Drywall panels cover most walls and ceilings built over the last 40 years. These panels have a layer of gypsum sandwiched between heavy paper facings. A waterproof type sometimes called green board is used in bathrooms and other areas subject to heavy moisture. The sheets, which are relatively inexpensive, are 4 feet wide, 1/4 to 5/8 inch thick, and 6 to 16 feet long. The standard size is 1/2 inch thick and 8 feet long.
Drywall sheets are applied to studs, joists, or rafters with drywall nails or screws, or with adhesive. Joints between the panels are covered with a paper or fiberglass tape and coated with several layers of smooth, plasterlike joint compound.
Most ceilings are built with the same materials and methods as walls. They consist of wood framing members joists rather than wall studs and normally are clad with drywall or plaster.
A conventional drywall ceiling consists of drywall panels screwed or nailed to ceiling joists. Joints between the panels are taped and finished with drywall compound using the same methods as for walls. These ceilings are normally hung before the drywall is applied to the walls. Older ceilings often have lath-and-plaster construction.