Drywall, also known as
plasterboard,
wallboard or
gypsum board is a panel made of gypsum plaster pressed between two thick sheets of paper. It is used to make interior walls and ceilings.
Drywall construction became prevalent as a speedier alternative to traditional
lath and plasterLath and plaster is a building process used mainly for interior walls in Canada and the United States until the late 1950s. After the 1950s, drywall began to replace the lath and plaster process in the United States. In the United Kingdom, lath and plaster was used for some interior partition...
.
In many places the common term is a
genericized trademarkA genericized trademark is a trademark or brand name that has become the colloquial or generic description for, or synonymous with, a general class of product or service, rather than as an indicator of source or affiliation as intended by the trademark's holder...
such as
gib,
sheetrock or
gyproc.
History
"
Sackett Board" was invented in 1894 by Augustine Sackett and Fred Kane. It was made by layering plaster within four plies of wool felt paper. Sheets were 36" × 36" × 1/4" thick with open (untaped) edges."
"
Gypsum Board" evolved between 1910 and 1930 beginning with wrapped board edges, and elimination of the two inner layers of felt paper in favor of paper-based facings. Providing efficiency of installation, it was developed additionally as a measure of fire resistance. Later
air entrainment-Air entrainment in concrete:Air entrainment is the intentional creation of tiny air bubbles in concrete. The bubbles are introduced into the concrete by the addition to the mix of an air entraining agent, a surfactant...
technology made boards lighter and less brittle, then joint treatment materials and systems also evolved. "
"
Rock Lath" was an early substrate for plaster. An alternative to traditional wood or metal lath, it was a panel made up of compressed gypsum plaster board that was sometimes grooved or punched with holes to allow wet plaster to key into its surface. As it evolved, it was faced with paper impregnated with gypsum crystals that bonded with the applied facing layer of plaster.
Manufacture
A wallboard panel is made of a
paperPaper is a thin material mainly used for writing upon, printing upon, drawing or for packaging. It is produced by pressing together moist fibers, typically cellulose pulp derived from wood, rags or grasses, and drying them into flexible sheets....
liner wrapped around an inner core made primarily from gypsum plaster. The raw
gypsumGypsum is a very soft sulfate mineral composed of calcium sulfate dihydrate, with the chemical formula CaSO4·2H2O. It is found in alabaster, a decorative stone used in Ancient Egypt. It is the second softest mineral on the Mohs Hardness Scale...
, CaSO
4·2 H
2O, (mined or obtained from
flue gas desulfurizationSulfur dioxide is one of the elements forming acid rain. Tall flue-gas stacks disperse emissions by diluting the pollutants in ambient air and transporting them to other regions....
(FGD)) must be
calcinedCalcination is a thermal treatment process applied to ores and other solid materials to bring about a thermal decomposition, phase transition, or removal of a volatile fraction. The calcination process normally takes place at temperatures below the melting point of the product materials...
before use to produce the hemihydrate of
calcium sulfateCalcium sulfate is a common laboratory and industrial chemical. In the form of γ-anhydrite , it is used as a desiccant. It is also used as a coagulant in products like tofu. In the natural state, unrefined calcium sulfate is a translucent, crystalline white rock...
(CaSO
4·½ H
2O). This is done in kettle or flash calciners, typically using natural gas today. The plaster is mixed with fiber (typically paper and/or fiberglass),
plasticizerPlasticizers or dispersants are additives that increase the plasticity or fluidity of the material to which they are added; these include plastics, cement, concrete, wallboard, and clay. Although the same compounds are often used for both plastics and concretes the desired effects and results are...
,
foaming agentA foaming agent is a surfactant, which when present in small amounts, facilitates the formation of a foam, or enhances its colloidal stability by inhibiting the coalescence of bubbles....
, finely ground gypsum crystal as an accelerator,
EDTAEthylenediaminetetraacetic acid, widely abbreviated as EDTA , is a polyamino carboxylic acid and a colourless, water-soluble solid. Its conjugate base is named ethylenediaminetetraacetate. It is widely used to dissolve limescale. Its usefulness arises because of its role as a hexadentate ligand...
,
starchStarch or amylum is a carbohydrate consisting of a large number of glucose units joined together by glycosidic bonds. This polysaccharide is produced by all green plants as an energy store...
or other chelate as a retarder, various additives that may increase
mildewMildew refers to certain kinds of molds or fungi.In Old English, it meant honeydew , and later came to mean mildew in the modern sense of mold or fungus....
and/or fire resistance (fiberglass or
vermiculiteVermiculite is a natural mineral that expands with the application of heat. The expansion process is called exfoliation and it is routinely accomplished in purpose-designed commercial furnaces. Vermiculite is formed by weathering or hydrothermal alteration of biotite or phlogopite...
),
waxthumb|right|[[Cetyl palmitate]], a typical wax ester.Wax refers to a class of chemical compounds that are plastic near ambient temperatures. Characteristically, they melt above 45 °C to give a low viscosity liquid. Waxes are insoluble in water but soluble in organic, nonpolar solvents...
emulsion or
silanesSilanes are chemical compounds of silicon and hydrogen, which are analogues of alkane hydrocarbons. Silanes consist of a chain of silicon atoms covalently bonded to each other and to hydrogen atoms. The general formula of a silane is SinH2n+2...
for lower water absorption 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. To dry 1 MSF ( 1000 square feet (92.9 m²) ) of wallboard, between 1.75 and 2.49 million BTU is required. Organic dispersants/plasticisers are used mainly to reduce the amount of water, hence reduce the eventual drying time, needed to produce gypsum slurry flow during wallboard manufacture.
USA and Canada
Drywall panels are manufactured in 48 inches (121.9 cm) and 54 inches (137.2 cm) wide panels in varying lengths to suit the application. Common panel thicknesses are 1/2" (12.7 mm) and 5/8" (16 mm), with panels also available in 1/4" (6 mm) and 3/8" (10 mm). Both 1/2" (12.7 mm) and 5/8" (16 mm) panels of TYPE 'X' (a gypsum board with special core additives to increase the natural fire resistance of regular gypsum board) are used where a fire-resistance rating is desired. Regular 5/8" (16 mm) panels are used (with or without light gauge resilient metal channels) where additional mass is needed for the reduction of sound transmission.
Drywall provides a thermal resistance
R-valueThe R-value is a measure of thermal resistance used in the building and construction industry. Under uniform conditions it is the ratio of the temperature difference across an insulator and the heat flux through it or R = \Delta T/\dot Q_A.The R-value being discussed is the unit thermal resistance...
(in US units) of 0.32 for 3/8" board, 0.45 for 1/2", 0.56 for 5/8", and 0.83 for 1" board. In addition to increased R-value, thicker drywall has a higher
sound transmission classSound Transmission Class is an integer rating of how well a building partition attenuates airborne sound. In the USA, it is widely used to rate interior partitions, ceilings/floors, doors, windows and exterior wall configurations . Outside the USA, the Sound Reduction Index ISO standard is used...
.
Europe
In the UK and Europe, plasterboard is manufactured in metric sizes, with the common sizes being corollaries of old imperial sizes.
Most plasterboard is made in 120 cm wide sheets, though 90 cm and 60 cm wide sheets are also made. 120 cm wide plasterboard is most commonly made in 240 cm lengths, though 270 cm and 300 cm length sheets are also commonly available.
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 long edges of the board are tapered with a wide bevel at the front to allow for jointing materials to be finished flush with the main board face, and plain edge, used where the whole surface will receive a thin coating (skim coat) of finishing plaster.
Construction techniques
As an alternative to a week-long plaster application, an entire house can be drywalled in one or two days by two experienced
drywallersA drywall mechanic is a carpenter who specializes in the installation of drywall. The drywall mechanic may also do the finishing work of "mudding and taping", or this part of the task may be done by a drywall finisher, known as a mudman or taper....
, 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 nailheads with drywall compound.
Drywall is cut to size, using a large
T-squareA T-square is a technical drawing instrument used by draftsmen primarily as a guide for drawing horizontal lines on a drafting table. It may also guide a triangle to draw vertical or diagonal lines. Its name comes from the general shape of the instrument where the horizontal member of the T slides...
, by scoring the paper on the front side (usually white) with a
utility knifeA utility knife is a knife used for general or utility purposes. The utility knife was originally a fixed blade knife with a cutting edge suitable for general work such as cutting hides and cordage, scraping hides, butchering animals, cleaning fish, and other tasks.Today, the term "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 sawA keyhole saw is a long, narrow saw used for cutting small, often awkward features in various building materials...
or a small high-speed bit in a rotary tool. Drywall is then fixed to the
wallA wall is a usually solid structure that defines and sometimes protects an area. Most commonly, a wall delineates a building and supports its superstructure, separates space in buildings into rooms, or protects or delineates a space in the open air...
structure with
nailsIn woodworking and construction, a nail is a pin-shaped, sharp object of hard metal or alloy used as a fastener. Formerly wrought iron, today's nails are typically made of steel, often dipped or coated to prevent corrosion in harsh conditions or improve adhesion...
, glue, or more commonly in recent years, the now-ubiquitous
drywall screwA screw, or bolt, is a type of fastener characterized by a helical ridge, known as an external thread or just thread, wrapped around a cylinder. Some screw threads are designed to mate with a complementary thread, known as an internal thread, often in the form of a nut or an object that has the...
s.
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
blockingBlocking may refer to:- Telecommunications and computing :*Block , a sequence of bytes or bits, having a nominal length*Block , technical measures to restrict users' access to certain internet resources...
that traditionally was used to install drywall. Their function serves to save on material and labour expenses, to minimize call-backs due to truss uplift, to increase
energy efficiencyEfficient energy use, sometimes simply called energy efficiency, is the goal of efforts to reduce the amount of energy required to provide products and services. For example, insulating a home allows a building to use less heating and cooling energy to achieve and maintain a comfortable temperature...
, and to make plumbing and electrical installation simpler.
Drywall screws heads have a curved taper, 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 framingFraming, in construction known as light-frame construction, is a building technique based around structural members, usually called studs, which provide a stable frame to which interior and exterior wall coverings are attached, and covered by a roof comprising horizontal ceiling joists and sloping...
, 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-tappingSelf-tapping is the ability of a screw to advance when turned, while creating its own thread. This ability is sometimes created by a gap in the continuity of the thread on the screw. These edges cut a thread as the screw is driven in to the material...
screws with finely spaced threads must be used. In some applications, the drywall may be attached to the wall with
adhesiveAn adhesive, or glue, is a mixture in a liquid or semi-liquid state that adheres or bonds items together. Adhesives may come from either natural or synthetic sources. The types of materials that can be bonded are vast but they are especially useful for bonding thin materials...
s.
After the sheets are secured to the wall studs or ceiling
joistA joist, in architecture and engineering, is one of the horizontal supporting members that run from wall to wall, wall to beam, or beam to beam to support a ceiling, roof, or floor. It may be made of wood, steel, or concrete. Typically, a beam is bigger than, and is thus distinguished from, a 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 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
puttyPutty is a generic term for a plastic material similar in texture to clay or dough typically used in domestic construction and repair as a sealant or filler. Painter's Putty is typically a linseed oil based product used for filling holes, minor cracks and defacements in wood only...
. This application uses blueboard, 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.
Water damage and mold
Drywall is easily damaged by exposure to water. While it can be waterproofed through
covalentA covalent bond is a form of chemical bonding that is characterized by the sharing of pairs of electrons between atoms. The stable balance of attractive and repulsive forces between atoms when they share electrons is known as covalent bonding....
waterproofingWaterproof or water-resistant describes objects relatively unaffected by water or resisting the ingress of water under specified conditions. Such items may be used in wet environments or under water to specified depths...
, if waterproofing is absent or if the waterproofing layer is punctured, water will cause drywall to swell and eventually disintegrate, requiring replacement. Drywall is a porous, lightweight substance that supports the growth of mold. It is for this reason that greenboard and
cement boardA cement board is a combination of cement and reinforcing fibers formed into 4 foot by 8 foot sheets , 1/4 to 1/2 inch thick that are typically used as a tile backing board...
is used for rooms expected to have high humidity, primarily kitchens, bathrooms and laundry rooms.
Fire resistance
When used as a component in fire barriers, drywall is a
passive fire protectionPassive fire protection is an integral component of the three components of structural fire protection and fire safety in a building. PFP attempts to contain fires or slow the spread, through use of fire-resistant walls, floors, and doors...
item. In its natural state, gypsum contains the
water of crystallizationIn crystallography, water of crystallization or water of hydration or crystallization water is water that occurs in crystals. Water of crystallization is necessary for the maintenance of crystalline properties, but capable of being removed by sufficient heat...
bound in the form of
hydrateHydrate is a term used in inorganic chemistry and organic chemistry to indicate that a substance contains water. The chemical state of the water varies widely between hydrates, some of which were so labeled before their chemical structure was understood....
s. When exposed to
heatIn physics and thermodynamics, heat is energy transferred from one body, region, or thermodynamic system to another due to thermal contact or thermal radiation when the systems are at different temperatures. It is often described as one of the fundamental processes of energy transfer between...
or
fireFire is the rapid oxidation of a material in the chemical process of combustion, releasing heat, light, and various reaction products. Slower oxidative processes like rusting or digestion are not included by this definition....
, 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
ablativeAblation is removal of material from the surface of an object by vaporization, chipping, or other erosive processes. This occurs in spaceflight during ascent and atmospheric reentry, glaciology, medicine, and passive fire protection.-Spaceflight:...
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, including, but not limited to DIN4102 Part 4 and the Canadian Building Code on the topic, as well as common certification listings, including but not limited to
certification listingA certification listing is a document used to guide installations of certified products against which a field installation is compared to make sure that it complies with a regulation, such as a building code...
s provided by
Underwriters LaboratoriesUnderwriters Laboratories Inc. is an independent product safety certification organization. Established in 1894, the company has its headquarters in Northbrook, Illinois. UL develops standards and test procedures for products, materials, components, assemblies, tools and equipment, chiefly dealing...
and Underwriters Laboratories of Canada (ULC). "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 ratingA fire-resistance rating typically means the duration for which a passive fire protection system can withstand a standard fire resistance test. This can be quantified simply as a measure of time, or it may entail a host of other criteria, involving other evidence of functionality or fitness for...
.
Fire testing of drywall assemblies for the purpose of expanding national catalogues, such as the
National Building Code of CanadaThe National Building Code of Canada is the model building code of Canada. It is issued by the Institute for Research In Construction ], a part of the National Research Council of Canada...
,
GermanyGermany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
's Part 4 of DIN4102 and its British cousin BS476, are a matter of routine
research and developmentThe phrase research and development , according to the Organization for Economic Co-operation and Development, refers to "creative work undertaken on a systematic basis in order to increase the stock of knowledge, including knowledge of man, culture and society, and the use of this stock of...
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 CanadaThe National Research Council is an agency of the Government of Canada which conducts scientific research and development.- History :...
routinely publishes 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
fastenerA fastener is a hardware device that mechanically joins or affixes two or more objects together.Fasteners can also be used to close a container such as a bag, a box, or an envelope; or they may involve keeping together the sides of an opening of flexible material, attaching a lid to a container,...
s holding the drywall. This typically results in
deflectionIn engineering, deflection is the degree to which a structural element is displaced under a load. It may refer to an angle or a distance.The deflection distance of a member under a load is directly related to the slope of the deflected shape of the member under that load and can be calculated by...
of the assembly towards the fire, as that is the location where the sublimation occurs, which weakens the assembly, due to the fire influence.
When tests are cosponsored, resulting in code recognized 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 UL Building Materials Directory) and that sufficient layers and thicknesses are used.
Fire testA fire test is a means of determining whether or not fire protection products meet minimum performance criteria as set out in a building code or other applicable legislation. Successful tests in laboratories holding national accreditation for testing and certification result in the issuance of a...
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,
penetrantPenetrants, or penetrating items, are the mechanical, electrical or structural items that pass through an opening in a wall or floor, such as pipes, electrical conduits, ducting, cables and cable trays, or structural steel beams and columns...
s do not follow the deflection movement of the drywall assemblies they penetrate. For example, see
cable trayIn the electrical wiring of buildings, a cable tray system is used to support insulated electric cables used for power distribution and communication. Cable trays are used as an alternative to open wiring or electrical conduit systems, and are commonly used for cable management in commercial and...
movement in a German test. It is, therefore, important to test
firestopA firestop is a passive fire protection system of various components used to seal openings and joints in fire-resistance rated wall and/or floor assemblies, based on fire testing and certification listings....
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
pipeWater pipes are pipes or tubes, frequently made of polyvinyl chloride , ductile iron, steel, cast iron, polypropylene, polyethylene, or copper, that carry pressurized and treated fresh water to buildings , as well as inside the building.-History:For many centuries, lead was the favoured material...
), 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. This is motion over and above that which is caused by the expansion of metallic penetrants, 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 steelStructural steel is steel construction material, a profile, formed with a specific shape or cross section and certain standards of chemical composition and mechanical properties...
. 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, which is independent of the assemblies penetrated, can be separately arranged.
North American market
North America is one of the largest gypsum board users in the world with a total wallboard plant capacity of 42000000000 square feet (3,901,927,680 m²) per year (world wide 85000000000 square feet (7,896,758,400 m²) per year). Moreover, the home building and remodeling markets in North America in the late 1990s and early 2000s increased demand. The gypsum board market was one of the biggest beneficiaries of the housing boom as "an average new American home contains more than 7.31 metric tons of gypsum."
The introduction in March 2005 of the Clean Air Interstate Rule by the
United States Environmental Protection AgencyThe U.S. Environmental Protection Agency is an agency of the federal government of the United States charged with protecting human health and the environment, by writing and enforcing regulations based on laws passed by Congress...
requires power plants to "cut sulfur dioxide emissions by 73%" by 2018. 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.
Waste
Because up to 17% of drywall is wasted during the manufacturing and installation processes and the drywall material is frequently not re-used, disposal can become a problem. Some landfill sites have banned the dumping of drywall. Some manufacturers take back waste wallboard from construction sites and recycle it into new wallboard. Recycled paper is typically 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 sodic clay and silt mixtures (
bay mudBay mud consists of thick deposits of soft, unconsolidated silty clay, which is saturated with water; these soil layers are situated at the bottom of certain estuaries, which are normally in temperate regions that have experienced cyclical glacial cycles...
), as well as using it in compost.
Types available in the USA and Canada
- Regular white board, from 1/4" to 3/4" thickness
- 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
Perlite is an amorphous volcanic glass that has a relatively high water content, typically formed by the hydration of obsidian. It occurs naturally and has the unusual property of greatly expanding when heated sufficiently...
, vermiculite and boric acidBoric acid, also called hydrogen borate or boracic acid or orthoboric acid or acidum boricum, is a weak acid of boron often used as an antiseptic, insecticide, flame retardant, as a neutron absorber, and as a precursor of other chemical compounds. It exists in the form of colorless crystals or a...
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. http://www.saint-gobaingyproc.in/plasterboard-gyproc-moisture-resistant.html
- Blueboard, blue face paper forms a strong bond with a skim coat or a built-up plaster finish providing both water and mold resistance.
- Cement board
A cement board is a combination of cement and reinforcing fibers formed into 4 foot by 8 foot sheets , 1/4 to 1/2 inch thick that are typically used as a tile backing board...
, 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 is a laminated drywall made with gypsum, other materials, and damping polymers to significantly increase the STC
- Mold-resistant, paperless drywall
- Enviroboard
Enviroboard is a construction panel, generally manufactured using compressed ecologically safe sourced material. Most often this means employing the use of agricultural waste fibres, such as the post-harvest straw of rice, barley, wheat, and elephant grass or alternatively, a more urban waste...
, 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
- Controlled density (CD), also called ceiling board, which is available only in 1/2" thickness and is significantly stiffer than regular white board.
- EcoRock, a drywall which uses a combination of 20 materials including recycled fly ash, slag, kiln dust and fillers and no starch cellulose; it is advertised as being environmentally-friendly due to the use of recycled materials and an energy efficient process.
- Gypsum “Firecode C.” This board is similar in composition to Type X, except for more glass fibers and a form of vermiculite, used to reduce shrinkage. When exposed to high heat, the gypsum core shrinks but this additive expands at about the same rate, so the gypsum core is more stable in a fire, and remains in place even after the gypsum dries up.
Common drywall tools
- Benches
A bench is a piece of furniture, on which several people may sit at the same time. Benches are typically made of wood, but may also be made of metal, stone, or synthetic materials. Many benches have arm and back rests; some have no back rest and can be sat on from either side. In public areas,...
- Chalk line
A chalk line or chalk box is a tool for marking long, straight lines on relatively flat surfaces, much farther than is practical by hand or with a straightedge....
- Corner trowel
A trowel is one of several similar hand tools used for digging, smoothing, or otherwise moving around small amounts of viscous or particulate material.-Hand tools:...
- Dimpler
- Drywall adhesive glue guns
- Drywall cart
- Drywall fastener
- Drywall (hatchet) hammer
- Drywall lifter
- Drywall jack
- Drywall screws and nails
- Electric screwdriver
A screwdriver is a tool for driving screws and often rotating other machine elements with the mating drive system. The screwdriver is made up of a head or tip, which engages with a screw, a mechanism to apply torque by rotating the tip, and some way to position and support the screwdriver...
- Keyhole saw
A keyhole saw is a long, narrow saw used for cutting small, often awkward features in various building materials...
or drywall router
- Pencil
- Surform
A surform tool features perforated sheet metal and resembles a food grater. A surform tool consists of a steel strip with holes punched out and the rim of each hole sharpened to form a cutting edge. The strip is mounted in a carriage or handle...
- Screw gun
Screw guns are similar to the power drill, at least in appearance. There are two basic types. Some screw guns are designed for drywall installation, some for general construction purposes. A drywall screw gun will turn as high as 4,000 RPMs, while a screw gun designed for larger screws and other...
- Stilts
Stilts are poles, posts or pillars used to allow a person or structure to stand at a distance above the ground. Walking stilts are poles equipped with steps for the feet to stand on, or straps to attach them to the legs, for the purpose of walking while elevated above a normal height...
- Stud finder
A stud finder is a handheld device used to determine the location of wood and metal framing studs used in light-frame construction after the walling surface has been installed....
- Tape measure
A tape measure or measuring tape is a flexible form of ruler. It consists of a ribbon of cloth, plastic, fiber glass, or metal strip with linear-measurement markings. It is a common measuring tool. Its flexibility allows for a measure of great length to be easily carried in pocket or toolkit and...
- Taping knife
A taping knife or joint knife is a drywall tool with a wide blade for spreading joint compound, also known as "mud". It can be used to spread mud over nail and screw indents in new drywall applications and is also used when using paper or fiberglass drywall tape to cover seams...
- T-square
- Utility knife
Levels of finish
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 their document about Levels of
Gypsum Board Finish. This document was created to "precisely describe" the desired finish of walls and ceilings prior to final decoration. This description enables contractors to better understand the requirements of architects and building owners and increase customer satisfaction. Specifications that include 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
GA-214-96 "Recommended Levels of Gypsum Board Finish".
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 that 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. 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.
Usage: Gloss and entirely non-textured surfaces.
Defective Chinese imports
There are reports that a substantial amount of defective drywall was imported into the United States from China and incorporated into tens of thousands of homes during rebuilding in 2006 and 2007 following Hurricane Katrina and in other places. Complaints include foul odor, health effects, and corrosion of metal within the structure. The same drywall was sold in Asia without problems resulting, but U.S. homes built much more tightly than homes in China, with less ventilation. A number of lawsuits are underway in many jurisdictions, but many of the sheets of drywall are simply marked, "Made in China", thus making identification of the Chinese manufacturer difficult. An investigation by the
Consumer Product Safety CommissionThe United States Consumer Product Safety Commission is an independent agency of the United States government created in 1972 through the Consumer Product Safety Act to protect "against unreasonable risks of injuries associated with consumer products." The CPSC is an independent agency that does...
, CPSC, was underway in 2009. In November 2009, the CPSC reported a "strong association" between Chinese drywall and corrosion of pipes and wires reported by thousands of homeowners in the United States. Further findings have shown that volatile sulfur compounds, including
hydrogen sulfideHydrogen sulfide is the chemical compound with the formula . It is a colorless, very poisonous, flammable gas with the characteristic foul odor of expired eggs perceptible at concentrations as low as 0.00047 parts per million...
, have been detected as emissions from the imported drywall and may be linked to health problems. Volatile sulfur compounds are emitted from many different types of drywall, and at least one investigation has pointed to high levels being emitted from drywalls manufactured in the United States.
See also
External links