There are several different schools of thought when it comes to defining the term wallboard. Broadly speaking, it refers to any acceptable material — wood, plastic or gypsum, for example — used to form finished walls in a building. Plywood or strand board sheets could be described as wallboard, along with gypsum-based drywall or formed plastic panels. The term is often used interchangeably with drywall, Sheetrock® or paneling. Some builders strictly define it as the gypsum-based drywall sheets most commonly used in home construction.
It is this second definition that appears to be most common. Wallboard is a synonym for plasterboard or drywall, a product created by sandwiching a layer of gypsum between two paper layers. In the factory,
it begin as one continuous sheet. Special cutters separate this gypsum-and-paper sheet into individual sections of drywall.
The standard wallboard size is generally 4 feet (1.2 m) wide by 8 feet (2.4 m) long, although the length can be as much as 16 feet (4.9 m) for larger projects. The length can be adjusted in 12 inch (300 mm) increments. The average thickness is around 1/2 inch (12 mm), but it can be up to twice as thick.
Wallboard has a number of advantages as a building material. Gypsum is cheap to produce and naturally fire-resistant. Repairs to damaged or broken panels can usually be made by trained homeowners in a few hours. The finished wallboard holds interior and exterior paint well, and can even be plastered over for decorative effect.