1800x900x12.5mm Square Edge Plasterboard 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 plaster. 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 technology made boards lighter and less brittle, then joint treatment materials and systems also evolved. A wallboard panel is made of a paper liner wrapped around an inner core made primarily from gypsum plaster.

The raw gypsum, (mined or obtained from flue-gas desulfurization (FGD)) must be calcined before use to produce the hemihydrate of calcium sulfate. This is done in kettle or flash calciners, typically using natural gas today. The plaster is mixed with fiber (typically paper and/or fiberglass), plasticizer, foaming agent, finely ground gypsum crystal as an accelerator, EDTA, starch or other chelate as a retarder, various additives that may increase mildew and/or fire resistance (fiberglass or vermiculite), wax emulsion or silanes 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.

In 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 250, 260, 270, 280, 300 cm and even longer(if ordered) are commonly available. Commonly used thicknesses of plasterboard available are 12.5 mm (modern equivalent of half an inch), typically used for walls, and 9.5mm exterior class, 13mm hard/durable type. and 15mm Fireboard's are commonly available. and also the 6.5mm thick "Rehab" type sheets. Plasterboard is commonly made with one of three 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, plain edge, used where the whole surface will receive a thin coating (skim coat) of finishing plaster, and finally bevelled on all four sides, used in products specialised for roofing. As an alternative to a week-long plaster application, an entire house can be drywalled in one or two days by two experienced drywallers, and drywall is easy enough to 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-square, by scoring the paper on the front side (usually white) with a utility knife, breaking the sheet along the cut, and cutting the paper backing. 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, glue, 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 labour expenses, to minimize call-backs due to truss uplift, to increase energy efficiency, and to make plumbing and electrical installation simpler. Drywall screws are designed to be self-tapping. 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 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. 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. 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 mud), as well as using it in compost.