Sheetrock is a brand of drywall that is a registered trademark of the U.S. Gypsum Company. With the exception of a couple of chemicals that allow the Sheetrock formula to be patented, there is practically no difference between Sheetrock and other drywall. Either can be used as construction material for walls and ceilings. However, not all drywall is created equal: some drywall material has high sulfur content that can prove problematic for buildings and health.
What is Drywall?
Drywall is a panel made of gypsum plaster sandwiched between thick paper. It is used in the construction of interior walls and ceilings as a replacement for the traditional lath and plaster method. Other names for drywall panels are plasterboard, wallboard, gypsum board, gyprock, and Sheetrock.
What is Sheetrock?
Sheetrock is a brand of drywall, though because of its popularity, the term has come to be used interchangeably with drywall. Sheetrock is also used as a replacement for lath and plaster in the construction of interior ceilings and walls, though some Sheetrock is weatherproofed for exterior ceilings.
Only the U.S. Gypsum Company may market their drywall as Sheetrock. However, other companies that make drywall are: National Gypsum Company, Titan Commercial Products, and Allied Manufacturing.
Drywall comes in several different types. Standard panels can come in 1/4-inch to 3/4-inch thickness. Fire-resistant drywall features additives to increase this property. Greenboard features green paper, to which an oil-based additive is used to provide moisture resistance. Similarly, blueboard utilizes additives that make the paper both water and mold resistant. Cement board is even more water resistant. Mold-resistant drywall has no paper. Soundboard uses wood fibers to increase sound transmission while soundproof drywall uses damping polymers to decrease sound transmission. Enviroboard is made from recycled agricultural materials. Drywall can be lead-lined for use around radiological equipment or foil-backed as a vapor barrier.
Sheetrock also comes in different varieties, including the regular core panels in 1/4-inch, 3/8-inch and 1/2-inch thicknesses. There are three grades of fire-resistant panels, including one with a 3/4-inch Ultracode core. Like regular drywall, Sheetrock also comes in a foil-back variety as well as a mold and moisture-resistant option, including the Fiberock panel with is the top choice for this necessity. Sag-resistant Sheetrock is light-weight, thus resisting sagging. Exterior ceiling board is weather-resistant, so it can be used outdoors. Finally, Sheetrock offers stronger panels that are resistant to abuse such as indentations, abrasion and even penetration.
Drywall consists of a core of gypsum plaster pressed between two thick sheets of paper. The gypsum plaster core is made out of fiber, a foaming agent, finely ground gypsum crystal and additives. To make drywall, the wet gypsum core gets sandwiched between heavy paper or fiberglass mats.
This manufacturing process is the same for the Sheetrock brand, but for the use of a few chemicals unique to the brand. However, even that comes under the classification drywall.
Both drywall and Sheetrock are used with the same basic techniques. Construction workers cut the panel to size, usually by scoring the paper and breaking the core manually. The sized panels are fixed to wall studs or ceiling joists with nails, glue, drywall screws or drywall fasteners. The remaining seams are concealed using a joint compound filler and tape. In some cases, the drywall then gets further sealed with veneer plaster. Using a veneer makes for a smoother wall.
Benefits and Disadvantages
One advantage of using drywall or Sheetrock is that it only takes a day or two to do unlike the week-long process of the lath and plaster method. Utilizing special construction methods, such as building thicker walls with drywall, offers some sound control. Additionally, due to the water of crystallization in gypsum, drywall offers some fire resistance.
Drywall and Sheetrock can be damaged from water exposure, resulting in unsightly wicking and even softening of the plaster. Likewise, the paper used in both supports the growth of mold. Lastly, in construction, workers waste up to 17 percent of the material in cutting the panels to size.
A disadvantage found in some non-Sheetrock brands is that they emit sulfur gases; this has been especially true of drywall imported from China, but sulfur emission has been found in non-Sheetrock, U.S.-made drywall material as well. Drywall with high sulfur content, which results in foul odors, negative health effects, and metal corrosion, was used frequently during the rebuilding efforts following Hurricane Katrina in 2006. The full extent of sulfur gases' effects on health is not entirely known because few studies have been done, but the CDC has a guide for healthcare providers on imported drywall's potential effects.
Drywall and Sheetrock came into common use starting around World War II. The prototype for drywall was Sackett Board, invented in 1894 by Augustine Sackett and Fred Kane. Plaster was layered between four layers of wool felt paper. The U.S. Gypsum Company started evolving this Sackett Board into Gypsum Board between 1910 and 1930. In this evolution, gypsum plaster replaced traditional plaster in the core. In 1917, the US Gypsum Company first introduced the Sheetrock board panels in the form common today.