American Gypsum Company LLC has been manufacturing, selling, and distributing gypsum wallboard products for over half a century, servicing the drywall industry with quality products that are sold throughout the United States.
Drywall (also called plasterboard, dry lining,[1] wallboard, sheet rock, gypsum board, buster board, slap board, custard board, and gypsum panel) is a panel made of calcium sulfate dihydrate (gypsum), with or without additives, typically extruded between thick sheets of facer and backer paper, used in the construction of interior walls and ceilings.[2] The plaster is mixed with fiber (typically paper, glass wool, or a combination of these materials); plasticizer, foaming agent; and additives that can reduce mildew, flammability, and water absorption.
Type Of Gypsum Board Pdf To Jpg
Gypsum board evolved between 1910 and 1930, beginning with wrapped board edges and the elimination of the two inner layers of felt paper in favor of paper-based facings. In 1910 United States Gypsum Corporation bought Sackett Plaster Board Company and by 1917 introduced Sheetrock.[5] Providing installation efficiency, it was developed additionally as a measure of fire resistance. Later air entrainment technology made boards lighter and less brittle, and joint treatment materials and systems also evolved.[4] Gypsum lath was an early substrate for plaster. An alternative to traditional wood or metal lath 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.[6] In 1936 US Gypsum trademarked ROCKLATH[7] for their gypsum lath product.
A wallboard panel consists of a layer of gypsum plaster sandwiched between two layers of paper. The raw gypsum, .mw-parser-output .template-chem2-sudisplay:inline-block;font-size:80%;line-height:1;vertical-align:-0.35em.mw-parser-output .template-chem2-su>spandisplay:block;text-align:left.mw-parser-output sub.template-chem2-subfont-size:80%;vertical-align:-0.35em.mw-parser-output sup.template-chem2-supfont-size:80%;vertical-align:0.65emCaSO42H2O, is heated to drive off the water and then slightly rehydrated to produce the hemihydrate of calcium sulfate (CaSO4.mw-parser-output .sfracwhite-space:nowrap.mw-parser-output .sfrac.tion,.mw-parser-output .sfrac .tiondisplay:inline-block;vertical-align:-0.5em;font-size:85%;text-align:center.mw-parser-output .sfrac .num,.mw-parser-output .sfrac .dendisplay:block;line-height:1em;margin:0 0.1em.mw-parser-output .sfrac .denborder-top:1px solid.mw-parser-output .sr-onlyborder:0;clip:rect(0,0,0,0);height:1px;margin:-1px;overflow:hidden;padding:0;position:absolute;width:1px1/2H2O). The plaster is mixed with fiber (typically paper and/or glass fiber), 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, and wax emulsion or silanes for lower water absorption. The board is then formed by sandwiching a core of the wet mixture between two sheets of heavy paper or fiberglass mats. When the core sets, it is dried in a large drying chamber, and the sandwich becomes rigid and strong enough for use as a building material.
The term plasterboard is used in Australia and New Zealand. In Australia, the product is often called Gyprock, the name of the largest plasterboard manufacturer.[13] In New Zealand it is also called Gibraltar and Gib board,[14] after the registered trademark ("GIB") of the locally made product that dominates the market there.[15][16]
Plasterboard is commonly made with one of three edge treatments: tapered edge, where the long edges of the board are tapered with a wide bevel at the front to allow jointing materials to be finished flush with the main board face; plain edge, used where the whole surface will receive a thin coating (skim coat) of finishing plaster; and beveled on all four sides, used in products specialized for roofing. Major UK manufacturers do not offer four-sided chamfered drywall for general use.
As an alternative to a week-long plaster application, an entire house can be drywalled in one or two days by two experienced drywallers, and drywall is easy enough to be installed by many amateur home carpenters. In large-scale commercial construction, the work of installing and finishing drywall is often split between drywall mechanics, or hangers, who install the wallboard, and tapers and mud men, or float crew, who finish the joints and cover the fastener heads with drywall compound.[citation needed] Drywall can be finished anywhere from a level 0 to a level 5, where 0 is not finished in any fashion, and five is the most pristine. Depending on how significant the finish is to the customer, the extra steps in the finish may or may not be necessary, though priming and painting of drywall are recommended in any location where it may be exposed to any wear.
Drywall is highly vulnerable to moisture due to the inherent properties of the materials that constitute it: gypsum, paper, and organic additives and binders. Gypsum will soften with exposure to moisture and eventually turn into a gooey paste with prolonged immersion, such as during a flood. During such incidents, some, or all, of the drywall in an entire building will need to be removed and replaced. Furthermore, the paper facings and organic additives mixed with the gypsum core are food for mold.
Drywall's paper facings are edible to termites, which can eat the paper if they infest a wall cavity covered with drywall. This causes the painted surface to crumble to the touch, its paper backing material being eaten. In addition to the necessity of patching the damaged surface and repainting, if enough of the paper has been eaten, the gypsum core can easily crack or crumble without it, and the drywall must be removed and replaced.
A substantial amount of defective drywall was imported into the United States from China and incorporated into tens of thousands of homes during rebuilding in 2006 and 2007 following Hurricane Katrina and in other places. Complaints included the structure's foul odour, health effects, and metal corrosion. The emission of sulfurous gases causes this. The same drywall was sold in Asia without problems resulting,[citation needed] but US homes are built much more tightly than homes in China, with less ventilation. Volatile sulfur compounds, including hydrogen sulfide, have been detected as emissions from the imported drywall and may be linked to health problems. These compounds are emitted from many different types of drywall.
Some fire barrier walls are constructed of Type X drywall as a passive fire protection item. Gypsum contains the water of crystallization bound in the form of hydrates. When exposed to heat or fire, this water is vaporized, which retards heat transfer until the water in the gypsum is gone. The fire-resistance rating of the fire barrier assembly is increased with additional layers of drywall, up to four hours for walls and three hours for floor/ceiling assemblies.[25] Fire-rated assemblies constructed of drywall are documented in design or certification listing catalogues, including DIN 4102 Part 4 and the Canadian Building Code, Underwriters Laboratories and Underwriters Laboratories of Canada (ULC).
In the Type X gypsum board, special glass fibers are intermixed with the gypsum to reinforce the core of the panels. These fibers reduce the size of the cracks that form as the water is driven off, thereby extending the length of time the gypsum panels resist fire without failure.[26]
Type C gypsum panels provide stronger fire resistance than Type X. The core of Type C panels contains a higher density of glass fibers. The core of Type C panels also contains vermiculite which acts as a shrinkage-compensating additive that expands when exposed to elevated temperatures of a fire. This expansion occurs at roughly the same temperature as the calcination of the gypsum in the core, allowing the core of the Type C panels to remain dimensionally stable in a fire.[26]
North America is one of the largest gypsum board users in the world, with a total wallboard plant capacity of 42 billion square feet (3.9 billion square metres) per year, roughly half of the worldwide annual production capacity of 85 billion square feet (7.9 billion square metres).[27] Moreover, the homebuilding and remodeling markets in North America in the late 1990s and early 2000s increased demand. The gypsum board market was one of the biggest beneficiaries of the housing boom as "an average new American home contains more than 7.31 metric tons of gypsum."[28]
The introduction in March 2005 of the Clean Air Interstate Rule by the United States Environmental Protection Agency requires fossil-fuel power plants to "cut sulfur dioxide emissions by 73%" by 2018.[29] The Clean Air Interstate Rule also requested that the power plants install new scrubbers (industrial pollution control devices) to remove sulfur dioxide present in the output waste gas. Scrubbers use the technique of flue-gas desulfurization (FGD), which produces synthetic gypsum as a usable by-product. In response to the new supply of this raw material, the gypsum board market was predicted to shift significantly. However, issues such as mercury release during calcining need to be resolved.[30]
Because up to 12% of drywall is wasted during the manufacturing and installation processes and the drywall material is frequently not reused, disposal can become a problem. Some landfill sites have banned the dumping of drywall. Some manufacturers take back waste wallboard from construction sites and recycle them into new wallboard. Recycled paper is typically used during manufacturing. More recently, recycling at the construction site itself has been researched. There is potential for using crushed drywall to amend certain soils at building sites, such as sodic clay and silt mixtures (bay mud), as well as using it in compost.[36] As of 2016, industry standards are being developed to ensure that when and if wallboard is taken back for recycling, quality and composition are maintained. 2ff7e9595c
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