Foam

• Foam is the standard underlayment for laminate or engineered floating floors. It helps hide minor flaws in the subfloor and provides some sound reduction. The industry standard for regular foam underlayment is 1/8-inch thickness. At this thickness, it does not reduce all sound, or cover all imperfections. Standard foam does not protect against moisture, and is not suitable for use on most concrete slabs or in bathrooms, laundry rooms or kitchens without an additional moisture barrier installed as well. Foam does, however, help make the floor feel slightly softer underfoot.
  
  

Cork

• Cork is more expensive than many other types of underlayment, but offers several advantages. It is environmentally friendly, is excellent at reducing sound, gives laminate flooring a real hardwood feel underfoot and does not trap moisture. It is not designed to be used in moist areas, however, without a moisture barrier. Cork comes in many thicknesses, and thicker cork is typically better at reducing sound. The different thicknesses also allow cork to be used to build up the subfloor to make it even with adjoining floors.
  
  

Foam/Film

• A foam-and-film combination underlayment is designed to give the benefit of standard foam with built-in moisture protection. The film creates a barrier that protects the foam and flooring. A foam-and-film combination underlayment provides the same amount of soundproofing and coverage for imperfections as standard foam, but eliminates the need for installation of a separate moisture barrier.
  
  

Improved Synthetic

• Improved synthetic underlayments offer superior sound protection similar to cork, but with the advantage of a waterproof layer. These underlayments can include high-density foam, rubber and even fabric. They are designed to make laminate and engineered floors sound and feel more like hardwood. Improved synthetic underlayments are also ideal for floors above ground level since they also help dampen sound that travels through to a lower level.