Ceiling vents can be attached to the outside surface of the drywall by using drywall anchors to prevent it from crumbling. If no drywall anchors are available, ceiling vents should be attached to the joists that are located above a drywall ceiling instead.
It is also recommended that the ceiling vent that is attached to a drywall be lightweight. As of 2015, there are both plastic and light aluminium ceiling vents available on the market. Heavier vents can stress a drywall ceiling and cause it to fall off with time. A ceiling vent's main function is to keep dust and other contaminants from an exhaust duct from entering living spaces when the furnace is in operation.