Sheetrock® is the trade name for USG Corporation's drywall product, called by a variety of names in different countries, including gypsum board, wallboard, plasterboard, Gibraltar board, GIB wall, ceiling linings, and rock lath. Manufactured in dimensions specifically designed to meet construction standards set forth in building codes, it dramatically reduces the time required to erect interior walls and ceilings in any structure. While there are different approaches to Sheetrock® installation, there's also substantial agreement on some approaches in particular circumstances, particularly in new construction.
Sheetrock® is manufactured and sold in dimensions of 48 inches (120 cm) wide by a number of different lengths, most often either 96 inches (240 cm) or 144 inches (366 cm) long. Most building codes require that studs – beams of wood or hollow steel that support interior walls – be positioned 16 inches (40.6 cm) apart on-center, or from the center of one stud to the center of the next is 16 inches. The standard ceiling height is eight feet (2.44 m). Sheetrock's® standard dimensions facilitate positioning it either horizontally or vertically, and each approach has many proponents.
In either case, there are some important points to keep in mind. First, every vertical edge of Sheetrock® should be fastened to a stud; there should never be a hollow space behind a vertical Sheetrock® joint. Second, the edge of a Sheetrock® panel should not run parallel to a door or window frame; rather, the panel should be cut to accommodate the frame. This will reduce the potential for problems operating a door due to bulges created in the taping process. Also, if Sheetrock® joints follow the lines of a door or window frame, there will be a greater tendency for the joints to give way to the stress of operation, requiring repair. Another critical point is that ceiling Sheetrock® installation should take place before walls, so that the Sheetrock® subsequently installed on the walls can help support the edges of the ceiling Sheetrock®.
Sheetrock® installation on a ceiling can be difficult, and generally requires at least two people, although there are special Sheetrock® lifts that will hoist a panel of Sheetrock® up to a ceiling for fastening to ceiling joists. Alternately, simple drywall jacks made of 2x4s will enable two people to wedge support underneath a Sheetrock® panel while they fasten it to the ceiling joists.
When fastening Sheetrock® to studs, some installers use drywall nails and a special hammer with a convex striking surface that will “dimple” the Sheetrock® surface without breaking the paper skin. Another popular method is to use special drywall screws, with an electric drill and a special drill bit that will countersink the screw head just below the Sheetrock's® skin, again dimpling the paper without breaking it. Screws have less of a tendency to pull loose from studs, and a good dimpling drill bit will make screwing Sheetrock® to studs a quick job. A screw or nail should be installed every nine to 12 inches along the line where the Sheetrock® panel meets a stud or ceiling joist. Some do-it-yourselfers simply apply a bead of construction adhesive to the studs and press the Sheetrock® panels to them, but this is not a widely accepted practice. Where two Sheetrock® panels meet, they should be butted tightly against each other and the two edges fastened securely to the underlying stud.
Once Sheetrock® installation is complete, it is usually “finished” — that is, all evidence of installation is covered up. The joints and screw heads are covered and smoothed over to present the appearance of a single flat surface, ready for painting. This is done by application of paper or cloth tape along all joints, over which a thin coat of joint compound is spread with a special tool called a taping knife. Inside corners are treated the same with a folded piece of tape. Outside corners are treated with an aluminum corner strip, which is nailed in place and covered with compound, and screw heads are also covered with compound. When dry, the compound is carefully sanded and the process is repeated. Depending on the wall's use and the material that will cover it, this step may be repeated a number of times, with the objective being a perfectly smooth and flat finish with no ridges or tool marks.