In short, gypsum board is a type of wallboard with a gypsum plaster core bonded to layers of paper or fiberboard used as an alternative to plaster or other types of wallboard to make interior walls. Gypsum board is the generic name for a family of panel-type products consisting of a noncombustible gypsum core, with a paper surfacing on the face, back, and long edges. It differs from other products such as plywood, hardboard, and fiberboard, because of its noncombustible core and is designed to provide a monolithic surface when joints and fastener heads are covered with a joint treatment system.

In our present market there are various types of gypsum board all used for a variety of reasons and needs. Most commonly drywall is 1/2" thick unless needed for fire rated walls where 5/8" is necessary. Gypsum manufacturers are beginning to rely ever more increasingly on “synthetic” gypsum as an effective alternative to natural gypsum ore. Synthetic gypsum is a byproduct primarily from the desulfurization of the flue gases in fossil-fueled power plants.

Fire Resistive
Gypsum board is an very good fire resistive material and is the most commonly used interior finish where fire resistance classifications are demanded. Its noncombustible core contains chemically combined water which, under intense heat, is slowly released as steam, effectively retarding heat transfer. Even after complete calcination, when all the water has been released, it continues to act as a heat insulating barrier. In addition, tests performed in accordance with ASTM E 84 show that gypsum board has a low flame spread index and smoke density index. When installed in combination with other materials it serves to effectively protect building elements from fire for prescribed time periods.