Furr downs

The lowered portion of a ceiling above a cabinet or closet. The most common use for a furr down is to improve the appearance of a cabinet by closing the opening between the ceiling and the top of a cabinet.  In older construction these were often left open to attic spaces and may not have been insulated.  In modern construction these should be covered with an air sealed cover in the attic space and insulated to prevent infiltration air or energy loss.