Drywall (also known as plasterboard , wallboard , gypsum panel, sheet rock , or gypsum board ) is a panel made of calcium sulfate dihydrate (gypsum), with or without additives, usually extruded between a thick sheet of facer paper and a backer, used in the construction of inner walls and ceilings. Plaster is mixed with fiber (usually paper and/or fiberglass or asbestos), plasticizer, foaming agent, and various additives that can reduce moss, increase fire resistance, and lower water absorption.
Construction of drywall is becoming prevalent in North America as a faster alternative than traditional battens and plaster.
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Histori
The first plasterboard factory in England opened in 1888 in Rochester, Kent. Sackett Council was created in 1894 by Augustine Sackett and Fred Kane, a graduate of the Rensselaer Polytechnic Institute. It is made by coating plaster in four layers of wool paper. Sheets are 36 "Ã, ÃÆ'-Ã, 36" Ã, ÃÆ'-Ã, 1/4 "(914Ã, ÃÆ'-Ã, 914Ã, ÃÆ'-Ã, 6.4A mm) thick with open (untapped) edges.
The gypsum board evolved between 1910 and 1930 starting with the edges of the wrapped board and the removal of two layers in the paper feeling supportive of paper-based facings. In 1910, the United States Gypsum Corporation bought the Sackett Plaster Board Company and in 1917 came out with a product they called Sheetrock. Providing installation efficiency, it is developed also as a measure of fire resistance. Then air entrainment technology makes the boards lighter and less brittle, then joint care materials and systems also evolve. Rock reng (gypsum reng) is the starting substrate for plaster. An alternative to traditional wood or metal rattan, it is a panel consisting of a compressed gypsum gypsum board that is occasionally grooved or perforated with a hole to allow a wet cast to enter its surface. When it evolved, it was confronted with paper impregnated with gypsum crystals tied to the applied plaster coating.
In 2002 the European Commission imposed a penalty of EUR478 million on Lafarge, BPB and Gyproc Benelux, which has operated a cartel in the market affecting 80% of consumers in France, Britain, Germany and the Benelux countries.
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Producing
The wallboard panel consists of a plaster gypsum layer flanked between two layers of paper. Gypsum raw, CaSO 4 O, heated to dissipate water then slightly rehydrated to produce calcium sulphate hemihydrate (CaSO 4 Ã,  · ½ H 2 O). Plaster is mixed with fiber (usually paper and/or fiberglass), plasticizer, foaming agent, finely ground gypsum crystals as accelerator, EDTA, starch or other chelate as retarder, various additives that can reduce moss and increase fire resistance, and wax or silane for lower water absorption. The board is then formed by flanking the core of the wet mixture between two sheets of thick paper or fiberglass mat. When the core set is then dried in a large drying chamber, and the sandwich becomes stiff and strong enough to be used as a building material.
The drying chamber usually uses natural gas today. To drain 1 MSF (1,000 square feet (93 m 2 )) of the wallboard, between 1,750,000 and 2,490,000 BTU (1,850,000 and 2,630,000 kJ) are required. Organic dispersants/pellets are used so that the slurry will flow during manufacture, and to reduce water and hence drying time. Coal-fired power plants include a device called a scrubber to remove sulfur from their exhaust emissions. Sulfur is absorbed by limestone powder in a process called flue-gas desulphurization (FGD), which produces a number of new substances. One of them is called "FGD gypsum". These are typically used in drywall construction in the United States and elsewhere.
Specifications
Canada and the United States
The drywall panels in the United States are manufactured in wide panels of 48 inches (1.2 m), 54 inches (1.4 m) and 96 inches (2.4 m) in various sizes to customize applications, although 48 inches is by far the width most common. Lengths up to 16 feet (4.9 m) are usually available, although the most common length is 8 feet (2.4 m). Common panel thicknesses are 1 / 2 -inch (13 mm) and 5 / 8 -inch (16 mm), with panels also available in 1 / 4 -inch (6, 4 mm), 3 / 8 -inch (9.5 mm), 3/4-inch (19.0 mm) and 1 inch (25.4 mm) for specific applications.
Europe
In Europe, plasterboard is produced in metric sizes, with common sizes being a consequence of the old imperial size. Most plasterboard is made with a width of 120 cm, although a width of 90 cm and a width of 60 cm is also made. The 120 cm width width is most commonly made with a length of 240 cm, although 250, 260, 270, 280, 300 cm and even longer (if ordered) are generally available. The available plasterboard thickness is 9.5 mm to 25 mm.
Plasterboard is generally made with one of three different edge treatments: a tapered edge, in which the long edge of the board is tapered with a wide bevel in the front to allow the finished material to finish flush with the face of the main board; ordinary edges, used where the entire surface will receive a thin layer (skim coat) finishing plaster; and, finally, tilted on all four sides, used in special products for the roof. However, four-sided drywall is currently not offered by major UK manufacturers for general use.
Australia and New Zealand
The term plasterboard is used in Australia and New Zealand. Both countries use metric systems in buildings, and plasterboard is produced in thicknesses of 10 mm, 13 mm, and 16 mm, and sometimes other thicknesses of up to 25 mm. Panels are generally sold at 1200 Ã, Â ± 2400 mm, 1200 Ã, Â ± 4800 mm, and 1200 Ã, Â ± 6000 mm sheets. Bed sheets are usually secured either to wood or cold-formed steel frames anywhere from 150 to 300 mm centers along the beam and 400 to 600 mm across the board.
Companies, such as Boral and CSR, produce plasterboard with various brand names including Gyprock.
Construction techniques
As an alternative to weekly plaster applications, the entire house can be dried in a day or two by two experienced drywallers, and drywall is quite easy to use that can be installed by many amateur home carpenters. In large-scale commercial construction, the job of installing and completing drywall is often divided between drywall mechanics, or hangers , which attach wall boards, and shrink and mudmen , or buoy crew , which completes the joints and covers the head of the binder with a drywall compound. Dry walls can be completed anywhere from level 0 to level 5, where 0 is not completed in any mode and 5 is the most "pure". Depending on how important the solution is to the customer, additional steps at the end may or may not be necessary, although drywall painting and painting is recommended at any location that may be exposed to any outfit.
Drywall is cut to size, using a large T-square, by printing paper on the finished side (usually white) with a utility knife, cutting the sheet along the length, and cutting the paper backing. Small features such as outlet holes and light switches are usually cut using a keyhole saw or small high-speed bit in a rotary device. Drywall is then fixed to the wall structure with nails or drywall screw and often glue. Drywall fasteners , also referred to as drywall clips or quit , gaining popularity in residential and commercial construction. Drywall fasteners are used to support the interior drywall angle and replace the non-structural wood or metal blockings traditionally used to install drywall. Their functions serve to save materials and labor costs, to minimize callbacks for truss removal, to improve energy efficiency, and to make installation of pipes and electricity simpler.
The head of the drywall screw has a curved taper, allowing them to pilot themselves and install quickly without having to be perforated. When finished driving, these screws are slightly countersunk to drywall. Screws for steel framing with a light meter have an acute point and a very fine spaced yarn. If steel framing is heavier than 20-gauge, self-tapping screws with fine lined threads should be used. In some applications, drywall can be affixed to the wall with adhesive.
After the bed sheets are secured to the wall studs or ceiling beams, the installers hide the layers between drywall sheets with 'ribbon joints' and several layers of 'compound' (sometimes called 'mud'), â € <â € Other similar schematic coatings are always done in a process called veneer plastering, although it is done slightly thicker (about 2 mm or 1/8 inch). Coatings use a slightly different special regulatory compound ("complete plaster") containing gypsum and lime putty. This application uses blueboard, which has special paper treated to speed up the arrangement of gypsum plaster components. This arrangement has much less shrinkage than the dry air compounds normally used in drywall, so it only takes one layer. Blueboard also has a square edge rather than a tapered-edge drywall board. Pointy drywall boards are used to calculate the tape bands in a paired joint while the plastering on the veneer plaster is buried beneath a flat surface. One layer of veneer plaster on a dry board is a medium-style step between a full "wet" multi-coat plaster and treated only "dry".
Voice control
The mounting method and drywall type can reduce the sound transmission through walls and ceilings. Some builders state that thick drywall reduces voice transmission, but technical guidelines recommend using multiple layers of drywall, sometimes with different thickness and glued, or special types of drywall designed to reduce noise. Also important are the details of framing construction with steel studs, wider stud spacing, double studding, insulation, and other details that reduce voice transmission. Voice transmission class rating (STC) can be upgraded from 33 for the usual stud-wall up to 59 with double 1/2 "drywall on both sides of wood stud walls with tough channels on one side and fiberglass batt insulation between buttons.
Voice transmission can be slightly reduced by using regular <5> -inch / 8 panels with or without a metal duct and/or light scattered insulation), but it is more effective to use two layers of drywall, sometimes combined with other factors, or a specially designed and sound-proof drywall.
Water damage and mold
Drywall is particularly vulnerable to moisture due to the inherent properties of ingredients comprising: gypsum, paper, and organic and binder additives. Gypsum will soften with moisture exposure, and eventually switch to sticky paste with prolonged dyeing, such as during flooding. During such incidents, some or all of the drywall throughout the building may need to be removed and replaced. Furthermore, the surface paper and organic additives mixed with the gypsum core are food for molds.
Porosity boards - introduced during manufacturing to reduce board weight, decrease construction time and transportation costs - allow water to reach the core rapidly through the capillaries, where the fungus can grow in it. Water entering the room from above can cause ceiling drywall ceilings separate from the ceiling as a result of the grooves immediately behind the tape where the drywall pieces become saturated. Drywall may also soften around the screw holding drywall in place and with the help of gravity, heavy water can cause drywall to sag and eventually collapse, requiring replacement.
Drywall paper walls can be eaten by termites, which can eat paper if they step on a wall cavity covered with a dry wall. This causes the painted surface to crumble to the touch, the paper backing material has been eaten. In addition to the need to patch up damaged surfaces and repaint, if enough paper has been eaten, the gypsum core can be easily cracked or crushed without it and the drywall should be removed and replaced.
In many circumstances, especially when drywall has been exposed to water or moisture for less than 48 hours, professional restoration experts familiar with the structural drying methodology can introduce rapid drying techniques designed to eliminate the elements needed to support microbial activity while also recovering most or all of drywall and thus avoid the costs, discomforts, and difficulties of eliminating and replacing the affected drywall.
For this reason green boards and cement boards are ideally used for rooms that are expected to have high humidity, especially kitchens, bathrooms, and laundry rooms.
High sulfur drywall disease and corrosion problems
A large number of damaged drywall were imported into the United States from China and put into tens of thousands of homes during rebuilding in 2006 and 2007 after Hurricane Katrina and elsewhere. Complaints include odor, health effects, and corrosion of metals within the structure. This is caused by sulfur gas emissions. The same drywall is sold in Asia without any problems, but US homes are built much more tightly than houses in China, with fewer ventilation. Volatile sulfur compounds, including hydrogen sulfide, have been detected as emissions from imported drywall and may be related to health problems. These compounds are emitted from different types of drywall.
A number of lawsuits are being made in many jurisdictions, but many drywall sheets are only marked, "Made in China", thus making identification of producers difficult. An investigation by the Consumer Product Safety Commission, CPSC, is underway in 2009. In November 2009, the CPSC reported a "strong relationship" between Chinese drywall and pipeline and cable corrosion reported by thousands of homeowners in the United States. This problem was solved in 2011 and now all drywall must be tested for volatile sulfur and any containing more than 10 ppm can not be sold in the US.
Flame retard
Drywall is made mainly from gypsum (CaSO 4 o2H 2 O). As the chemical formula shows, gypsum contains a chemical water mixture (about 50% by volume). When the gypsum panel is exposed to heat, the heat is absorbed as part of a combined water that is turned off as a vapor. This chemical process is called calcination. The heat energy that converts water to steam is thus shifted and absorbed, keeping the opposite side of the gypsum panel cool as long as any remaining crystalline water is to be converted into steam or until the gypsum panel is violated. In the case of ordinary gypsum boards, because the crystal water is moved, the volume reduction inside the gypsum core causes large cracks to form, eventually causing the panel to fail due to loss of structural integrity. This is similar to cracks that can be observed in dry lakes or riverbeds.
When used as a component in a fire barrier, drywall is a passive fire protection item. In its natural state, gypsum contains water crystallization which is bound in the form of hydrate. When exposed to heat or fire, this water is evaporated, above the temperature range from 80 ° to 170 ° C (see calcium sulfate), slowing heat transfer until the water inside the gypsum is lost. This makes drywall an ablative material because as a noble hydrate, the fragile dust is left behind, which, along with the paper, is a sacrifice. In general, the more layers of X-type drywall one adds, the more increasing the fireproof of the assembly, up to four hours for the wall and three hours for the ceiling. This evidence can be found in both the publicly available design catalog, including DIN 4102 Part 4 and the Canadian Building Code on the topic, as well as a list of general certifications, including a list of certifications provided by Underwriters Laboratories and Underwriters Laboratories of Canada (ULC). Drywall "Type X" is formulated by adding glass fiber to gypsum, to increase fire resistance, particularly the spent hydrate, which leaves gypsum in powder form. Type X is usually the material chosen to build walls and ceilings that must have a fireproof rating.
Fire testing of drywall assemblies for the purpose of expanding national catalogs, such as the National Building Code of Canada, Section 4 DIN4102 Germany and its British cousin, BS476, is a matter of routine research and development in more than one country and may be co-sponsored by national authorities and industry representatives drywall. For example, the Canadian National Research Council routinely publishes these findings. The results are printed as approved designs behind building codes. Generally, drywall exposure on the panel furnace removes water and calcites the open drywall and also heats the buttons and fasteners that hold the drywall. This usually results in deflection of the assembly towards the fire, because it is the location where sublimation occurs, which weakens the assembly, due to the influence of fire.
Testing of sponsored results will result in a design code that is recognized with a defined fire resistance rating. The resulting design becomes part of the code and is not limited to use by any of the manufacturers. However, individual producers may also have exclusive designs that have been tested and approved by third parties. It is provided that the materials used in the field configuration can be shown to meet the minimum requirements of Type X drywall (such as entry in the appropriate category of UL Building Material Directory or in the Gypsum Fire Resistance Association and the Voice Control Manual Design) and that sufficient layers and thickness are used. The fire test report for a unique third party test is confidential but may be made available to the code officer on special request.
It is important to consider deflections of drywall assemblies to maintain the integrity of their assembly to maintain their ratings. The deflection of the drywall assembly may vary from one test to another. Importantly, penetrants do not follow the deflection movements of the drywall assemblies they penetrate. For example, see the cable tray movement in German tests. Therefore, it is important to test firestop in a full-scale wall panel test, so that the deflection of any applicable assembly can be taken into account.
The size of the test wall assemblies alone is not the only consideration for firestop tests. If the penetrant is attached and hung on the drywall assembly itself during the test, this is not a realistic deflection exposure as far as the firestop is concerned. In fact, at the construction site, the penetrant is suspended in the ceiling above. Penetrants may increase in length, thrust and pull as a result of changes in operational temperature (eg, hot and cold water in pipes), especially in fires. But it is the physical impossibility to have penetrants following the movement of the drywall assemblies they penetrate, as they are not fitted to the drywall in the building.
Therefore, it is counterproductive to suspend the penetration of the drywall assembly during a fire test. When the downward deflection of the drywall assembly and bend towards the fire occurs, the top of the firestop is squeezed and the bottom of the firestop is pulled. This is the above motion caused by expansion of metal penetration due to exposure to heat in the flame. Both types of motion occur because the first metal expands in fire, and then softens after the critical temperature has been reached, as described under the structural steel. To simulate the effects of drywall deflection, one can easily attach a penetrant to a steel frame that holds the test assembly. The fire-induced operation and movement of the penetrant, which is independent of the penetrated assembly, can be arranged separately.
Drywall gives a R-value of thermal (in US units) of 0.32 boards for 3 / 8 , 0.45 for 1 / 2 -inch, 0.56 for 5 / 8 - inches, and 0.83 for 1 inch boards. In addition to the increase in R-values, the thicker drywall has a higher sound transmission class.
Type X drywall
On an X type gypsum board, a special glass fiber mixes with gypsum to strengthen the core of the panel. This fiber has the effect of reducing the size of the cracks formed when the water is moved, thus extending the length of time the gypsum panel retains fire without failure.
Type C Drywall
The C type gypsum panel provides even greater fire resistance than Type X. Like the Type X panel, the Type C core panels contain glass fibers, only in percent higher by weight. In addition to the larger number of glass fibers, the Type C core panels also contain vermiculite, which acts as a subtracting reducing additive when exposed to high fire temperatures. This expansion occurs at temperatures roughly equal to the calcification of gypsum in essence. This allows the core of the Type C panel to remain dimensionally stable in the presence of fire, which in turn allows the panel to remain in place for a longer period of time even after the combined water has been moved.
North American Market
North America is one of the largest users of gypsum board in the world with a total factory capacity of 42,000,000,000 square feet (3.9 ÃÆ' - 10 9 m 2 ) per year (worldwide 85,000,000,000 square feet (7,9 ÃÆ' - 10 9 Ã, m 2 ) per year). In addition, rebuilding and renovation markets in North America in the late 1990s and early 2000s increased demand. The gypsum board market is one of the largest beneficiaries of housing explosions because "the average new home in America contains more than 7.31 metric tons of gypsum."
The introduction in March 2005 of the Interstate Clean Air Regulations by the United States Environmental Protection Agency requires a power plant to "cut sulfur dioxide emissions by 73%" by 2018. The Interstate Clean Air Regulations also require that power plants install new scrubbers (industrial pollution control devices) to remove the sulfur dioxide present in the exhaust gas output. Scrubber uses a flue gas desulfurization technique (FGD), which produces a synthetic cast as a byproduct that can be used. In response to this new supply of raw materials, the gypsum board market is predicted to shift significantly. However, problems such as mercury release during calcination need to be resolved.
Types available in the US and Canada
- Ordinary white board, from 1/4 "to 3/4" thickness
- Flame retardant ("Type X"), different thickness and multiple layers of wall board provides an increase in fire rating based on the time a particular wall assembly can withstand standard fire assay. Often pearlite, vermiculite, and boric acid are added to improve fire resistance.
- Greenboard, a drywall containing oil-based additives on a green cover paper that provides moisture resistance. This is usually used in bathrooms and other areas that are expected to experience high humidity levels.
- Blueboard, blue face paper forms a strong bond with a skim layer or plaster layer that is built providing water and mushroom resistance.
- Cement boards, which are more waterproof than green boards, for use in bathrooms or saunas, and as a base for ceramic tiles.
- The soundboard is made of wood fiber to enhance the sound transmission class.
- Soundproof Drywall is a layered drywall made of gypsum and other materials such as damping polymers to significantly improve the class rating of voice transmission.
- Mold-resistant, paperless drywall.
- Enviroboard, board made from recycled agricultural materials
- lead-lined drywall, drywall used around radiology equipment.
- Drywall supported by Foil is used as a vapor barrier.
- Controlled density (CD), also called a ceiling board, is available only in 1/2 "thickness and significantly louder than plain white boards.
- EcoRock, a drywall that uses a combination of 20 materials including recycled fly ash, slag, dust and kiln filler and no starch cellulose; it is advertised as environmentally friendly due to the use of recyclable materials and energy efficient processes.
- Gypsum "Firecode C". This board has the same composition as Type X, except for more glass fibers and vermiculite forms, used to reduce shrinkage. When exposed to high heat, the gypsum core shrinks but this additive expands at about the same level, so the gypsum core is more stable in the flame, and remains in place even after the gypsum dries.
Waste
Since up to 12% of drywall is wasted during the manufacturing and installation process and drywall material is often not reused, disposal can be a problem. Some landfill sites have banned the drywall disposal. Some manufacturers take back the used wallboard from the construction site and recycle it into a new wallboard. Recycled paper is usually used during manufacture. Recently, recycling at the construction site itself is being investigated. There is the potential to use crushed drywall to alter certain soils at building sites, such as sodic clay and mud mixtures (mud bay), and use them in compost. By 2016, industry standards are being developed to ensure that when and when wall boards are taken back for recycling, quality and composition are maintained.
See also
References
External links
- www.drywall-how-to.com
Source of the article : Wikipedia
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