Are there any major disadvantages to insulating interior walls including ceilings/floors of a split level ranch house witha walkout finished basement? My reasons for insulating would be for sound deadening purposes. I dont mean every wall in the house, but probably the downstairs den (walls and ceiling) and 2 bathrooms and possibly the master bedroom. I thought I remember reading somewhere that it is not a good idea for airflow or something but I cant remember exactly.