page_title: Drywall
section_title: Construction techniques
hierarchical_section_title: Drywall / Construction techniques
caption_attribution_description: English: Lucedale, Miss., 25 May, 2006 -- Church of the Brethern volunteers, Bill Neville (left) and Bob Sunday, complete sheetrock work on a home damaged by Hurricane Katrina. Both men traveled from Middle Pennsylvania to help with the rebuilding efforts. Michelle Miller-Freeck/FEMA.
context_page_description: Drywall is a panel made of calcium sulfate dihydrate, with or without additives, typically extruded between thick sheets of facer and backer paper, used in the construction of interior walls and ceilings. The plaster is mixed with fiber, plasticizer, foaming agent, and various additives that can reduce mildew, flammability, and water absorption.
  In the mid-20th century, drywall construction became prevalent in North America as a time and labor saving alternative to traditional lath and plaster.
context_section_description: 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 be installed by many amateur home carpenters. In large-scale commercial construction, the work of installing and finishing drywall is often split between drywall mechanics, or hangers, who install the wallboard, and tapers and mudmen, or float crew, who finish the joints and cover the fastener heads with drywall compound. Dry wall can be finished anywhere from a level 0 to a level 5, where 0 is not finished in any fashion and 5 is the most pristine. Depending on how significant the finish is to the customer the extra steps in the finish may or may not be necessary, though priming and painting of drywall is recommended in any location where it may be exposed to any wear.
  Drywall is cut to size, using a large T-square, by scoring the paper on the finished 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 structure with nails or drywall screws and often glue. 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 saves material and labour cost, to minimize call-backs due to truss uplift, to increase energy efficiency, and to make plumbing and electrical installation simpler.
  When driven fully home, drywall screws countersink their heads slightly into the drywall. They use a 'bugle head', a concave taper, rather than the conventional conical countersunk head; this compresses the drywall surface rather than cutting into it and so avoids tearing the paper. Screws for light-gauge steel framing have an acute point and finely spaced threads. 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.
  After the sheets are secured to the wall studs or ceiling joists, the installer conceals the seams between drywall sheets with 'joint tape' and several layers of 'joint compound' (sometimes called 'mud'), typically spread with a taping knife or putty knife. 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.
caption: Applying 'joint compound' to drywall.
exif: {"Image ImageDescription": "Lucedale, Miss., 25 May, 2006 -- Church of the Brethern volunteers, Bill Neville (left) and Bob Sunday, complete sheetrock work on a home damaged by Hurricane Katrina.  Both men traveled from Middle Pennsylvania to help with the rebuilding efforts.  Michelle Miller-Freeck/FEMA.", "Image Make": "NIKON CORPORATION", "Image Model": "NIKON D70", "Image Orientation": "Horizontal (normal)", "Image XResolution": "300", "Image YResolution": "300", "Image ResolutionUnit": "Pixels/Inch", "Image Software": "Adobe Photoshop CS Windows", "Image DateTime": "2006:05:26 16:11:42", "Image YCbCrPositioning": "Co-sited", "Image ExifOffset": "516", "Thumbnail Compression": "JPEG (old-style)", "Thumbnail XResolution": "72", "Thumbnail YResolution": "72", "Thumbnail ResolutionUnit": "Pixels/Inch", "Thumbnail JPEGInterchangeFormat": "1210", "Thumbnail JPEGInterchangeFormatLength": "4243", "EXIF ExposureTime": "1/200", "EXIF FNumber": "71/10", "EXIF ExposureProgram": "Program Normal", "EXIF ExifVersion": "0221", "EXIF DateTimeOriginal": "2006:05:23 21:48:09", "EXIF DateTimeDigitized": "2006:05:23 21:48:09", "EXIF ComponentsConfiguration": "YCbCr", "EXIF CompressedBitsPerPixel": "4", "EXIF ExposureBiasValue": "0", "EXIF MaxApertureValue": "37/10", "EXIF MeteringMode": "Pattern", "EXIF LightSource": "Unknown", "EXIF Flash": "Flash fired, auto mode, return light detected", "EXIF FocalLength": "31", "EXIF SubSecTime": "00", "EXIF SubSecTimeOriginal": "00", "EXIF SubSecTimeDigitized": "00", "EXIF FlashPixVersion": "0100", "EXIF ColorSpace": "sRGB", "EXIF ExifImageWidth": "3000", "EXIF ExifImageLength": "2400", "EXIF SensingMethod": "One-chip color area", "EXIF FileSource": "Digital Camera", "EXIF SceneType": "Directly Photographed", "EXIF CVAPattern": "[0, 2, 0, 2, 2, 1, 1, 0]", "EXIF CustomRendered": "Normal", "EXIF ExposureMode": "Auto Exposure", "EXIF WhiteBalance": "Auto", "EXIF DigitalZoomRatio": "1", "EXIF FocalLengthIn35mmFilm": "46", "EXIF SceneCaptureType": "Standard", "EXIF GainControl": "Low gain up", "EXIF Contrast": "Normal", "EXIF Saturation": "Normal", "EXIF Sharpness": "Normal", "EXIF SubjectDistanceRange": "0"}