Drywall is made of gypsum plaster, which is pressed between two thick sheets of paper to create panels. Drywall may also be called plasterboard, wallboard or gypsum board. North America is the top user of drywall in the world.
Gypsum, the material that makes up drywall, is mostly calcium sulfate and water. In order to create the plaster it is mixed with paper or fiberglass, plasticizer, foaming agent, starch and additives that help reduce mildew. These additives also help reduce the flammability of the drywall. The paper and make-up of the drywall can vary depending on the intended use. The typical drywall has paper or fiberglass covering over the plaster. If the drywall is meant to be used someplace that has more water exposure, like a bathroom, then a type of drywall called cement board is used; cement board is also a good base for ceramic tiles. Greenboard is also used in washrooms and water usage areas because it has special oil additives to help with water resistance. This type of board does well in high humidity areas. Blueboard is another type that is used in areas with high water usage. It has a paper finish that bonds with a skim coat of plaster, which helps it resist water and mildew.