i have a damp problem on the gable end of my 3 story terrace. The house next door is 2 story but the problem comes from above where their roof joins, rulling out a problem with the flashing. reading your topics page leads me to suspect condensation as it is worse behind furniture where it tends to go mouldy, but is also making the plaster bubble. the wall is single brick thick, and the problem is confined to the gable end. if i buy a dehumidifier would this cure the problem and will i have to replaster? help greatfully recieved.