Drywall

Lore & Background

Drywall is a panel composed of calcium sulfate dihydrate, or gypsum, often mixed with fibers such as paper or glass wool, plasticizers, foaming agents, and additives that reduce mildew, flammability, and water absorption. The wet gypsum core is extruded between two thick sheets of paper or fiberglass mats, then dried in large chambers, becoming rigid and strong. The raw gypsum is heated to remove water and then slightly rehydrated to form the hemihydrate of calcium sulfate. Modern drywall often uses synthetic gypsum produced as a byproduct of flue-gas desulfurization in coal-fired power plants. The board is typically finished with a paper surface on one side and a backing paper on the other. It is used primarily for interior walls and ceilings. Drywall is cut by scoring the finished paper side with a utility knife, snapping the board, and cutting the backing. It is fastened to the structure with nails, drywall screws, or glue, with screws featuring a bugle head that compresses the surface without tearing the paper. The material is lighter and less brittle than earlier versions due to air entrainment technology. Joint treatment systems have evolved to finish the seams between panels. Drywall construction became prevalent in North America in the mid-20th century as a faster alternative to lath and plaster, allowing an entire house to be drywalled in one or two days by two experienced workers.

Reader's Guide

Drywall's significance lies in its transformation of construction practices, reducing installation time from weeks to days and enabling amateur installation. Its manufacture involves heating raw gypsum to drive off water, then rehydrating to hemihydrate, mixing with fibers, plasticizers, foaming agents, and additives for mildew, fire, and water resistance, then sandwiching the wet core between paper sheets and drying. Flue-gas desulfurization gypsum from coal-fired power plants is commonly used. Drywall's legacy includes its role in modern construction efficiency, sound control through multiple layers or specialized boards, and vulnerability to moisture damage due to its gypsum, paper, and organic additives.

Did You Know?

• Sackett Board, the precursor to drywall, was made of plaster layered within four plies of wool felt paper.
• Drywall can be finished from level 0 (no finish) to level 5 (most pristine).

From Sackett Board to Sheetrock: A Century of Evolution

The story of drywall begins in 1890 when Augustine Sackett and Fred L. Kane, both graduates of Rensselaer Polytechnic Institute and employees of the New York Coal Tar Chemical Company, created what they called Sackett Board. Their invention consisted of plaster layered between four plies of wool felt paper, producing 36-by-36-inch sheets just a quarter-inch thick with deliberately open, untaped edges. Over the next two decades, the product underwent significant refinement. Between 1910 and 1930, manufacturers wrapped the board edges and replaced the two inner layers of felt with paper-based facings, streamlining both production and installation. In 1910, United States Gypsum Corporation acquired the Sackett Plaster Board Company, and by 1917 it had launched Sheetrock, a product designed not only for faster installation but also as a deliberate measure against fire. Subsequent innovations in air entrainment made panels lighter and less prone to brittleness, while joint treatment systems continued to evolve. In 1936, US Gypsum trademarked ROCKLATH for its gypsum lath product, which had served as an early substrate for wet plaster applications.

The Chemistry and Craft of Making a Panel

At its core, a drywall panel is a sandwich: a wet gypsum plaster core pressed between two heavy sheets of paper or fiberglass mat. The raw material, calcium sulfate dihydrate, is first heated to drive off water and then slightly rehydrated to yield the hemihydrate form. This plaster is blended with a range of carefully chosen additives—paper or glass fiber for reinforcement, a plasticizer and foaming agent for workability, finely ground gypsum crystal as an accelerator, and chelating agents like EDTA or starch to slow the set. For durability, manufacturers may include wax emulsions or silanes to reduce water absorption, tartaric or boric acid to limit creep, and compounds that resist mildew and flame. Once the wet core is sandwiched between its paper skins, the whole assembly is dried in a large chamber, typically heated by natural gas. Drying a single thousand square feet of board demands roughly 1.85 to 2.63 gigajoules of energy. An interesting twist in the supply chain comes from coal-fired power plants: their flue-gas desulfurization scrubbers capture sulfur using powdered limestone, producing what is called FGD gypsum, a feedstock now widely used in drywall manufacturing across the United States and beyond.

Hanging, Finishing, and the Language of the Trade

What once required a week of wet plaster work can now be accomplished in one or two days by a pair of experienced drywallers, and the material is forgiving enough that many amateur carpenters tackle it in their own homes. In large commercial projects, the work is typically divided between two specialized roles: hangers, who cut and secure the sheets to the framing, and tapers—sometimes called finishers, mud men, or the float crew—who apply joint compound over taped seams and fastener heads. The finished surface can range from a level zero, meaning no finishing at all, up to a level five, the most pristine standard available, with the choice driven by how visible the wall will be to the end user. Cutting a sheet is straightforward: score the paper face with a utility knife, snap the board, and trim the backing. Holes for outlets are cut with a keyhole saw or oscillating tool. Sheets are then fastened with drywall screws whose distinctive bugle head compresses the surface rather than tearing the paper, or with nails, adhesive, and increasingly with specialized drywall clips that replace traditional wood or metal blocking at corners.

A Global Industry and Its Dark Chapter

Drywall goes by a remarkable number of names—plasterboard, dry lining, wallboard, sheet rock, gib board, buster board, turtles board, slap board, custard board, gypsum panel, gyprock—reflecting the many regions and trades that have adopted it. By the mid-twentieth century it had become the dominant interior wall and ceiling material in North America, prized as a time- and labor-saving alternative to the old lath-and-plaster method. The scale of global demand is staggering: in 2020 alone, 8.4 billion square meters of drywall were sold worldwide. Yet the industry's growth was not without controversy. In 2002, the European Commission levied fines totaling 420 million euros against four major producers—Lafarge, BPB, Knauf, and Gyproc Benelux—for operating a cartel that distorted pricing across markets serving roughly 80 percent of consumers in France, the United Kingdom, Germany, and the Benelux countries. The episode underscored how a seemingly mundane building material sits at the intersection of everyday construction, massive industrial chemistry, and the high-stakes economics of multinational manufacturing.