds Federal Flammability Standard: CPSC FF 1-70 (Pill Test)

MP Global QuietWalk has all of the features mentioned for a moderate price. The qualities mentioned can make a difference in your flooring lasting an extra five to ten years. With such a major expense in both installation time and dollars invested for flooring, helping ensure the health of family and the health and beauty of the home makes MP Global QuietWalk a worthwhile investment.

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