What is Flooring Underlayment?
Flooring underlayment is either a hard or soft material that is installed under the floor covering and above the subfloor. Flooring underlayment equalizes imperfections in the subfloor, softens and cushions the floor covering to make the floor easier to walk on, protects against moisture, and provides some sound insulation. Plastic sheets, PE Mat, Floorgard and built-in silencio direct on floorboard panels are common underlayments. 
Where Underlayment Fits in a Floor Structure?
Most floors in residential homes consist of four layers. Starting at the top and working downward, these layers are:
1. Floor covering: Floor covering is the finished, visible flooring surfaces, such as SPC Flooring, hardwood planks, carpeting, ceramic tile, or vinyl. Floor covering is the layer that you see and walk on.
2. Underlayment: Just under the visible floor covering is a layer of material the underlayment. The purpose of underlayment is to provide a smooth, flat surface for the floor covering. It can be made of many different materials, chosen depending on the needs of the floor covering.
3. Subfloor: This layer is part of the home's construction and will already be in place when the underlayment and floor covering is installed. Surfaces such as cement, and tiles are common in Malaysia.
Benefits of Flooring Underlayment
Flooring underlayment is a thin material that rests between the floor covering above and the subfloor below. Because underlayment is a catchall term, it can take different forms depending on the flooring material it supports. Unlike the subfloor, which is part of a home's framework and structure, the underlayment serves mostly to provide a flat smooth surface to allow for easy, attractive installation of the surface flooring. It may also serve additional functions, such as deadening the sound of footsteps, softening the feeling of the flooring underfoot, and in some cases acting as a moisture barrier.
The primary purposes of underlayment are:
1. Smooths the surface: Underlayment provides a smoother minor imperfection on the surface for the floor covering than the subfloor, which serves a mostly structural role.
2. Moisture: As a residual effect, an underlayment can give the entire floor a moisture barrier from the ground and minimize the ground moisture from seeping into the floorboard, especially water-resistant type flooring.
Soft Underlayments
They are floating underlayments on top of the subfloor. This means that they are not attached to the subfloor at all. Is a good solution when you are installing a new floor covering directly over an old floor that is still in good shape. For example, a layer of plastic sheet and PE Mat can work well as an underlayment when you are installing laminate flooring over an existing ceramic tile floor and that will make laminate flooring sound and feel less hollow underfoot.
