Bulkhead ceilings can be installed in a variety of different ways depending on their requirements or the design of the building structure.
The most common way to create a ceiling is simply applying plasterboard to the underside of a floor joist or roof truss joist.
Some buildings may require a services void between the underside of a floor joist and a ceiling finish, this is known as a suspended ceiling that will typically be constructed from lightweight metal sections that are suspended from the floor joists to the required depth of service void with a grid type construction of horizontal metal sections fixed to the suspended structs, these sections will support the plasterboard that is screwed to them from below.