Drywall is a sheet of gypsum (also known as wallboard), with or without additives, that is extruded between thick sheets of paper and plaster.
As a labor- and time-efficient substitute for lath and plaster, drywall building gained popularity in North America in the middle of the 20th century. [3]
A Brief History of Drywall
In Rochester, Kent, a plasterboard factory initially opened its doors in 1888. Rensselaer Polytechnic Institute alums Augustine Sackett and Fred Kane invented the Sackett Board in 1894. It was made by stacking four layers of wool felt paper with plaster. The sheets had open (untaped) edges and measured 36 by 36 by 1/4 inch (914 mm × 914 mm × 6 mm) in thickness.
Between 1910 and 1930, the two inner layers of felt paper were removed in favor of paper-based facings, and gypsum board evolved. After acquiring Sackett Plaster Board Company in 1910, United States Gypsum Corporation introduced Sheetrock in 1917. [5] In addition to offering installation efficiency, Sheetrock was also developed as a fire resistant indicator. Gypsum lath was an early plaster substrate. Later air entrainment technology made boards lighter and less brittle. Joint treatment materials and procedures also evolved. A panel made of compressed gypsum plaster board that occasionally had holes or grooves drilled into it to allow wet plaster to key into its surface was an alternative to conventional wood or metal lath. In 1936, US Gypsum registered the trademark ROCKLATH [7] for their gypsum lath product. As it evolved, it was faced with paper impregnated with gypsum crystals that bonded with the applied facing layer of plaster.
The businesses Lafarge, BPB, Knauf, and Gyproc Benelux were hit with fines totaling €420 million by the European Commission for operating a cartel on the market that impacted 80% of customers in France, the UK, Germany, and the Benelux nations.
Production
In manufacturing drywall (also known as plasterboard), a wallboard panel is made up of two layers of paper and a layer of gypsum plaster. After heating the raw gypsum (CaSO4·2H2O) to remove water, it is partially rehydrated to yield the calcium sulfate hemihydrate (CaSO4·1/2H2O). The board is then formed by sandwiching a core of the wet mixture between two sheets of heavy paper or water glass sheets. The board is then mixed with additives that may increase mildew and fire resistance, lower water absorption (wax emulsion or silanes), and reduce creep. The sandwich gets stiff and sturdy enough to be used as construction material once the center solidifies and is dried in a sizable drying chamber.
Natural gas is typically used in drying rooms nowadays. It takes between 1,750,000 and 2,490,000 BTU (1.85–2.63 GJ) to dry 1,000 square feet (93 m2) of wallboard. Scrubbers are devices used in coal-fired power stations to remove sulfur from exhaust emissions. They also reduce water content, which in turn shortens the drying time. Organic dispersants and plasticizers are employed to ensure that the slurry flows during manufacture. Through a process known as flue-gas desulfurization (FGD), the sulfur is absorbed by powdered limestone and multiple new compounds are produced. “FGD gypsum” is the name of one. In the US and other countries, drywall construction frequently uses this.[11][12]
Around the world, 8.4 billion square meters of drywall were sold in 2020.
Specifications
New Zealand and Australia
In Australia and New Zealand, plaster board is utilized. The product is commonly referred to as Gyprock in Australia, which is the name of the biggest plaster board manufacturer.[14] In New Zealand, it is also called Gibraltar and Gib board,[15] genericized from the registered trademark (“GIB”) of the locally made product that dominates the local market.[16][17] A specific type of Gibraltar board for use in wet conditions (such as bathrooms and kitchens) is known as AquaGib.
It can occasionally be found in thicknesses as high as 25 mm. It is made in thicknesses of 10 mm, 13 mm, and 16 mm. Panels are often sold in sheets that are 1200 mm wide and may be 1800, 2400, 3000, 4800, or 6000 mm in length. Typically, sheets are fastened to cold-formed steel or wood frames at intervals of 150–300 mm along the beam and 400–600 mm across members.[18]
When rebuilding buildings from the 19th and early 20th centuries, plasterboard has supplanted scrim and sarking walls in both countries generally.
America and Canada together
In order to fit different applications, drywall panels are made in Canada and the United States in widths of 48, 54, and 96 inches (1.2, 1.4, and 2.4 meters). They are also available in different lengths. The most common width is 48 inches, although as 9 feet (2.7 meters) ceiling heights grow more common, 54-inch-wide panels are starting to gain popularity. Although lengths of up to 16 feet (4.9 m) are typical, 8 feet (2.4 m) is the most common. The most common thicknesses are 1⁄2 and 5⁄8 inches (13 and 16 mm); for particular uses, thicknesses of 1⁄4, 3⁄8, 3⁄4, and 1 inch (6.4, 9.5, 19.1, and 25.4 mm) are utilized. Gyproc is a common term for drywall in various parts of Canada.
Europe
The majority of plaster board made in Europe is 120 centimetres (47 in) wide; sheets 60 and 90 centimetres (24 and 35 in) wide are also produced. Plaster board 120 mm (47 in) wide is typically only made in 240 mm (94 in) lengths; sheets of 250, 260, 270, 280, and 300 mm (98, 102, 106, 110, and 118 in) and longer are also routinely made. The thicknesses of plaster board range from 9.5 to 25 millimeters (3/8 to 1 in).[19]
Plaster board is only made with one of three edge treatments: tapered edge, where the long edges of the board are tapered with a mm bevel at the front to allow jointing materials to be finished flush with the main board face; plain edge, where the entire surface will receive a thin coating (skim coat) of finishing plaster; and beveled on all four sides, used in roofing products. Four-sided chamfered drywall for ordinary use is not offered by major UK manufacturers.
Construction Methods
A full house may be drywalled in one or two days by two skilled drywallers instead of requiring a week to apply plaster, and drywall is simple enough to be put by many do-it-yourself home carpenters. Drywall can be finished anywhere from a level 0 to a level 5, where 0 is not finished in any fashion and 5 is the most pristine. [21] Depending on how important the finish is to the customer, the extra steps in the finish may or may not be necessary, though priming and painting of drywall is recommended in any location where it may be exposed to any wear. The work of installing and finishing drywall in large-scale commercial construction is often split between drywall mechanics, or hangers, who install the wallboard and tapers (also known as finishers, mud men, or float crew).
Using a utility knife to score the paper on the finished side (often white), break the sheet along the cut, and cut the paper backing are the steps involved in cutting drywall to size. Small features like light switch and outlet holes are typically cut with a tiny high-speed bit in a rotary tool, an oscillating multitool, or a keyhole saw. After that, drywall is fastened to the framework using adhesive, drywall screws, or nails.
Drywall fasteners, which are also called drywall clips or stops, are becoming more and more common in both residential and commercial building. Drywall fasteners have replaced the non-structural wood or metal blocking that was previously used to install drywall. They are used to reinforce interior drywall corners. Their use reduces labor and material costs, lessens truss uplift callbacks, boosts energy efficiency, and facilitates easier plumbing and electrical installation.
Diffuser screws countersink their heads slightly into the drywall when driven all the way home. Instead of using the traditional conical countersunk head, they utilize a concave taper called a “bugle head,” which compresses the drywall surface instead of cutting into it and prevents the paper from being torn. Light-gauge steel framing screws with carefully spaced threads and a sharp tip. Use self-drilling screws with precisely spaced holes if the steel framing weighs more than 20 gauge. Adhesives may be used in certain circumstances to secure the drywall to the wall.
The installer uses joint tape or fiber mesh to hide the seams between the drywall sheets once they have been fastened to the wall studs or ceiling joists. Typically, drywall trowels and knives are used to distribute layers of joint compound, also known as mud. Applying this compound to any flaws or screw holes is also recommended. Prior to painting, the compound is typically let to air dry and then smoothed. To reduce the apparent contrast between the paper and mudded regions after painting, the entire wall may be given a skim coat, a thin layer (approximately 1 mm or 1 32 in) of finishing compound.
Veneer plastering is another kind of similar skim coating, however it’s done a little thicker (approximately 2 mm or 3⁄32 in). For veneering, a somewhat different specialized setting compound called “finish plaster” with gypsum and lime putty is used. Blueboard, which has paper that has been specifically treated, is used in this application to hasten the setting of the gypsum plaster component. It just takes one layer since this setting shrinks significantly less than the air-dry compounds typically used in drywall. Moreover, drywall boards have tapered edges, whereas blueboard has square edges. While the tape in veneer plastering is buried beneath a flat surface, the tape in taped jointing is countersunk using tapered drywall boards. An intermediary stylistic step between full multi-coat “wet” plaster and the limited joint-treatment-only “dry” wall is one coat veneer plaster over dry board.
Sound Control
Sound transmission through walls and ceilings can be decreased by the kind and installation method of drywall. The construction details of the framing with steel studs, wider stud spacing, double studding, insulation, and other details reducing sound transmission are also crucial. Several builders’ books claim that thicker drywall reduces sound transmission, but engineering manuals recommend using multiple layers of drywall, sometimes of different thicknesses and glued together, or specialty types of drywall designed to reduce noise. With resilient channels on one side and glass wool batt insulation between the studs, a wood stud wall with double 1-1/2-inch (13 mm) of drywall on both sides can raise its Sound Transmission Class (STC) ratings from 33 for a standard stud wall to as high as 59.[23]
Regular 5/8-inch (16 mm) panels (with or without light-gauge resilient metal channels and/or insulation) may be used to slightly reduce sound transmission, but using two layers of drywall—sometimes in conjunction with other elements—or specifically made, sound-resistant drywall is more effective.
Mold Growth and Water Damage
Because of the intrinsic characteristics of the elements that make up drywall, which include gypsum, paper, and organic additives and binders, drywall is extremely susceptible to moisture. Gypsum will soften when exposed to moisture and eventually become a sticky paste when submerged for an extended period of time, like during a flood. A building’s entire drywall may need to be taken down and replaced after one of these instances. The paper facings and organic additives mixed with the gypsum core also serve as food for mold.
Water can quickly enter the core of the board by capillary action, where mold can form inside, thanks to the porosity of the board, which was added during production to reduce the board’s weight and minimize building time and costs. Because of the saturation of the grooves directly behind the tape where the drywall pieces meet, water that enters a room from overhead may cause ceiling drywall tape to split from the ceiling. Additionally, the drywall may begin to soften around the screws that hold it in place. The weight of the water may also cause the drywall to sag and finally collapse, necessitating replacement.
Termites can consume the paper facings on drywall if they infest a wall cavity covered in drywall. As a result, the painted surface starts to crumble and eat away at the paper backing. If enough of the paper has been eaten, the gypsum core can easily crack or crumble without it, necessitating not only repainting and patching the damaged surface but also removing and replacing the drywall.
Professional restoration specialists can often avoid the expense, trouble, and challenge of removing and replacing the damaged drywall, particularly in cases where the drywall has been exposed to water or moisture for less than 48 hours. They employ quick drying methods that restore most or all of the drywall while getting rid of the components needed to encourage microbial activity.
For these reasons, areas that are predicted to have high humidity, such as kitchens, bathrooms, and laundry rooms, should preferably employ cement board and greenboard, a type of drywall with an exterior face that is wax- and/or chemically coated to resist mold growth[25].
Additional Damage
When honeybees are setting up a stray nest in a building and want to expand their nest area, they are able to readily chew through foam insulation and the gypsum portion of sheetrock.
Diseases and corrosion problems with high sulfur drywall
A significant quantity of damaged drywall was brought into the country from China and installed in tens of thousands of homes during Hurricane Katrina reconstruction efforts in 2006 and 2007, among other locations. The building’s unpleasant stench, health consequences, and metal corrosion were among the grievances. This is brought on by sulfurous gas emissions. Although US homes are constructed far more tightly and have less airflow than Chinese homes, the same drywall was sold in Asia without any issues. Emissions from the imported drywall have been found to include volatile sulfur compounds, such as hydrogen sulfide, which may be related to health issues. A wide variety of drywall types release these substances into the air.
Many of the drywall sheets are merely marked “Made in China,” making it challenging to identify the manufacturer, despite the fact that numerous lawsuits are underway in numerous jurisdictions. In November 2009, the Consumer Product Safety Commission (CPSC) revealed a “strong association” between Chinese drywall and corrosion of pipes and wires reported by thousands of American homeowners. The investigation was underway at the time [27]. All drywall must now be tested for volatile sulfur, and any with more than ten parts per million (ppm) cannot be sold in the United States. The problem was resolved in 2011.
Fire Resistance
Drywall Type X
As a passive fire protection measure, Type X drywall is used in the construction of certain fire barrier walls. The water of crystallization is bonded in hydrate form in gypsum. This water vaporizes when exposed to heat or fire, delaying heat transfer until the gypsum’s water content is reached. The Canadian Building Code, DIN 4102 Part 4, Underwriters Laboratories, and Underwriters Laboratories of Canada (ULC) are among the design or certification listing catalogues that document fire-rated assemblies constructed of drywall. 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.
Designs that pass tests are identified by the code and given a fire resistance rating. The final designs are included into the code and are available for usage by any manufacturer. However, if the material used in the field configuration can be shown to meet the minimal requirements of Type X drywall and if enough layers and thicknesses are used, individual manufacturers may also have proprietary designs that they have had independently tested and approved.
Type C drywall
The core of Type C gypsum panels has a higher density of glass fibers, giving them stronger fire resistance than Type X. Additionally, vermiculite, which expands when exposed to high fire temperatures, serves as a shrinkage-compensating addition in the core of Type C panels. The Type C panels’ cores are able to maintain their dimensional stability throughout a fire because this expansion takes place at a temperature that is similar to that at which the gypsum in the core is calcined.
United States Market
With a total wallboard plant capacity of 42 billion square feet (3.9 billion square meters) annually, North America is one of the world’s largest users of gypsum board. This is approximately half of the global annual production capacity of 85 billion square feet (7.9 billion square meters). Since “an average new American home contains more than 7.31 metric tons of gypsum,”[31] the gypsum board sector was one of the major beneficiaries of the building boom.
The United States Environmental Protection Agency introduced the Clean Air Interstate Rule in March 2005, which mandates that fossil-fuel power plants “cut sulfur dioxide emissions by 73%” by the year 2018[32]. In addition, the Clean Air Interstate Rule asks the power plants to install new scrubbers, or industrial pollution control devices, to remove sulfur dioxide from the output waste gas. Flue-gas desulfurization (FGD) is a process used by scrubbers that yields synthetic gypsum as a useful byproduct. It was anticipated that the market for gypsum board would change dramatically in reaction to the new availability of this raw material. But problems like mercury leakage during calcining must be resolved.
Varieties offered in the US and Canada
Standard white board, ranging in thickness from 1/64 to 3/64 inch (6.3 to 19 mm).
Based on how long a particular wall assembly can sustain a typical fire test, fire-resistant (“Type X”), various thicknesses, and numerous layers of wallboard provide enhanced fire ratings. To increase fire resistance, perlite, vermiculite, and boric acid are frequently used.
Moisture resistance is provided by greenboard, drywall that has an oil-based additive in the green paper covering. Bathrooms and other places where high humidity is predicted are common places to utilize it [34].
Blueboard, or blue face paper, provides mold and water resistance by forming a strong bond with a skim coat or built-up plaster finish.
Cement board can be used as a base for ceramic tile and in showers or sauna rooms since it is more water-resistant than greenboard.
To improve sound transmission quality, sound board is made from wood fibers.
In order to dramatically raise the sound transmission class rating, soundproof drywall is a layered drywall made with gypsum and other components like dampening polymers.
Drywall without paper that is mold-resistant and has a fiber glass face[35]
Boards made from repurposed agricultural resources are called Enviroboards.
drywall that has been lead-lined is utilized around radioactive equipment.[36]
Vapor barrier made of drywall backed with foil [37]
Controlled density (also known as ceiling board), is much stiffer than a standard whiteboard and is only available in a thickness of 1/2 inch (13 mm).
EcoRock is a drywall that is touted as being ecologically beneficial since it uses an energy-efficient technique and a combination of 20 ingredients, including recycled fly ash, slag, kiln dust, and fillers, without using starch cellulose.
“Firecode C” Gypsum. With the exception of additional glass fibers and a form of vermiculite used to lessen shrinking, this board is comparable to Type X in composition. The gypsum core becomes less pliable in a fire and stays in place even after the gypsum dries out because this addition expands at a similar rate as the gypsum shrinks when exposed to intense heat.
tag: # drywall – definitive guide
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