Decoration is a way of honouring the divine and there is much symbolism attached to this from the altar cloths in christian and wiccan religions to food for the spirits in thai buddhist spirit houses. Dreams often access such spiritual knowledge.
Psychological / emotional perspective: When we dream of decorating a room or dwelling place we are aware that changes need to be made in our environment, perhaps to utilize a particular vibration.
Material aspects: Colour may be important in the way we decorate our dream rooms, as may be the articles we choose to have in our environment. When such an article is highlighted it suggests ways of enhancing our day-to-day lives by what it represents.
Gives gender - specific: Men’s and women’s dreams may be very different in terms of the way they adorn their rooms. Traditionally it was thought that women were more drawn to frills and men to sleeker lines.
If the decoration seems out of character we probably need to develop some aspect of creativity.