Gypsum drywall

Drywall (also known as plasterboard, wallboard, gypsum panel, sheet rock, or gypsum board) is a panel made of calcium sulfate dihydrate (gypsum) with or without additives and normally pressed between a facer and a backer (typically thick sheets of paper). It is used to make interior walls and ceilings. The plaster is mixed with fiber (typically paper and/or fibreglass), plasticizer, foaming agent, and various additives that can decrease mildew, increase fire resistance, and lower water absorption.

Drywall construction became prevalent in North America as a speedier alternative to traditional lath and plaster.

The first plasterboard plant in the UK was opened in 1888 in Rochester, Kent. Sackett Board was invented in 1894 by Augustine Sackett and Fred Kane, graduates of Rensselaer Polytechnic Institute. It was made by layering plaster within four plies of wool felt paper. Sheets were 36" × 36" × 1/4" thick with open (untaped) edges.

Gypsum board evolved between 1910 and 1930 beginning with wrapped board edges and elimination of the two inner layers of felt paper in favor of paper-based facings. In 1910 United States Gypsum Corporation bought Sackett Plaster Board Company and by 1917 came out with a product they called Sheetrock. Providing efficiency of installation, it was developed additionally as a measure of fire resistance. Later air entrainment technology made boards lighter and less brittle, then joint treatment materials and systems also evolved. Rock lath (gypsum lath) was an early substrate for plaster. An alternative to traditional wood or metal lath, it was a panel made up of compressed gypsum plaster board that was sometimes grooved or punched with holes to allow wet plaster to key into its surface. As it evolved, it was faced with paper impregnated with gypsum crystals that bonded with the applied facing layer of plaster.

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