Plasterboard

Drywall (also called plasterboard, dry lining, wallboard, sheet rock, gypsum board, buster board, custard board, and gypsum panel) is a panel made of calcium sulfate dihydrate (gypsum), with or without additives, typically extruded between thick sheets of facer and backer paper, used in the construction of interior walls and ceilings. The plaster is mixed with fiber (typically paper, glass wool, or a combination of these materials); plasticizer, foaming agent; and additives that can reduce mildew, flammability, and water absorption.

In the middle of the 20th century, drywall construction became prevalent in North America as a time- and labor-saving alternative to lath and plaster.

History

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 thick with open (untaped) edges.

Gypsum board evolved between 1910 and 1930, beginning with wrapped board edges and the 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 introduced ''Sheetrock''. Providing installation efficiency, it was developed additionally as a measure of fire resistance. Later air entrainment technology made boards lighter and less brittle, and joint treatment materials and systems also evolved. Gypsum lath was an early substrate for plaster. An alternative to traditional wood or metal lath 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. In 1936 US Gypsum trademarked ROCKLATH for their gypsum lath product.

In 2002 the European Commission imposed fines totaling €420 million on the companies Lafarge, BPB, Knauf and Gyproc Benelux, which had operated a cartel on the market which affected 80% of consumers in France, the UK, Germany and the Benelux countries.

Manufacture

A wallboard panel consists of a layer of gypsum plaster sandwiched between two layers of paper. The raw gypsum, , is heated to drive off the water and then slightly rehydrated to produce the hemihydrate of calcium sulfate (). The plaster is mixed with fiber (typically paper and/or glass fiber), plasticizer, foaming agent, finely ground gypsum crystal as an accelerator, EDTA, starch or other chelate as a retarder, various additives that may decrease mildew and increase fire resistance, and wax emulsion or silanes for lower water absorption. The board is then formed by sandwiching a core of the wet mixture between two sheets of heavy paper or fiberglass mats. When the core sets, it is dried in a large drying chamber, and the sandwich becomes rigid and strong enough for use as a building material.

Drying chambers typically use natural gas today. To dry of wallboard, between is required. Organic dispersants and plasticizers are used so that the slurry will flow during manufacture and to reduce the water and hence the drying time. Coal-fired power stations include devices called scrubbers to remove sulfur from their exhaust emissions. The sulfur is absorbed by powdered limestone in a process called flue-gas desulfurization (FGD), which produces several new substances. One is called "FGD gypsum". This is commonly used in drywall construction in the United States and elsewhere.

In 2020, 8.4 billion square meters of drywall were sold around the world.

Specifications

Australia and New Zealand

The term ''plasterboard'' is used in Australia and New Zealand. In Australia, the product is often called ''Gyprock'', the name of the largest plasterboard manufacturer. In New Zealand it is also called ''Gibraltar'' and ''Gib board'', after the registered trademark ("GIB") of the locally made product that dominates the market there.

It is made in thicknesses of 10  mm, 13  mm, and 16  mm, and sometimes other thicknesses up to 25  mm. Panels are commonly sold in 1200 × 2400 mm, 1200 × 4800 mm, and 1200 × 6000 mm sheets. Sheets are usually secured to either timber or cold-formed steel frames anywhere from 150 to 300 mm centres along the beam and 400 to 600 mm across members.

In both countries, plasterboard has become a widely used replacement for scrim and sarking walls in renovating 19th- and early 20th-century b