Drywall is a common manufactured building material used globally for the finish construction of interior walls and ceilings.

A drywall panel is made of a paper liner wrapped around an inner core made primarily from gypsum plaster, the semi-hydrous form of calcium sulfate (CaSO₄.½ H₂O). The raw gypsum (mined or FGD) must be calcined before use. Flash calciners typically use natural gas today. The plaster is mixed with fiber (typically paper and/or fiberglass), plasticizer, foaming agent, potash as an accelerator, EDTA or other chelate as a retarder, various additives that increase mildew and fire resistance (fiberglass or vermiculite), and water. This is then formed by sandwiching a core of wet gypsum between two sheets of heavy paper or fiberglass mats. When the core sets and is dried in a large drying chamber, the sandwich becomes rigid and strong enough for use as a building material. Drying chambers typically use natural gas today. Depending on plant efficiency and energy costs, 25% to 45% of drywall cost today is related to energy, primarily natural gas.Fact: date=April 2008

Drywall is also commonly known as gypsum board, wallboard, plasterboard (USA,UK, Ireland, Australia, Lebanon), Gibraltar board or gib (New Zealand - GIB being a trademark of Winstone Wallboards), rock lath, Sheetrock (a trademark of United States Gypsum Company), gyproc (Canada, Australia, UK), pladur (Spain - after the Pladur brand), or rigips (Germany and Central Europe - after the Rigips brand), or simply board.

Specifications (USA and Canada)

Drywall is typically available in 4 ft (1219 mm) wide sheets of various lengths. With the rising popularity of high ceilings in new home construction, 4.5 ft (1371 mm) wide panels have become commonly available as well. Newly formed sheets are cut from a belt, the result of a continuous manufacturing process. In some commercial applications, sheets up to are used. Larger sheets make for faster installation, since they reduce the number of joints that must be finished. Often, a sizable quantity of any custom length may be ordered, from factories, to exactly fit ceiling-to-floor on a large project.

The most commonly used drywall is one-half-inch thick but can range from one quarter (6.35 mm) to one inch (25.4 mm). For soundproofing or fire resistance, two layers of drywall are sometimes laid at right angles to each other. In North America, five-eighths-inch-thick drywall with a one-hour fire-resistance rating is often used where fire resistance is desired.