Do we really need dilatation joints between rooms?
When a length of more than, for example, 10m is installed in a house, going from one room to another, passing the corridor, etc… then it is possible that this creates tension and possible warping of the laminate floor. This can for example happen when one room is heated and another one not. Another possibility is a heavy piece of furniture in one of the rooms, etc…. It is not absolute necessary to separate all rooms, but technically it is nevertheless advised to separate at least some rooms of the rest, by making a dilatation joint under the door. Finally it is important to mention that HDF is isotrope, and therefore as much “works” in the length as in the width.
from: www.quick-step.com