Difference between revisions of "Drywall" - New World Encyclopedia

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:''"Sheetrock" redirects here.''
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[[Image:Drywall.jpg|thumb|300px|Example of drywall, the common interior building material, with [[joint compound]].]]
  
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:''For the musical group "Drywall," see [[Drywall (musical project)]]''
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'''Drywall''' is a common manufactured [[building material]] used globally for the finish construction of interior walls and ceilings. Each panel of drywall is made of a [[paper]] liner wrapped around an inner core made primarily from [[gypsum]] [[plaster]], the semi-[[hydrous]] form of [[calcium sulfate]] (CaSO<sub>4</sub>.½ H<sub>2</sub>O).
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{{toc}}
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The use of drywall offers the advantages of speed in construction and relative affordability. North America is one of the largest gypsum board users in the world, and the gypsum board market is one of the biggest beneficiaries when there is a housing boom.
  
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[[Image:Drywall.jpg|thumb|Example of drywall with [[joint compound]], the common interior building material. (This photo shows drywall hung vertically.)]]
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== Alternative names ==
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Drywall is also commonly known as '''gypsum board,''' '''wallboard,''' '''plasterboard''' (U.S., UK, Ireland, Australia), '''Gibraltar board''' or '''gib''' (New Zealand—GIB being a trademark of Winstone Wallboards), '''rock lath,''' '''Sheetrock''' (a trademark of [[USG Corporation|United States Gypsum Company]]), '''gyproc''' (Canada, Australia, UK), '''pladur''' (Spain—after the Pladur brand), or '''rigips''' (Germany and Central Europe—after the Rigips brand), or simply '''board.'''
  
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'''Drywall''' is a common manufactured [[building material]] used globally for the finish construction of interior walls and ceilings.
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== Preparation of drywall ==
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Raw gypsum must be [[calcination|calcined]] before use. Flash calciners typically use natural gas today. The plaster is mixed with fiber (typically paper and/or [[fiberglass]]), [[plasticizer]], [[foaming agent]], [[potash]] as an accelerator, [[EDTA]] or other [[chelate]] as a retarder, various additives that increase [[mildew]] and fire resistance (fiberglass or [[vermiculite]]), and water. This is then formed by sandwiching a core of wet gypsum between two sheets of heavy paper or fiberglass mats. When the core sets and is dried in a large drying chamber, the sandwich becomes rigid and strong enough for use as a building material. Drying chambers typically use natural gas today. Depending on plant efficiency and energy costs, 25-45 percent of drywall cost today is related to energy, primarily natural gas.
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A drywall panel is made of a [[paper]] liner wrapped around an inner core made primarily from [[gypsum]] [[plaster]], the semi-[[hydrous]] form of [[calcium sulfate]] (CaSO<sub>4</sub>.½ H<sub>2</sub>O).  The raw gypsum (mined or [[FGD]]) must be [[calcination|calcined]] before use. Flash calciners typically use natural gas today. The plaster is mixed with fiber (typically paper and/or [[fiberglass]]), [[plasticizer]], [[foaming agent]], [[potash]] as an accelerator, [[EDTA]] or other [[chelate]] as a retarder, various additives that increase [[mildew]] and fire resistance (fiberglass or [[vermiculite]]), and water. This is then formed by sandwiching a core of wet gypsum between two sheets of heavy paper or fiberglass mats. When the core sets and is dried in a large drying chamber, the sandwich becomes rigid and strong enough for use as a building material. Drying chambers typically use natural gas today. Depending on plant efficiency and energy costs, 25% to 45% of drywall cost today is related to energy, primarily natural gas.{{Fact|date=April 2008}}
 
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Drywall is also commonly known as '''gypsum board''', '''wallboard''', '''plasterboard''' (USA,UK, Ireland, Australia), '''Gibraltar board''' or '''gib''' (New Zealand - GIB being a trademark of Winstone Wallboards), '''rock lath''', '''Sheetrock''' (a trademark of [[USG Corporation|United States Gypsum Company]]),<ref>{{cite news|title=Trademarks|publisher=United States Gypsum Company|url=http://www.usg.com/about/trademarks/trademarks_united.jsp|accessdate=2006-10-19}}</ref> '''gyproc''' (Canada, Australia, UK), '''pladur''' (Spain - after the Pladur brand), or '''rigips''' (Germany and Central Europe - after the Rigips brand), or simply '''board'''.
 
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== Specifications (USA and Canada) ==
 
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Drywall is typically available in 4&nbsp;ft (1219&nbsp;mm) wide sheets of various lengths. With the rising popularity of {{convert|9|ft|m|abbr=on}} high ceilings in new home construction, 4.5&nbsp;ft (1372&nbsp;mm) wide panels have become commonly available as well. Newly formed sheets are cut from a belt, the result of a continuous manufacturing process. In some commercial applications, sheets up to {{convert|16|ft|m|abbr=on}} are used. Larger sheets make for faster installation, since they reduce the number of joints that must be finished. Often, a sizable quantity of any custom length may be ordered, from factories, to exactly fit ceiling-to-floor on a large project.
 
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The most commonly used drywall is one-half-inch thick but can range from one quarter (6.35&nbsp;mm) to one inch (25.4&nbsp;mm).  For soundproofing or fire resistance, two layers of drywall are sometimes laid at right angles to each other.  In North America, five-eighths-inch-thick drywall with a one-hour fire-resistance rating is often used where fire resistance is desired.
 
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Drywall provides a thermal resistance [[R-value (insulation)|R-value]] of 0.32 for three-eighths-inch board, 0.45 for half inch, 0.56 for five-eighths inch and 0.83 for one-inch board.  In addition to increased R-value, thicker drywall has a higher [[sound transmission class]].
 
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== Specifications (UK) ==
 
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In the UK, plasterboard is typically manufactured in metric sizes, with the common sizes being corrolaries of old imperial sizes.
 
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Most plasterboard is made in 1200&nbsp;mm wide sheets, though 900&nbsp;mm wide sheets are also made. 1200&nbsp;mm wide plasterboard is most commonly made in 2400&nbsp;mm lengths, though 2700&nbsp;mm and 3000&nbsp;mm length sheets are also commonly available.
 
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The most commonly used thicknesses of plasterboard available are 12.5&nbsp;mm (modern equivalent of half an inch), typically used for walls, and 9.5&nbsp;mm (modern equivalent of three-eights of an inch), typically used for ceilings. 15&nbsp;mm thick board is commonly available, and other thicknesses are also produced.
 
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Plasterboard is commonly made with one of two different edge treatments: Tapered Edge, where the sides of the board are tapered at the front to allow for jointing materials to be finished flush with the main board face, and Straight Edge, where there is no different thickness at the side of the board.
 
  
 
== Construction techniques ==
 
== Construction techniques ==
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[[Image:Drywall material handler.jpg|thumb|left|Drywall is delivered to a building site on a flatbed truck and unloaded with a forked material handler crane. The bulk drywall sheets are unloaded directly to upper floors via a window or exterior doorway.]]
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[[Image:Drywall material handler.jpg|thumb|left|Drywall is delivered to a building site on a flatbed truck and unloaded with a forked material handler crane. The bulk drywall sheets are unloaded directly to upper floors via a window or exterior doorway.]]  
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As opposed to a week-long [[plaster]] application, an entire house can be drywalled in one or two days by two experienced [[Drywall mechanic|drywallers]], and drywall is easy enough to use that it can be installed by many amateur home carpenters.  In large-scale commercial construction, the work of installing and finishing drywall is often split between the [[drywall mechanic]]s, or ''hangers'', who install the wallboard, and the ''tapers'' and ''mudmen'', or ''float crew'', who finish the joints and cover the nailheads with [[drywall compound]].
 
  
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Drywall is cut to size, using a large [[T-square]], by scoring the paper on the front side (usually white) with a [[utility knife]], breaking the sheet along the cut, scoring the paper backing, and finally breaking the sheet in the opposite direction. Small features such as holes for outlets and light switches are usually cut using a [[keyhole saw]] or a small high-speed bit in a rotary tool. Drywall is then fixed to the [[wall]] structure with [[nail (engineering)|nails]], or more commonly in recent years, the now-ubiquitous ''drywall [[screw]]s''.
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As opposed to a week-long [[plaster]] application, an entire house can be drywalled in one or two days by two experienced [[drywall mechanic]]s ''(drywallers)'' and drywall is easy enough to use that it can be installed by many amateur home carpenters. In large-scale commercial construction, the work of installing and finishing drywall is often split between the drywall mechanics, or ''hangers,'' who install the wallboard, and the ''tapers'' and ''mudmen,'' or ''float crew,'' who finish the joints and cover the nail heads with [[drywall compound]].
  
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[[Drywall fasteners]], also referred to as drywall clips or stops, are gaining popularity in both residential and commercial construction. Drywall fasteners are used for supporting interior drywall corners and replacing the non-structural wood or metal blocking that traditionally was used to install drywall. Their function serves to save on material and labor expenses; to minimize call backs due to truss uplift; to increase energy efficiency; and to make plumbing and electrical installation simpler.  Many green building and energy efficiency models suggest using drywall fasteners to conserve resources and save energy, including the U.S. Dept. of Energy.
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Drywall is cut to size, using a large [[T-square]], by scoring the paper on the front side (usually white) with a [[utility knife]], breaking the sheet along the cut, scoring the paper backing, and finally breaking the sheet in the opposite direction. Small features such as holes for outlets and light switches are usually cut using a [[keyhole saw]] or a small high-speed bit in a rotary tool. Drywall is then fixed to the [[wall]] structure with [[nail (engineering)|nails]], or more commonly in recent years, the now-ubiquitous ''drywall [[screw]]s''.
  
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[[Image:Drywall-screws-v1.png|thumb|100px|right|Drywall screws are designed to be self-tapping.]]
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[[Drywall fastener]]s, also referred to as drywall clips or stops, are gaining popularity in both residential and commercial construction. Drywall fasteners are used for supporting interior drywall corners and replacing the non-structural wood or metal blocking that traditionally was used to install drywall. Their function serves to save on material and labor expenses; to minimize call backs due to truss uplift; to increase energy efficiency; and to make plumbing and electrical installation simpler. Many green building and energy efficiency models suggest using drywall fasteners to conserve resources and save energy, including the U.S. Dept. of Energy.
  
 
Drywall screws have a curved, bugle-shaped top, allowing them to self-pilot and install rapidly without punching through the paper cover. These screws are set slightly into the drywall. When drywall is hung on [[Light frame construction|wood framing]], screws having an acute point and widely spaced threads are used. When drywall is hung on light-gauge steel framing, screws having an acute point and finely spaced threads are used. If the steel framing is heavier than 20-gauge, [[self-tapping]] screws with finely spaced threads must be used. In some applications, the drywall may be attached to the wall with [[adhesive]]s.  
 
Drywall screws have a curved, bugle-shaped top, allowing them to self-pilot and install rapidly without punching through the paper cover. These screws are set slightly into the drywall. When drywall is hung on [[Light frame construction|wood framing]], screws having an acute point and widely spaced threads are used. When drywall is hung on light-gauge steel framing, screws having an acute point and finely spaced threads are used. If the steel framing is heavier than 20-gauge, [[self-tapping]] screws with finely spaced threads must be used. In some applications, the drywall may be attached to the wall with [[adhesive]]s.  
  
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[[Image:Screwgun.jpg|right|thumb|Electric screw gun used to drive drywall screws]]
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[[Image:Screwgun.jpg|right|thumb|Electric screw gun used to drive drywall screws.]]
  
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After the sheets are secured to the [[Platform framing|wall studs]] or ceiling [[joist]]s, the seams between drywall sheets are concealed using joint tape and several layers of [[joint compound]] (sometimes called "mud"). This compound is also applied to any screw holes or defects. The compound is allowed to air dry then typically sanded smooth before painting. Alternatively, for a better finish, the entire wall may be given a ''skim coat'', a thin layer (about 1&nbsp;mm or 1/16&nbsp;inch) of finishing compound, to minimize the visual differences between the paper and mudded areas after painting.
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After the sheets are secured to the [[Platform framing|wall studs]] or ceiling [[joist]]s, the seams between drywall sheets are concealed using joint tape and several layers of [[joint compound]] (sometimes called "mud"). This compound is also applied to any screw holes or defects. The compound is allowed to air dry then typically sanded smooth before painting. Alternatively, for a better finish, the entire wall may be given a ''skim coat,'' a thin layer (about 1&nbsp;mm or 1/16&nbsp;inch) of finishing compound, to minimize the visual differences between the paper and mudded areas after painting.
  
 
Another similar skim coating is always done in a process called veneer plastering, although it is done slightly thicker (about 2&nbsp;mm or 1/8&nbsp;inch). Veneering uses a slightly different specialized setting compound ("finish plaster") that contains [[gypsum]] and lime [[putty]]. For this application blueboard is used which has special treated paper to accelerate the setting of the gypsum plaster component. This setting has far less shrinkage than the air-dry compounds normally used in drywall, so it only requires one coat. Blueboard also has square edges rather than the tapered-edge drywall boards. The tapered drywall boards are used to countersink the tape in taped jointing whereas the tape in veneer plastering is buried beneath a level surface. One coat veneer plaster over dry board is an intermediate style step between full multi-coat "wet" plaster and the limited joint-treatment-only given "dry" wall.
 
Another similar skim coating is always done in a process called veneer plastering, although it is done slightly thicker (about 2&nbsp;mm or 1/8&nbsp;inch). Veneering uses a slightly different specialized setting compound ("finish plaster") that contains [[gypsum]] and lime [[putty]]. For this application blueboard is used which has special treated paper to accelerate the setting of the gypsum plaster component. This setting has far less shrinkage than the air-dry compounds normally used in drywall, so it only requires one coat. Blueboard also has square edges rather than the tapered-edge drywall boards. The tapered drywall boards are used to countersink the tape in taped jointing whereas the tape in veneer plastering is buried beneath a level surface. One coat veneer plaster over dry board is an intermediate style step between full multi-coat "wet" plaster and the limited joint-treatment-only given "dry" wall.
  
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== Fire resistance ==
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=== Common drywall tools ===
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When used as a component in fire barriers, drywall is a [[passive fire protection]] item. In its natural state, gypsum contains the [[water]] of crystallisation bound in the form of [[hydrate]]s. When exposed to [[heat]] or [[fire]], this water is vapourised, retarding heat transfer. Therefore, a fire in one room that is separated from an adjacent room by a fire-resistance rated drywall assembly, will not cause this adjacent room to get any warmer than the boiling point (100°C) until the water in the gypsum is gone. This makes '''drywall''' an [[Ablation|ablative]] material because as the hydrates sublime, a crumbly dust is left behind, which, along with the paper, is sacrificial. Generally, the more layers of Type X drywall one adds, the more one increases the fire-resistance of the assembly, be it horizontal or vertical. Evidence of this can be found both in publicly available design catalogues on the topic, as well as common certification listings. "Type X" drywall is formulated by adding glass fibers to the gypsum, to increase the resistance to fires, especially once the hydrates are spent, which leaves the gypsum in powder form. Type X is typically the material chosen to construct walls and ceilings that are required to have a fire-resistance rating.
 
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<gallery>
 
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Image:Drywall_firestop_problem1.jpg|A typical [[passive fire protection|fire]] problem:  the measures taken by the plumbers and the drywallers are at cross-purposes.
 
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Image:Drywall_firestop_problem2.jpg|Another example: this [[steel]] [[Sleeve (construction)|sleeve]], a [[penetrant]] itself, causes more problems than it solves.
 
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Image:Drywall_firestop_problem3.jpg|[[Penetrant]]s have been punched and burned through drywall, compromising its integrity.
 
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Image:Drywall_shaft_damage.jpg|Mechanical shaft with compromised fire-resistance rating through pipe installation.
 
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Image:Drywall_firestop_problem4.jpg|Finished, painted, fire-resistance rated drywall assembly. A common [[deficiency]]: Lift ceiling tiles and find electrical and mechanical service penetrations without a firestop.
 
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Image:Drywall_reality.jpg|Improper drywall and absent [[firestop]]s at [[Cambrian College]], [[Greater Sudbury]], [[Ontario]], [[Canada]].
 
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Image:How_cambrian_college.jpg|Improper [[Firestop]] and [[Fireproofing]] interface, August 2000, [[Cambrian College]], [[Greater Sudbury]], [[Ontario]], [[Canada]].
 
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Image:Cambrian_college_no_firestop_1.jpg|Improper breach of fire-resistance rated drywall assembly, August 2000, [[Cambrian College]], [[Greater Sudbury]], [[Ontario]], [[Canada]].
 
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Image:Nortown_plastic_pipe_drywall.jpg|The "I-was-there-first-scenario", resulting in improper drywall firestops with plastic [[piping]].
 
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</gallery>
 
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Fire testing of drywall assemblies for the purpose of expanding national catalogues, such as the [[National Building Code of Canada]], [[Germany]]'s Part 4 of DIN4102 and its British cousin BS476, are a matter of routine [[research and development]] work in more than one nation and can be sponsored jointly by national authorities and representatives of the drywall industry. For example, the [[National Research Council of Canada]] routinely publishes [http://irc.nrc-cnrc.gc.ca/pubs/fulltext/nrcc41733/nrcc41733.pdf such findings]. The results are printed as approved designs in the back of the building code. Generally, exposure of drywall on a panel furnace removes the water and calcines the exposed drywall and also heats the studs and [[fastener]]s holding the drywall. This typically results in [[deflection]] of the assembly towards the fire, as that is the location where the [[Sublimation (chemistry)|sublimation]] occurs, which weakens the assembly, due to the fire influence. When tests are co-sponsored, resulting in code recognised designs with assigned fire-resistance ratings, the resulting designs become part of the code and are not limited to use by any one manufacturer, provided the material used in the field configuration can be demonstrated to meet the minimum requirements of Type X drywall (such as an entry in the appropriate category of the [[Underwriters Laboratories|UL]] Building Materials Directory) and that sufficient layers and thicknesses are used. [[Fire test]] reports for such unique third party tests are confidential. Deflection of drywall assemblies is important to consider to maintain the integrity of drywall assemblies in order to preserve their ratings. The deflection of drywall assemblies can vary somewhat from one test to another. Importantly, [[penetrant]]s do not follow the deflection movement of the drywall assemblies they penetrate. For example, see [[cable tray]] movement in a [http://en.wikipedia.org/wiki/Image:Tray_cross_barrier.jpg German test]. It is, therefore, important to test [[firestop]]s in full scale wall panel tests, so that the deflection of each applicable assembly can be taken into account. The size of the test wall assembly alone is not the only consideration for firestop tests. If the penetrants are mounted to and hung off the drywall assembly itself during the test, this does not constitute a realistic deflection exposure insofar as the firestop is concerned. In reality, on a construction site, penetrants are hung off the ceiling above. Penetrants may increase in length, push and pull as a result of operational temperature changes (e.g. hot and cold water in a [[pipe]]), particularly in a fire, but it is a physical impossibility to have the penetrants follow the movement of drywall assemblies that they penetrate, since they are not mounted to the drywalls in a building. It is, therefore, counterproductive to suspend penetrants from the drywall assembly during a fire test. As downward deflection of the drywall assembly and buckling towards the fire occurs, the top of the firestop is squeezed and the bottom of the firestop is pulled - and this is motion over and above that, which is caused by the expansion of metallic penetrants themselves, due to heat exposure in a fire. Both types of motion occur in reality because metal first expands in a fire and then softens once the critical temperature has been reached, as is explained under [[structural steel]]. To simulate the drywall deflection effect, one can simply mount the penetrants to the steel frame holding the test assembly. The operational and fire induced motion of the penetrants themselves, which is independent of the assemblies penetrated, can be separately arranged.
 
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== North American market ==
 
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North America hails as one of the largest gypsum board users in the world with a total wallboard plant capacity of 40 billion square feet per year.<ref>[http://minerals.usgs.gov/minerals/pubs/commodity/gypsum/gypsumcs06.pdf Mineral Commodity Summaries, January 2006]</ref> Moreover, the home building and remodeling markets in North America have increased demand the last five years. The gypsum board market is one of the biggest beneficiaries of the housing boom as "an average new American home contains more than 7.31 metric tons of gypsum."<ref>[http://minerals.usgs.gov/minerals/pubs/commodity/gypsum/gypsmyb01.pdf Donald W. Olson (2002) ''Gypsum''] History and production</ref>
 
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The introduction in March 2005 of the Clean Air Interstate Rule by the [[United States Environmental Protection Agency]] requires power plants to "cut sulfur dioxide emissions by 73%" by 2018.<ref>[http://www.epa.gov/cair/ Clean Air Interstate Rule]</ref>  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. <ref>[http://www.flyash.info/2003/75heeb.pdf Mercury Release from FGD Gypsum]</ref>
 
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===Waste===
 
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Because up to 17% of drywall is wasted during the manufacturing and installation processes,{{Fact|date=February 2007}}  and the drywall material is rarely re-used, disposal has become a problem. Some landfill sites have banned the dumping of drywall. Therefore, used drywall and gypsum are often dumped into the ocean where it may cause harm to sea life. The EPA regulates this ocean dumping by permit. Most manufacturers with an environmental concern take back the boards from construction sites, and burn them at high temperature to eliminate the paper and bring the gypsum back to its initial plaster state. Recycled paper is sometimes used during manufacturing. More recently, recycling at the construction site itself is being investigated. There is potential for using crushed drywall to amend certain soils at building sites, such as clay and silt mixtures ([[bay mud]]), as well as using it in compost. <ref>[http://www.ciwmb.ca.gov/Markets/StatusRpts/Inerts.htm Recycled Inerts]</ref> However, drywall that is composed of non-biodegradable or persistent toxic additives — including [[EDTA#Environmental_behavior|EDTA]], most plasticizers, and some mildew and fire retardants — presents a challenge, in that it cannot be safely returned to soil or reclaimed by industry without compromising human and environmental health.
 
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== Types available in the USA and Canada==
 
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* Regular white board, from 1/4" to 3/4" thickness
 
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* Fire-resistant ("Type X"), different thickness and multiple layers of wallboard provide increased fire rating based on the time a specific wall assembly can withstand a standardized fire test.  Often [[perlite]], [[vermiculite]] and [[boric acid]] are added to improve fire resistance.
 
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* Greenboard, the drywall that contains an oil-based additive in the green colored paper covering that provides moisture resistance. It is commonly used in washrooms and other areas expected to experience elevated levels of humidity.
 
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* Blueboard or gypsum base, the blue face paper forms a strong bond with a skim coat or a built-up plaster finish
 
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* Cement backerboard, which is more water-resistant than greenboard, for use in showers or sauna rooms, and as a base for ceramic tile
 
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* Soundboard is made from wood fibers to increase the [[Sound transmission class|sound rating]] (STC)
 
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* Soundproof drywall such as [[QuietRock]] is a laminated drywall made with gypsum, other materials, and damping polymers to significantly increase the STC
 
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* Mold-resistant, paperless drywall from [[Georgia-Pacific]]
 
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* [[Enviroboard]], a board made from recycled agricultural materials
 
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* Lead-lined drywall, a drywall used around radiological equipment
 
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* Foil-backed drywall to control moisture in a building or room
 
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== Common drywall tools ==
 
 
* [[Benches]]
 
* [[Benches]]
 
* [[Chalk line]]
 
* [[Chalk line]]
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* [[Utility knife]]
 
* [[Utility knife]]
  
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==Levels of Finish==
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==Levels of finish==
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"In 1990, four major trade associations, the Association of Wall and Ceiling Industries International (AWCI), the Ceilings and Interior Systems Construction Association (CISCA), the Gypsum Association (GA), and the Painting and Decorating Contractors of America (PDCA), presented the consensus document Levels of Gypsum Board Finish. The document was created to "precisely describe" the desired finish of walls and ceilings prior to final decoration. This precise description enables contractors to better understand the requirements of architects and building owners in order to enhance the satisfaction of the client. Specifications that include the Levels of Gypsum Board Finish also promote competitive bidding that allows the bidder to consider the correct labor and materials to finish the wall suitably for its final decoration." [http://www.nationalgypsum.com/resources/techtalk/revisiting.aspx]
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Reviewing industry standards for gypsum board finish, George Kutcher, Jr., opens with the following statement in ''Tech Talk'' of the National Gypsum Association:<ref>National Gypsum Company, [http://www.nationalgypsum.com/resources/techtalk/revisiting.aspx Tech Talk: Revisiting the Levels of Gypsum Board Finish.] Retrieved September 19, 2008.</ref>
  
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The official document (summarized below) is known as [http://www.nationalgypsum.com/literature/GA-214-96.pdf GA-214-96 "Recommended Levels of Gypsum Board Finish"].
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<blockquote>In 1990, four major trade associations, the Association of Wall and Ceiling Industries International (AWCI), the Ceilings and Interior Systems Construction Association (CISCA), the Gypsum Association (GA), and the Painting and Decorating Contractors of America (PDCA), presented the consensus document ''Levels of Gypsum Board Finish''. The document was created to "precisely describe" the desired finish of walls and ceilings prior to final decoration. This precise description enables contractors to better understand the requirements of architects and building owners in order to enhance the satisfaction of the client. Specifications that include the ''Levels of Gypsum Board Finish'' also promote competitive bidding that allows the bidder to consider the correct labor and materials to finish the wall suitably for its final decoration.</blockquote>
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The official document (summarized below) is known as "Recommended Levels of Gypsum Board Finish."<ref>AWCI, CISCA, GA, PDCA, [http://www.nationalgypsum.com/literature/GA-214-96.pdf GA-214-96, Recommended Levels of Gypsum Board Finish.] Retrieved September 19, 2008.</ref>
  
 
===Level 0===
 
===Level 0===
 
No taping, finishing, or accessories required.
 
No taping, finishing, or accessories required.
  
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'''Usage''': Temporary construction or when final decoration is undetermined.
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'''Usage:''' Temporary construction or when final decoration is undetermined.
  
 
===Level 1===
 
===Level 1===
 
All joints and interior angles shall have tape set in joint compound. Surface shall be free of excess joint compound. Tool marks and ridges are acceptable.
 
All joints and interior angles shall have tape set in joint compound. Surface shall be free of excess joint compound. Tool marks and ridges are acceptable.
  
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'''Usage''': Above false ceilings or other areas which are out of public view where a degree of fire and noise resistance is required.
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'''Usage:''' Above false ceilings or other areas which are out of public view where a degree of fire and noise resistance is required.
  
 
===Level 2===
 
===Level 2===
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All joints and interior angles shall have tape embedded in joint compound and wiped with a joint knife leaving a thin coating of joint compound over all joints and interior angles. Fastener heads and accessories shall be covered with a coat of joint compound. Surface shall be free of excess joint compound. Tool marks
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All joints and interior angles shall have tape embedded in joint compound and wiped with a joint knife leaving a thin coating of joint compound over all joints and interior angles. Fastener heads and accessories shall be covered with a coat of joint compound. Surface shall be free of excess joint compound. Tool marks and ridges are acceptable. Joint compound applied over the body of the tape at the time of tape embedment shall be considered a separate coat of joint compound and shall satisfy the conditions of this level.
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and ridges are acceptable. Joint compound applied over the body of the tape at the time of tape embedment
 
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shall be considered a separate coat of joint compound and shall satisfy the conditions of this level.
 
  
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'''Usage''': As a substrate for tile walls and ceilings as well as in garages, warehouses, and other places where appearance is not a primary concern.
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'''Usage:''' As a substrate for tile walls and ceilings as well as in garages, warehouses, and other places where appearance is not a primary concern.
  
 
===Level 3===
 
===Level 3===
 
All joints and interior angles shall have tape embedded in joint compound and one additional coat of joint compound applied over all joints and interior angles. Fastener heads and accessories shall be covered with two separate coats of joint compound. All joint compound shall be smooth and free of tool marks and ridges. It is recommended that the prepared surface be coated with a drywall primer prior to the application of final finishes.
 
All joints and interior angles shall have tape embedded in joint compound and one additional coat of joint compound applied over all joints and interior angles. Fastener heads and accessories shall be covered with two separate coats of joint compound. All joint compound shall be smooth and free of tool marks and ridges. It is recommended that the prepared surface be coated with a drywall primer prior to the application of final finishes.
  
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'''Usage''': Suitable base for heavy-medium textured paint or other thick finishes.
+
'''Usage:''' Suitable base for heavy-medium textured paint or other thick finishes.
  
 
===Level 4===
 
===Level 4===
 
All joints and interior angles shall have tape embedded in joint compound and two separate coats of joint compound applied over all flat joints and one separate coat of joint compound applied over interior angles. Fastener heads and accessories shall be covered with three separate coats of joint compound. All joint compound shall be smooth and free of tool marks and ridges. It is recommended that the prepared surface be coated with a drywall primer prior to the application of final finishes.
 
All joints and interior angles shall have tape embedded in joint compound and two separate coats of joint compound applied over all flat joints and one separate coat of joint compound applied over interior angles. Fastener heads and accessories shall be covered with three separate coats of joint compound. All joint compound shall be smooth and free of tool marks and ridges. It is recommended that the prepared surface be coated with a drywall primer prior to the application of final finishes.
  
−
'''Usage''': "Standard" household and office walls. Used with light or non-textured finishes. Not suitable for harsh lighting conditions which may highlight minor imperfections.
+
'''Usage:''' "Standard" household and office walls. Used with light or non-textured finishes. Not suitable for harsh lighting conditions which may highlight minor imperfections.
  
 
===Level 5===
 
===Level 5===
−
All joints and interior angles shall have tape embedded in joint compound and two separate coats of joint compound applied over all flat joints and one separate coat of joint compound applied over interior angles. Fastener heads and accessories shall be covered with three separate coats of joint compound. A thin skim coat of joint compound, or a material manufactured especially for this purpose, shall be applied to the entire surface. The surface shall be smooth and free of tool marks and ridges. It is recommended that the prepared surface be coated with a drywall primer prior to the application of finish paint.
+
All joints and interior angles shall have tape embedded in joint compound and two separate coats of joint compound applied over all flat joints and one separate coat of joint compound applied over interior angles. Fastener heads and accessories shall be covered with three separate coats of joint compound. A thin skim coat of joint compound, or a material manufactured especially for this purpose, shall be applied to the entire surface. The surface shall be smooth and free of tool marks and ridges. It is recommended that the prepared surface be coated with a drywall primer prior to the application of finish paint.
 +
 
 +
'''Usage:''' The skim coat is a final leveling agent suitable to smooth out a surface to be used under the harshest lighting conditions that may otherwise highlight any imperfections under the finished surface. This finish is highly recommended for gloss and entirely non-textured surfaces.
 +
 
 +
== Fire resistance ==
 +
When used as a component in fire barriers, drywall is a [[passive fire protection]] item. In its natural state, gypsum contains the [[water]] of crystallization bound in the form of [[hydrate]]s. When exposed to [[heat]] or [[fire]], this water is vaporized, retarding heat transfer. Therefore, a fire in one room that is separated from an adjacent room by a fire-resistance rated drywall assembly will prevent the adjacent room from getting any warmer than the boiling point of water (100°C), until the water in the gypsum is gone. This makes '''drywall''' an [[Ablation|ablative]] material because as the hydrates sublime, a crumbly dust is left behind, which, along with the paper, is sacrificial.
 +
 
 +
Generally, the more layers of "Type X" drywall one adds, the more one increases the fire-resistance of the assembly, be it horizontal or vertical. Evidence of this can be found both in publicly available design catalogues on the topic, as well as common certification listings. Type X drywall is formulated by adding glass fibers to the gypsum, to increase the resistance to fires, especially once the hydrates are spent, which leaves the gypsum in powder form. Type X is typically the material chosen to construct walls and ceilings that are required to have a fire-resistance rating.
 +
 
 +
Fire testing of drywall assemblies for the purpose of expanding national catalogs—such as the [[National Building Code of Canada]], [[Germany]]'s Part 4 of DIN4102 and its British cousin BS476—are a matter of routine [[research and development]] work in more than one nation and can be sponsored jointly by national authorities and representatives of the drywall industry. For example, the [[National Research Council of Canada]] routinely publishes such findings.<ref>V.R. Kodur and M.A. Sultan, [http://irc.nrc-cnrc.gc.ca/pubs/fulltext/nrcc41733/nrcc41733.pdf Performance of wood stud shear walls exposed to fire,] National Research Council of Canada. Retrieved September 19, 2008.</ref> The results are printed as approved designs in the back of the building code. Generally, exposure of drywall on a panel furnace removes the water and calcines the exposed drywall and also heats the studs and [[fastener]]s holding the drywall. This typically results in [[deflection]] of the assembly towards the fire, as that is the location where the [[Sublimation (chemistry)|sublimation]] occurs, which weakens the assembly, due to the fire influence.
 +
 
 +
<gallery>
 +
Image:Drywall_firestop_problem1.jpg|A typical [[passive fire protection|fire]] problem: The measures taken by the plumbers and the drywallers are at cross-purposes.
 +
Image:Drywall_firestop_problem2.jpg|Another example: This [[steel]] [[Sleeve (construction)|sleeve]], a [[penetrant]] itself, causes more problems than it solves.
 +
Image:Drywall_firestop_problem3.jpg|[[Penetrant]]s have been punched and burned through drywall, compromising its integrity.
 +
Image:Drywall_shaft_damage.jpg|Mechanical shaft with compromised fire-resistance rating through pipe installation.
 +
Image:Drywall_firestop_problem4.jpg|Finished, painted, fire-resistance rated drywall assembly. A common [[deficiency]]: Lift ceiling tiles and find electrical and mechanical service penetrations without a firestop.
 +
Image:Drywall_reality.jpg|Improper drywall and absent [[firestop]]s at [[Cambrian College]], [[Greater Sudbury]], [[Ontario]], [[Canada]].
 +
Image:How_cambrian_college.jpg|Improper [[Firestop]] and [[Fireproofing]] interface, August 2000, [[Cambrian College]], [[Greater Sudbury]], [[Ontario]], [[Canada]].
 +
Image:Cambrian_college_no_firestop_1.jpg|Improper breach of fire-resistance rated drywall assembly, August 2000, [[Cambrian College]], [[Greater Sudbury]], [[Ontario]], [[Canada]].
 +
Image:Nortown_plastic_pipe_drywall.jpg|The "I-was-there-first-scenario," resulting in improper drywall firestops with plastic [[piping]].
 +
</gallery>
 +
 
 +
== North American market ==
 +
North America hails as one of the largest gypsum board users in the world with a total wallboard plant capacity of 40 billion square feet per year.<ref>Mineral Commodity Summaries, [http://minerals.usgs.gov/minerals/pubs/commodity/gypsum/gypsumcs06.pdf Gypsum.] Retrieved September 6, 2008.</ref> Moreover, the home building and remodeling markets in North America have increased demand the last five years. The gypsum board market is one of the biggest beneficiaries of the housing boom as "an average new American home contains more than 7.31 metric tons of gypsum."<ref>Donald W. Olson, [http://minerals.usgs.gov/minerals/pubs/commodity/gypsum/gypsmyb01.pdf Gypsum,] USGS. Retrieved September 6, 2008.</ref>
  
−
'''Usage''': The skim coat is a final leveling agent suitable to smooth out a surface to be used under the harshest lighting conditions that may otherwise highlight any imperfections under the finished surface. This finish is highly recommended for gloss and entirely non-textured surfaces.
+
The introduction in March 2005, of the Clean Air Interstate Rule by the [[United States Environmental Protection Agency]] requires power plants to reduce sulfur dioxide emissions by 73 percent by 2018.<ref>Environmental Protection Agency, [http://www.epa.gov/cair/ Clean Air Interstate Rule.] Retrieved September 6, 2008.</ref> This rule also requested that 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.<ref>Loreal V. Heebink and David J. Hassett, [http://www.flyash.info/2003/75heeb.pdf Mercury Release from FGD Gypsum,] Flyash.info. Retrieved September 6, 2008.</ref>
 +
 
 +
== Specifications ==
 +
=== In the United States and Canada ===
 +
Drywall is typically available in 4&nbsp;ft (1219&nbsp;mm) wide sheets of various lengths. With the rising popularity of {{convert|9|ft|m|abbr=on}} high ceilings in new home construction, 4.5&nbsp;ft (1372&nbsp;mm) wide panels have become commonly available as well. Newly formed sheets are cut from a belt, the result of a continuous manufacturing process. In some commercial applications, sheets up to {{convert|16|ft|m|abbr=on}} are used. Larger sheets make for faster installation, since they reduce the number of joints that must be finished. Often, a sizable quantity of any custom length may be ordered, from factories, to exactly fit ceiling-to-floor on a large project.
 +
 
 +
The most commonly used drywall is one-half-inch thick but can range from one quarter (6.35&nbsp;mm) to one inch (25.4&nbsp;mm). For soundproofing or fire resistance, two layers of drywall are sometimes laid at right angles to each other. In North America, five-eighths-inch-thick drywall with a one-hour fire-resistance rating is often used where fire resistance is desired.
 +
 
 +
Drywall provides a thermal resistance [[R-value (insulation)|R-value]] of 0.32 for three-eighths-inch board, 0.45 for half inch, 0.56 for five-eighths inch and 0.83 for one-inch board. In addition to increased R-value, thicker drywall has a higher [[sound transmission class]].
 +
 
 +
=== In the United Kingdom ===
 +
In the UK, plasterboard is typically manufactured in metric sizes, with the common sizes being close to the earlier imperial sizes.
 +
 
 +
Most plasterboard is made in 1200&nbsp;mm wide sheets, though 900&nbsp;mm wide sheets are also made. 1200&nbsp;mm wide plasterboard is most commonly made in 2400&nbsp;mm lengths, though 2700&nbsp;mm and 3000&nbsp;mm length sheets are also commonly available.
 +
 
 +
The most commonly used thicknesses of plasterboard available are 12.5&nbsp;mm (modern equivalent of half an inch), typically used for walls, and 9.5&nbsp;mm (modern equivalent of three-eights of an inch), typically used for ceilings. 15&nbsp;mm thick board is commonly available, and other thicknesses are also produced.
 +
 
 +
Plasterboard is commonly made with one of two different edge treatments: Tapered Edge, where the sides of the board are tapered at the front to allow for jointing materials to be finished flush with the main board face, and Straight Edge, where there is no different thickness at the side of the board.
 +
 
 +
== Types available in the U.S. and Canada==
 +
* Regular white board, from 1/4" to 3/4" thickness
 +
* Fire-resistant ("Type X"), different thicknesses and multiple layers of wallboard provide increased fire rating based on the time a specific wall assembly can withstand a standardized fire test. Often [[perlite]], [[vermiculite]] and [[boric acid]] are added to improve fire resistance.
 +
* Greenboard, the drywall that contains an oil-based additive in the green colored paper covering that provides moisture resistance. It is commonly used in washrooms and other areas expected to experience elevated levels of humidity.
 +
* Blueboard or gypsum base, the blue face paper forms a strong bond with a skim coat or a built-up plaster finish
 +
* Cement backerboard, which is more water-resistant than greenboard, for use in showers or sauna rooms, and as a base for ceramic tile
 +
* Soundboard is made from wood fibers to increase the [[Sound transmission class|sound rating]] (STC)
 +
* Soundproof drywall such as [[QuietRock]] is a laminated drywall made with gypsum, other materials, and damping polymers to significantly increase the STC
 +
* Mold-resistant, paperless drywall from [[Georgia-Pacific]]
 +
* [[Enviroboard]], a board made from recycled agricultural materials
 +
* Lead-lined drywall, a drywall used around radiological equipment
 +
* Foil-backed drywall to control moisture in a building or room
 +
 
 +
== Handling waste ==
 +
Because up to 17 percent of drywall is wasted during the manufacturing and installation processes, and the drywall material is rarely re-used, disposal has become a problem. Some landfill sites have banned the dumping of drywall. Therefore, used drywall and gypsum are often dumped into the ocean where it may cause harm to sea life. The EPA regulates this ocean dumping by permit. Most manufacturers with an environmental concern take back the boards from construction sites, and burn them at high temperature to eliminate the paper and bring the gypsum back to its initial plaster state. Recycled paper is sometimes used during manufacturing.
 +
 
 +
More recently, recycling at the construction site itself is being investigated. There is potential for using crushed drywall to amend certain soils at building sites, such as clay and silt mixtures ([[bay mud]]), as well as using it in compost.<ref>California Integrated Waste Management Board, [http://www.ciwmb.ca.gov/Markets/StatusRpts/Inerts.htm Recycled Inerts.] Retrieved September 6, 2008.</ref> However, drywall that is composed of non-biodegradable or persistent toxic additives—including [[EDTA#Environmental_behavior|EDTA]], most plasticizers, and some mildew and fire retardants—presents a challenge, in that it cannot be safely returned to soil or reclaimed by industry without compromising human and environmental health.
  
 
== See also ==
 
== See also ==
−
* [[Ablation]]
+
* [[Cement]]
−
* [[Cement board]]
 
−
* [[Certification mark]]
 
−
* [[Compartmentalization (engineering)|Compartmentalization]]
 
 
* [[Construction]]
 
* [[Construction]]
−
* [[Endothermic]]
+
* [[Fiberglass]]
−
* [[Fire protection]]
+
* [[Fire]]
−
* [[Firestop]]
+
* [[Fire protection engineering]]
−
* [[Firewall (construction)]]
 
 
* [[Gypsum]]
 
* [[Gypsum]]
−
* [[Knockdown texture|Knockdown]]
+
* [[Masonry]]
−
* [[Product certification]]
+
* [[Paper]]
−
* [[United States Gypsum]]
+
* [[Plaster]]
−
* [[Custom Building Products]]
+
* [[Plumbing]]
−
* [[SelectCrete, Inc. (Cement Backerboard Only)]]
+
* [[Potash]]
−
* [[National Gypsum]]
+
 
 +
== Notes ==
 +
<references/>
  
 
==References==
 
==References==
−
<div class = "references-small">
+
* Ferguson, Myron. ''Drywall: Professional Techniques for Great Results.'' Newtown, CT: Taunton Press, 2008. ISBN 1561589551
−
<references/>
+
* Scharff, Robert. ''Drywall Construction Handbook.'' New York: McGraw-Hill, 1995. ISBN 0070571244
−
</div>
+
* Wagner, John D., and Clarke Barre. ''Drywall: Pro Tips for Hanging & Finishing.'' Upper Saddle River, NJ: Creative Homeowner Press, 2005. ISBN 1580112706
  
 
== External links ==
 
== External links ==
−
{{commons|Drywall|Drywall}}
+
All links retrieved January 30, 2024.
−
===Photos & Tutorials===
 
−
* [http://wconline.com Walls & Ceilings magazine]Get a free subscription to the Voice of the Industry since 1938.
 
−
* [http://www.drywallinfo.com Taping Drywall Tutorial] A Step-by-step Tutorial For Taping and Finishing Drywall. Written For The Do-It-Yourselfer
 
−
* [http://www.onlinetips.org/installing-drywall-ceiling Installing Drywall on Ceilings] Do It Yourself Site’s Article on Installing Drywall
 
−
* [http://www.naturalhandyman.com/iip/infdrywall/infdrywallcompound.shtm Drywall Compound] How to choose, mix, and store drywall joint compound
 
−
* [http://www.woodzone.com/articles/fixing_drywall.htm Patching holes in drywall guide]
 
−
 
 
−
===Associations, etc.===
 
−
* [http://www.gypsum.org/ Gypsum Association] is an organization owned by several manufacturers of gypsum board in the US and Canada
 
−
* [http://www.drywallscrapping.com/ Drywall Scrapping and Recycling] DRS Inc. is a company that is able to remove and recycle 100% of drywall waste from job sites
 
−
* [http://www.drywallrecycling.org/ Drywall recycling]
 
−
* [http://www.drywallca.com/ Drywall Information Trust Fund]
 
  
−
===History===
+
* [http://www.drywallschool.com/textures.htm Pictures of Various Drywall Textures.] drywallschool.com.
−
* [http://db.inman.com/inman/content/subscribers/inman/column.cfm?StoryId=031201AG&columnistid=Gellner Essay on the history of Sheetrock in the US]
+
* [http://www.drywallinfo.com Drywall Information For The Do-It-Yourselfer.] (A stepwise tutorial for taping and finishing drywall.)
 +
* [http://www.gypsum.org/ Gypsum Association].
 +
* [http://www.drywallrecycling.org/ Drywall recycling.]  
  
 
[[Category:Physical sciences]]
 
[[Category:Physical sciences]]

Latest revision as of 21:16, 30 January 2024

"Sheetrock" redirects here.
Example of drywall, the common interior building material, with joint compound.

Drywall is a common manufactured building material used globally for the finish construction of interior walls and ceilings. Each panel of drywall is made of a paper liner wrapped around an inner core made primarily from gypsum plaster, the semi-hydrous form of calcium sulfate (CaSO4.½ H2O).

The use of drywall offers the advantages of speed in construction and relative affordability. North America is one of the largest gypsum board users in the world, and the gypsum board market is one of the biggest beneficiaries when there is a housing boom.

Alternative names

Drywall is also commonly known as gypsum board, wallboard, plasterboard (U.S., UK, Ireland, Australia), Gibraltar board or gib (New Zealand—GIB being a trademark of Winstone Wallboards), rock lath, Sheetrock (a trademark of United States Gypsum Company), gyproc (Canada, Australia, UK), pladur (Spain—after the Pladur brand), or rigips (Germany and Central Europe—after the Rigips brand), or simply board.

Preparation of drywall

Raw gypsum must be calcined before use. Flash calciners typically use natural gas today. The plaster is mixed with fiber (typically paper and/or fiberglass), plasticizer, foaming agent, potash as an accelerator, EDTA or other chelate as a retarder, various additives that increase mildew and fire resistance (fiberglass or vermiculite), and water. This is then formed by sandwiching a core of wet gypsum between two sheets of heavy paper or fiberglass mats. When the core sets and is dried in a large drying chamber, the sandwich becomes rigid and strong enough for use as a building material. Drying chambers typically use natural gas today. Depending on plant efficiency and energy costs, 25-45 percent of drywall cost today is related to energy, primarily natural gas.

Construction techniques

Drywall is delivered to a building site on a flatbed truck and unloaded with a forked material handler crane. The bulk drywall sheets are unloaded directly to upper floors via a window or exterior doorway.

As opposed to a week-long plaster application, an entire house can be drywalled in one or two days by two experienced drywall mechanics (drywallers) and drywall is easy enough to use that it can be installed by many amateur home carpenters. In large-scale commercial construction, the work of installing and finishing drywall is often split between the drywall mechanics, or hangers, who install the wallboard, and the tapers and mudmen, or float crew, who finish the joints and cover the nail heads with drywall compound.

Drywall is cut to size, using a large T-square, by scoring the paper on the front side (usually white) with a utility knife, breaking the sheet along the cut, scoring the paper backing, and finally breaking the sheet in the opposite direction. Small features such as holes for outlets and light switches are usually cut using a keyhole saw or a small high-speed bit in a rotary tool. Drywall is then fixed to the wall structure with nails, or more commonly in recent years, the now-ubiquitous drywall screws.

Drywall fasteners, also referred to as drywall clips or stops, are gaining popularity in both residential and commercial construction. Drywall fasteners are used for supporting interior drywall corners and replacing the non-structural wood or metal blocking that traditionally was used to install drywall. Their function serves to save on material and labor expenses; to minimize call backs due to truss uplift; to increase energy efficiency; and to make plumbing and electrical installation simpler. Many green building and energy efficiency models suggest using drywall fasteners to conserve resources and save energy, including the U.S. Dept. of Energy.

Drywall screws have a curved, bugle-shaped top, allowing them to self-pilot and install rapidly without punching through the paper cover. These screws are set slightly into the drywall. When drywall is hung on wood framing, screws having an acute point and widely spaced threads are used. When drywall is hung on light-gauge steel framing, screws having an acute point and finely spaced threads are used. If the steel framing is heavier than 20-gauge, self-tapping screws with finely spaced threads must be used. In some applications, the drywall may be attached to the wall with adhesives.

Electric screw gun used to drive drywall screws.

After the sheets are secured to the wall studs or ceiling joists, the seams between drywall sheets are concealed using joint tape and several layers of joint compound (sometimes called "mud"). This compound is also applied to any screw holes or defects. The compound is allowed to air dry then typically sanded smooth before painting. Alternatively, for a better finish, the entire wall may be given a skim coat, a thin layer (about 1 mm or 1/16 inch) of finishing compound, to minimize the visual differences between the paper and mudded areas after painting.

Another similar skim coating is always done in a process called veneer plastering, although it is done slightly thicker (about 2 mm or 1/8 inch). Veneering uses a slightly different specialized setting compound ("finish plaster") that contains gypsum and lime putty. For this application blueboard is used which has special treated paper to accelerate the setting of the gypsum plaster component. This setting has far less shrinkage than the air-dry compounds normally used in drywall, so it only requires one coat. Blueboard also has square edges rather than the tapered-edge drywall boards. The tapered drywall boards are used to countersink the tape in taped jointing whereas the tape in veneer plastering is buried beneath a level surface. One coat veneer plaster over dry board is an intermediate style step between full multi-coat "wet" plaster and the limited joint-treatment-only given "dry" wall.

Common drywall tools

  • Benches
  • Chalk line
  • Checker
  • Corner trowels
  • Dimpler
  • Drywall Adhesive Glue Guns
  • Drywall Cart
  • Drywall Fastener
  • Drywall (Hatchet) Hammer
  • Drywall Lifter
  • Drywall Jack
  • Drywall screws and nails
  • Electric screwdriver
  • Joint compound
  • Keyhole saw or drywall router
  • Pencil and Chalk
  • Surform
  • Screw gun
  • Stud finder
  • Tape Measure
  • Taping/joint knives
  • T-squares (48 and 54 inch)
  • Utility knife

Levels of finish

Reviewing industry standards for gypsum board finish, George Kutcher, Jr., opens with the following statement in Tech Talk of the National Gypsum Association:[1]

In 1990, four major trade associations, the Association of Wall and Ceiling Industries International (AWCI), the Ceilings and Interior Systems Construction Association (CISCA), the Gypsum Association (GA), and the Painting and Decorating Contractors of America (PDCA), presented the consensus document Levels of Gypsum Board Finish. The document was created to "precisely describe" the desired finish of walls and ceilings prior to final decoration. This precise description enables contractors to better understand the requirements of architects and building owners in order to enhance the satisfaction of the client. Specifications that include the Levels of Gypsum Board Finish also promote competitive bidding that allows the bidder to consider the correct labor and materials to finish the wall suitably for its final decoration.

The official document (summarized below) is known as "Recommended Levels of Gypsum Board Finish."[2]

Level 0

No taping, finishing, or accessories required.

Usage: Temporary construction or when final decoration is undetermined.

Level 1

All joints and interior angles shall have tape set in joint compound. Surface shall be free of excess joint compound. Tool marks and ridges are acceptable.

Usage: Above false ceilings or other areas which are out of public view where a degree of fire and noise resistance is required.

Level 2

All joints and interior angles shall have tape embedded in joint compound and wiped with a joint knife leaving a thin coating of joint compound over all joints and interior angles. Fastener heads and accessories shall be covered with a coat of joint compound. Surface shall be free of excess joint compound. Tool marks and ridges are acceptable. Joint compound applied over the body of the tape at the time of tape embedment shall be considered a separate coat of joint compound and shall satisfy the conditions of this level.

Usage: As a substrate for tile walls and ceilings as well as in garages, warehouses, and other places where appearance is not a primary concern.

Level 3

All joints and interior angles shall have tape embedded in joint compound and one additional coat of joint compound applied over all joints and interior angles. Fastener heads and accessories shall be covered with two separate coats of joint compound. All joint compound shall be smooth and free of tool marks and ridges. It is recommended that the prepared surface be coated with a drywall primer prior to the application of final finishes.

Usage: Suitable base for heavy-medium textured paint or other thick finishes.

Level 4

All joints and interior angles shall have tape embedded in joint compound and two separate coats of joint compound applied over all flat joints and one separate coat of joint compound applied over interior angles. Fastener heads and accessories shall be covered with three separate coats of joint compound. All joint compound shall be smooth and free of tool marks and ridges. It is recommended that the prepared surface be coated with a drywall primer prior to the application of final finishes.

Usage: "Standard" household and office walls. Used with light or non-textured finishes. Not suitable for harsh lighting conditions which may highlight minor imperfections.

Level 5

All joints and interior angles shall have tape embedded in joint compound and two separate coats of joint compound applied over all flat joints and one separate coat of joint compound applied over interior angles. Fastener heads and accessories shall be covered with three separate coats of joint compound. A thin skim coat of joint compound, or a material manufactured especially for this purpose, shall be applied to the entire surface. The surface shall be smooth and free of tool marks and ridges. It is recommended that the prepared surface be coated with a drywall primer prior to the application of finish paint.

Usage: The skim coat is a final leveling agent suitable to smooth out a surface to be used under the harshest lighting conditions that may otherwise highlight any imperfections under the finished surface. This finish is highly recommended for gloss and entirely non-textured surfaces.

Fire resistance

When used as a component in fire barriers, drywall is a passive fire protection item. In its natural state, gypsum contains the water of crystallization bound in the form of hydrates. When exposed to heat or fire, this water is vaporized, retarding heat transfer. Therefore, a fire in one room that is separated from an adjacent room by a fire-resistance rated drywall assembly will prevent the adjacent room from getting any warmer than the boiling point of water (100°C), until the water in the gypsum is gone. This makes drywall an ablative material because as the hydrates sublime, a crumbly dust is left behind, which, along with the paper, is sacrificial.

Generally, the more layers of "Type X" drywall one adds, the more one increases the fire-resistance of the assembly, be it horizontal or vertical. Evidence of this can be found both in publicly available design catalogues on the topic, as well as common certification listings. Type X drywall is formulated by adding glass fibers to the gypsum, to increase the resistance to fires, especially once the hydrates are spent, which leaves the gypsum in powder form. Type X is typically the material chosen to construct walls and ceilings that are required to have a fire-resistance rating.

Fire testing of drywall assemblies for the purpose of expanding national catalogs—such as the National Building Code of Canada, Germany's Part 4 of DIN4102 and its British cousin BS476—are a matter of routine research and development work in more than one nation and can be sponsored jointly by national authorities and representatives of the drywall industry. For example, the National Research Council of Canada routinely publishes such findings.[3] The results are printed as approved designs in the back of the building code. Generally, exposure of drywall on a panel furnace removes the water and calcines the exposed drywall and also heats the studs and fasteners holding the drywall. This typically results in deflection of the assembly towards the fire, as that is the location where the sublimation occurs, which weakens the assembly, due to the fire influence.

  • A typical fire problem: The measures taken by the plumbers and the drywallers are at cross-purposes.

  • Another example: This steel sleeve, a penetrant itself, causes more problems than it solves.

  • Penetrants have been punched and burned through drywall, compromising its integrity.

  • Mechanical shaft with compromised fire-resistance rating through pipe installation.

  • Finished, painted, fire-resistance rated drywall assembly. A common deficiency: Lift ceiling tiles and find electrical and mechanical service penetrations without a firestop.

  • Improper drywall and absent firestops at Cambrian College, Greater Sudbury, Ontario, Canada.

  • Improper Firestop and Fireproofing interface, August 2000, Cambrian College, Greater Sudbury, Ontario, Canada.

  • Improper breach of fire-resistance rated drywall assembly, August 2000, Cambrian College, Greater Sudbury, Ontario, Canada.

  • The "I-was-there-first-scenario," resulting in improper drywall firestops with plastic piping.

North American market

North America hails as one of the largest gypsum board users in the world with a total wallboard plant capacity of 40 billion square feet per year.[4] Moreover, the home building and remodeling markets in North America have increased demand the last five years. The gypsum board market is one of the biggest beneficiaries of the housing boom as "an average new American home contains more than 7.31 metric tons of gypsum."[5]

The introduction in March 2005, of the Clean Air Interstate Rule by the United States Environmental Protection Agency requires power plants to reduce sulfur dioxide emissions by 73 percent by 2018.[6] This rule also requested that 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.[7]

Specifications

In the United States and Canada

Drywall is typically available in 4 ft (1219 mm) wide sheets of various lengths. With the rising popularity of 9 ft (2.7 m) high ceilings in new home construction, 4.5 ft (1372 mm) wide panels have become commonly available as well. Newly formed sheets are cut from a belt, the result of a continuous manufacturing process. In some commercial applications, sheets up to 16 ft (4.9 m) are used. Larger sheets make for faster installation, since they reduce the number of joints that must be finished. Often, a sizable quantity of any custom length may be ordered, from factories, to exactly fit ceiling-to-floor on a large project.

The most commonly used drywall is one-half-inch thick but can range from one quarter (6.35 mm) to one inch (25.4 mm). For soundproofing or fire resistance, two layers of drywall are sometimes laid at right angles to each other. In North America, five-eighths-inch-thick drywall with a one-hour fire-resistance rating is often used where fire resistance is desired.

Drywall provides a thermal resistance R-value of 0.32 for three-eighths-inch board, 0.45 for half inch, 0.56 for five-eighths inch and 0.83 for one-inch board. In addition to increased R-value, thicker drywall has a higher sound transmission class.

In the United Kingdom

In the UK, plasterboard is typically manufactured in metric sizes, with the common sizes being close to the earlier imperial sizes.

Most plasterboard is made in 1200 mm wide sheets, though 900 mm wide sheets are also made. 1200 mm wide plasterboard is most commonly made in 2400 mm lengths, though 2700 mm and 3000 mm length sheets are also commonly available.

The most commonly used thicknesses of plasterboard available are 12.5 mm (modern equivalent of half an inch), typically used for walls, and 9.5 mm (modern equivalent of three-eights of an inch), typically used for ceilings. 15 mm thick board is commonly available, and other thicknesses are also produced.

Plasterboard is commonly made with one of two different edge treatments: Tapered Edge, where the sides of the board are tapered at the front to allow for jointing materials to be finished flush with the main board face, and Straight Edge, where there is no different thickness at the side of the board.

Types available in the U.S. and Canada

  • Regular white board, from 1/4" to 3/4" thickness
  • Fire-resistant ("Type X"), different thicknesses and multiple layers of wallboard provide increased fire rating based on the time a specific wall assembly can withstand a standardized fire test. Often perlite, vermiculite and boric acid are added to improve fire resistance.
  • Greenboard, the drywall that contains an oil-based additive in the green colored paper covering that provides moisture resistance. It is commonly used in washrooms and other areas expected to experience elevated levels of humidity.
  • Blueboard or gypsum base, the blue face paper forms a strong bond with a skim coat or a built-up plaster finish
  • Cement backerboard, which is more water-resistant than greenboard, for use in showers or sauna rooms, and as a base for ceramic tile
  • Soundboard is made from wood fibers to increase the sound rating (STC)
  • Soundproof drywall such as QuietRock is a laminated drywall made with gypsum, other materials, and damping polymers to significantly increase the STC
  • Mold-resistant, paperless drywall from Georgia-Pacific
  • Enviroboard, a board made from recycled agricultural materials
  • Lead-lined drywall, a drywall used around radiological equipment
  • Foil-backed drywall to control moisture in a building or room

Handling waste

Because up to 17 percent of drywall is wasted during the manufacturing and installation processes, and the drywall material is rarely re-used, disposal has become a problem. Some landfill sites have banned the dumping of drywall. Therefore, used drywall and gypsum are often dumped into the ocean where it may cause harm to sea life. The EPA regulates this ocean dumping by permit. Most manufacturers with an environmental concern take back the boards from construction sites, and burn them at high temperature to eliminate the paper and bring the gypsum back to its initial plaster state. Recycled paper is sometimes used during manufacturing.

More recently, recycling at the construction site itself is being investigated. There is potential for using crushed drywall to amend certain soils at building sites, such as clay and silt mixtures (bay mud), as well as using it in compost.[8] However, drywall that is composed of non-biodegradable or persistent toxic additives—including EDTA, most plasticizers, and some mildew and fire retardants—presents a challenge, in that it cannot be safely returned to soil or reclaimed by industry without compromising human and environmental health.

See also

Notes

  1. ↑ National Gypsum Company, Tech Talk: Revisiting the Levels of Gypsum Board Finish. Retrieved September 19, 2008.
  2. ↑ AWCI, CISCA, GA, PDCA, GA-214-96, Recommended Levels of Gypsum Board Finish. Retrieved September 19, 2008.
  3. ↑ V.R. Kodur and M.A. Sultan, Performance of wood stud shear walls exposed to fire, National Research Council of Canada. Retrieved September 19, 2008.
  4. ↑ Mineral Commodity Summaries, Gypsum. Retrieved September 6, 2008.
  5. ↑ Donald W. Olson, Gypsum, USGS. Retrieved September 6, 2008.
  6. ↑ Environmental Protection Agency, Clean Air Interstate Rule. Retrieved September 6, 2008.
  7. ↑ Loreal V. Heebink and David J. Hassett, Mercury Release from FGD Gypsum, Flyash.info. Retrieved September 6, 2008.
  8. ↑ California Integrated Waste Management Board, Recycled Inerts. Retrieved September 6, 2008.

References
ISBN links support NWE through referral fees

  • Ferguson, Myron. Drywall: Professional Techniques for Great Results. Newtown, CT: Taunton Press, 2008. ISBN 1561589551
  • Scharff, Robert. Drywall Construction Handbook. New York: McGraw-Hill, 1995. ISBN 0070571244
  • Wagner, John D., and Clarke Barre. Drywall: Pro Tips for Hanging & Finishing. Upper Saddle River, NJ: Creative Homeowner Press, 2005. ISBN 1580112706

External links

All links retrieved January 30, 2024.

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