A self leveling compound is applied to a floor prior to the laying of tile or wood planks. It provides you with a level surface to lay tiles on. Most any floor installer will tell you that you should never lay ceramic tile or wood directly on top of plywood subflooring. Self leveling compound will provide you with the necessary surface to lay the floor.
Clean the Subflooring
Preparing the floor before you pour the self leveling compound involves cleaning up any debris or dirt that has accumulated on the subflooring. This can be done with a shop vacuum or large shop broom. Once you have removed the debris from the subflooring, check the floor for any imperfections. These imperfections include nail or screw heads that may have forced their way upwards. Use a screwdriver or hammer to either remove the screws or nails or put them back in place. Replace any fasteners that you remove with new ones.
Test a Small Area of the Floor
Section off a small area of the floor in order to practice laying the self leveling compound. If you are working with the mixture for the first time, you should practice laying the compound in a small area, in order to get used to using it. Once the compound is mixed with water, you have a finite amount of time in which to work before the mixture becomes hard and unusable.
Source: www.DoItYourself.com