What you should know about subfloor preparation and requirements when it comes to laminate flooring 
installation? Laminate flooring is a floating floor system- meaning it is designated to cover any floor surface without being fixed to it. This makes it possible to cover almost anything –from linoleum to vinyl, ceramic to hardwood, and of course concrete and plywood subfloors. However laminate flooring should be laid only in dry living areas and is not suitable for dump rooms and locations. You must judge whether the subfloor meets the following requirements based on the subfloor type:
Wood Subfloors: The wood subfloor must be level, dry, free of any loose debris, and able to support normally expected loads without deflection. Subfloor variations should not exceed 1/8” in 8’. Subfloors that are not in compliance with these requirements must be leveled and/or repaired prior to installation of laminate flooring. For this application you will be fine using standard laminate underlayment . The best one will be 3mm thick and vapor barrier is not required.
Concrete Subfloors: Concrete subfloors must meet all requirements of a wood subfloor. Additionally in all installations over cement subfloor moisture barrier underlayment must be used to protect your floor against moisture.
Vinyl, Linoleum, Tiles and Sheet Products: You can install laminate floors right over vinyl and linoleum products only when they are in good condition. When these products have been damaged, and you can see loose, torn or uneven areas you need to remove them prior installation. Always use approved underlayment when installing laminate flooring.
Ceramic Tile: Installation over ceramic tiles requires “floating” or filling grout areas that do not conform 1/8” levelness standard with properly prepared and applied leveling compound. Always follow manufacturers leveling instructions and be sure to use approved moisture barrier underlayment with any laminate flooring installation over ceramic tiles.
Carpet: Laminate floors should never be installed over existing carpet. Please note that carpet underlayment is not approved to be used in laminate floor installation, so you have to remove it as well.
Radiant Heated Subfloors: All manufacturers of laminate flooring allowing installation over radiant heated subfloors. This installation requires that the heat must be turned down to 60°F for one week before installation- so that your floor can properly acclimate to the room temperature. When laminate flooring is installed over radiant heated subfloor, make sure the temperature of the heating system is below 80°F all the time and do not turn off the hating if the temperature outside is less than freezing. As with installing over concrete, a vapor barrier underlayment is required to protect your laminate floors against moisture.
HINT: If you decided to install your floor by yourself and in order to ensure that you will enjoy years of pleasurable use, please go through this brief checklist prior installation.
