Hi had bedroom boarded and skimmed 2 weeks ago, there was a couple of hair line cracks that appeared as it dried out,we filled them and gave it a mist coat of watered down white paint, we then left the room for a week and when we checked it again yesterday all the walls and ceiling had cracks showing the outline of nearly every board, not hair line cracks like before but thick deep cracks, plasterer has came back today and said its because we have turned the heating off in that room and with it being an old property with solid walls and single glazing and how cold it has been it is the plaster shrinking etc due to the drop in temperature. Is this correct? It is cold in there but Im worried the cracks are going to come back