A simple underlayment of foam sheeting is usually sufficient as a base for laminate planks. If the floor surface has damage or unevenness, though, you may need to remove it and lay down a rigid underlayment of thin plywood before laying the foam sheets and installing the laminate flooring.
How to Lay Laminate Flooring: 13 Steps (with Pictures) - wikiHow
Lay plastic lining on the floor of the room that will be covered with the laminate flooring. X Research source Tape the plastic together with a moisture resistant adhesive tape. Make sure to avoid overlapping as you do this because it may cause the floor to rise.
How to Install Laminate Flooring - The Seven Trust
The first thing to know when learning how to lay laminate flooring is that all laminate flooring will expand and contract due to temperature and humidity fluctuations. To allow for this expansion, place 3/8-inch spacers along the wall to leave a consistent gap around the edges of the floor.