My house is built from concrete there is no cavity and i am getting damp in the corners it is only the external corners and not the room dividing walls its ok once the winter is over there are no air vents either the house was built without any
This sounds more like condensation than damp, it would help a great deal if you were to install "trickle vents" into the window frames, or have a dehumidifier running in the hallway with the doors open slightly. Ray