Drywall – Wikipedia, the free encyclopedia

Drywall (also known as plasterboard, wallboard, gypsum board, sheetrock, or gyprock) is a panel made of gypsum plaster pressed between two thick sheets of paper. It is used to make interior walls and ceilings. Drywall construction became prevalent as a speedier alternative to traditional lath and plaster.[1]

In many places, the product is sold under the trademarks Sheetrock[2] or Gyproc.[3][4][5] In New Zealand the category is known as "plasterboard" or "gib board" (originally "Gibraltar board"), the latter being a proprietary brand name but now largely a genericised trademark.[6][7][8][9]

The first plasterboard plant in the UK was opened in 1888 in Rochester Kent.[citation needed]Sackett Board was invented in 1894 by Augustine Sackett and Fred Kane. It was made by layering plaster within four plies of wool felt paper. Sheets were 36" 36" 1/4" thick with open (untaped) edges.[10]

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 19109 United States Gypsum Corporation bought Sackett Plaster Board Company and by 1917 came out with a product they called sheetrock.[11] Providing efficiency of installation, it was developed additionally as a measure of fire resistance.[12] Later air entrainment technology made boards lighter and less brittle, then joint treatment materials and systems also evolved.[10]

Rock 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.[13]

A wallboard panel is made of a paper liner wrapped around an inner core made primarily from gypsum plaster. The raw gypsum, CaSO42 H2O, (mined or obtained from flue-gas desulfurization (FGD)) must be calcined before use to produce the hemihydrate of calcium sulfate (CaSO4 H2O). This is done in kettle or flash calciners, typically using natural gas today. The plaster is mixed with fiber (typically paper and/or fiberglass), 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 (fiberglass or vermiculite), wax emulsion or silanes for lower water absorption and water. This is then formed by sandwiching a core of wet gypsum between two sheets of heavy paper or fiberglass mats. When the core sets and is dried in a large drying chamber, the sandwich becomes rigid and strong enough for use as a building material.

Drying chambers typically use natural gas today. To dry 1 MSF ( 1,000 square feet (93m2) ) of wallboard, between 1.75 and 2.49 million BTU is required. Organic dispersants/plasticisers are used mainly to reduce the amount of water, hence reduce the eventual drying time, needed to produce gypsum slurry flow during wallboard manufacture.[14]

Drywall panels are manufactured in 48-inch (1.2m) and 96-inch (2.4m) wide panels in varying lengths to suit the application. Common panel thicknesses are 12-inch (13mm) and 58-inch (16mm), with panels also available in 14-inch (6.4mm) and 38-inch (9.5mm). Both 12-inch and 58-inch panels of Type X (a gypsum board with special core additives to increase the natural fire resistance of regular gypsum board[15]) are used where a fire-resistance rating is desired. Sound transmission may be slightly reduced using regular 58-inch panels (with or without light-gauge resilient metal channels) but more effective are using two layers of drywall sometimes in combination with other factors or specially designed, sound-resistant drywall.[16]

Drywall provides a thermal resistance R-value (in US units) of 0.32 for 38-inch board, 0.45 for 12-inch, 0.56 for 58-inch, and 0.83 for 1-inch board. In addition to increased R-value, thicker drywall has a higher sound transmission class.[citation needed]

In Europe plasterboard is manufactured in metric sizes, with the common sizes being corollaries of old imperial sizes.

Continue reading here:
Drywall - Wikipedia, the free encyclopedia