Mr. Walker distinguishes all the generic names that have been given to gypsum board.

Gypsum board is often called by such terms as drywall, plasterboard, wallboard or gypboard.

However, a more precise nomenclature exists to clearly specify and identify each of the different gypsum-based board and panel products. Knowledge about the correct term to use for a gypsum material may help you to avoid confusion regarding the correct material intended for installation on a project.

Board of education

Gypsum board products make up the predominant portion of a family of materials identified as gypsum panel products. They are defined as sheet materials consisting essentially of gypsum. They can be faced with paper or another material, or may be unfaced. Gypsum boards, glass-faced sheathing materials with a gypsum core, and unfaced gypsum-based products are all considered to be gypsum panel products. Formed gypsum trim pieces and sheet products that have a base that is not predominantly gypsum are not considered to be gypsum panel products.

Gypsum board (defined in ASTM Standard C 1396) is a sheet product that has a noncombustible core made primarily of gypsum with paper on its face, back, and long edges. The paper facing characterizes gypsum board within the gypsum panel products family. While all gypsum panel products are sheet materials with a gypsum core, only gypsum board products have a paper facing.

The gypsum board family can be further divided into wallboard and non-wallboard product types. All individual materials within the gypsum board family are referenced in both a specific ASTM manufacturing standard and in the global ASTM manufacturing standard for gypsum board, ASTM C 1396. Identified by their technically correct names and by the appropriate ASTM material specification designations, they are as follows:

As a specific product, Gypsum Wallboard (C 36/1396) is a gypsum board produced primarily for use as an interior surfacing for buildings. It is the most often used commodity gypsum board and annually accounts for more than 50 percent of all the gypsum board manufactured and sold in North America. Gypsum board with manila color face paper usually installed in residential dwellings and many commercial and institutional buildings is gypsum wallboard. This product is manufactured with regular and fire-resistant cores in a variety of thicknesses.

Gypsum Ceiling Board (C 1395/1396) is an interior surfacing material with the same physical appearance as wallboard and is often considered to be a type of gypsum wallboard. Gypsum ceiling board is manufactured as a 1⁄2-inch thick material; it is designed for application on interior ceilings, primarily those intended to receive a water-based texture finish. It has a sag resistance equal to the 5/8-inch thick gypsum wallboard.

Predecorated Gypsum Board (C 960/1396) is also considered to be a type of wallboard. Predecorated gypsum board is manufactured to the same criteria as wallboard (i.e., ASTM C 36) and then surfaced with a decorative material in accordance with the C 960 standard.

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Other gypsum board products for special applications include the following:

Gypsum Backing Board, Gypsum Coreboard and Gypsum Shaftliner Board (C 442) are all designed as base materials in multilayer, solid and semi-solid and shaftwall systems. Gypsum backing board is used as a base layer for other gypsum board materials in systems or as a base for dry claddings such as acoustic tile. Gypsum coreboard and gypsum shaftliner are used to construct systems such as vent shafts, shaftwalls, and area separation walls.

Water-Resistant Gypsum Backing Board (C 630/1396) is a gypsum board designed for use on walls primarily as a base for the application of ceramic or plastic tile. It is readily identified by its green-tinted face paper and is commonly referred to as “Greenboard.” It has a water-resistant core and a water-repellent face and back paper; it is generally installed in bath, kitchen, and laundry areas.

Gypsum Sheathing Board (C 79/1396) is used as a backing for exterior siding or cladding. It has water-repellent face and back paper and may be manufactured with a water-resistant core. Depending on the thickness of the board, gypsum sheathing board may be manufactured with either a square or tongue-and-groove edge. It generally has a brown or light black face paper.

Veneer plaster, a thin gypsum-based plaster material, is applied in one or more coats to Gypsum Base for Veneer Plaster (C 588/1396), a gypsum board that has a face paper treated to facilitate the adhesion of plaster. It is frequently called “blueboard” due to the color created on the face paper during the treatment process. This product should not be confused with Gypsum Lath (C 37/1396), a gypsum board that is used as a base for the application of full thickness gypsum plaster, not gypsum veneer plaster. Gypsum lath is typically manufactured in sheets that are 16 inches wide and with absorbent face paper. By contrast, gypsum base for veneer plaster is produced in sheets that are the same width as wallboard.

Exterior Gypsum Soffit Board (C 931/1396) is designed for installation on exterior soffits, canopies, and other horizontal exterior surfaces that are indirectly exposed to the weather. It has water-repellent face and back paper and is more sag-resistant than regular wallboard, and typically has a light brown face paper. W&C