A small room with only one door or a basement with water in it is a direct representation of the womb and may indicate a wish to return to the womb-like state of innocence, where everything is taken care of for us.
A series of rooms refers to the various aspects of femininity and often to the whole soul.
An upstairs room usually signifies mental or spiritual attributes, so any object within such a room will represent an idea or concept.
The meaning for a basement or cellar can be ambivalent, since a cellar can represent the parts of ourselves that we have chosen to suppress. It can also represent family beliefs and habits, particularly if the basement is one that belongs to our parents.
If we deliberately leave one room and go into another then it represents a change of state and of leaving something behind. Empty rooms signify that something, such as comfort or support, is lacking in our lives.