Sagging Ceilings
A sagging ceiling can generally be renewed with a minimum of trouble by fixing timber battens and plasterboard sheets below it.
The humidity experienced in many parts of Australia can cause ordinary plasterboard ceilings to sag between the ceiling and partition, especially as wider spacings are now more common.
A sagging ceiling will be most noticeable at night when the lights are on. You will be able to see one or more very visible lines running across the ceiling.