Plaster and Gypsumboard Construction Terms

Joint Treatment. Concealing of gypsumboard joints, usually with tape and joint compound.
Butt. Joints in which gypsumboard ends with core exposed (usually in the direction of the board width) are placed together.
Crown (High or Hump). Protrusion of joint compound from gypsumboard surface at a joint.
Floating. (See Edges, Floating.)
Keenes Cement. A dead-burned gypsum product that yields a hard, high-strength plaster.
Sheet. A ply of gypsumboard attached to another ply with adhesive over the entire surface to be bonded.
Strip. A ply of gypsumboard attached to another ply by parallel strips of adhesive, usually 16 or 24 in apart.
Lath. A base to receive plaster.
Lime. Oxide of calcium produced by burning limestone. Heat drives out the carbon dioxide leaving calcium oxide, commonly termed quicklime. Addition of water to quicklime yields hydrated or slaked lime.
Lime Plaster. Base-coat plaster consisting essentially of lime and aggregate.
Lime Putty. Thick paste of water and slaked quicklime or hydrated lime.
Marezzo. An imitation marble formed with Keenes cement to which colors have been added.
Mud. (See Compounds.)
Nail Popping. Protrusion above the face of gypsumboard of a nail used to attach the board to framing; usually caused by shrinkage due to drying of inadequately cured wood framing.
Nail Spotter. A small, box-type applicator used to cover with joint compound the heads of nails in gypsumboard.
Neat Plaster. A base-coat plaster to which sand is added at the job.
Niche. A small recess in a wall.
Ogee. A curved section of a molding, partly convex and partly concave.
Calendered. Papers with a high glossy finish.
Cream (Ivory or Manila). Highly sized and calendered papers used as the face papers on gypsumboard.
Gray. Unsized, uncalendered papers used on the back side of regular gypsumboard and as the face and back papers of backing boards.

Sized. Paper treated with a sealant to equalize suction for paint and prevent rise of nap.
Perimeter Relief. A construction arrangement that permits building movements;
also denotes gaskets that relieve stresses at intersections of walls and ceilings.
Pinhole. A small hole that appears in a plaster cast because of excess water in preparation of the plaster; also denotes a small perforation in gypsumboard paper or paper joint tape.
Plasterboard. (See Gypsumboard.)
Prefill. An application method used in preparation of joints of tapered- or bevelededge gypsumboard to receive tape and joint treatment with the objective of reducing the possibility of ridging or beading.
Primer. A base coat of paint used to improve the bond and appearance of the finish coat of paint; usually referred to as an undercoat when tinted. (See also Sealer and Sizing.)
Punch out. A hole made in gypsumboard to fit closely around pipe that passes through the board.
Putty Coat. A smooth, troweled-finish coat containing lime putty and a gaging material.
Quicklime. (See Lime.)
Relief. Ornamental figures above a plane surface.
Retarder. Any material added to gypsum plaster that slows its set.
Return. The terminal of a cornice or molding that takes the form of an external miter and stops at the wall line.
Reveal. The vertical face of a door or window opening between the face of the interior wall and the window or door frame.
Ridging. A linear surface protrusion along treated joints.
Ripper. A narrow strip of gypsumboard used for soffits, window reveals, and finished openings.
Runner. A metal or wood track or strip placed at floor and ceiling to receive framing members for partitions.
Sanding. Smoothing a joint treatment for gypsumboard with sandpaper. In wet sanding, the joint is smoothed with a coarse wet sponge, so that less dust is produced than in dry sanding.
Scagliola. An imitation marble, usually precast, made with Keenes cement.
Score. A groove cut in the surface of a board with a sharp blade to expedite manual breaking of the board.
Scratch Coat. First coat of plaster in three-coat work.
Screeds. Long, narrow strips that serve as guides for plastering; also denotes tools, such as straightedges, used to shape an unhardened surface.
Sealer. A base coat of paint used to seal a surface and equalize differences in surface suction, to improve the bond and appearance of the finish coat. (See also Primer and Sizing.)
Seam. A treated gypsumboard joint.
Sheathing, Gypsum. A gypsumboard formulated for use as an enclosure for an exterior wall and a base for siding or other exterior facings, but not intended for long-time direct exposure to the weather.

Ship Lap. An offset lamination of two layers of gypsumboard.
Shoulder. The area between the tapered edge and the face of a gypsumboard.
Sizing. A surface sealant used to equalize suction of paint when applied to gypsumboard paper and prevent rising of the nap.
Skim Coat. (See Finish Coat.)
Skip Trowel. A method of texturing a surface that results in a rough Spanish
Stucco effect.
Slaking. Adding water to hydrate quicklime into a putty.
Soffit. The underside of an arch, cornice, bead, or other construction.
Soffit Board. A gypsumboard formulated for use on the underside of exterior overhangs, carport ceilings, and other areas protected from the weather.
Splay Angle. An angle of more than 90.
Spray Texture. A mechanically applied material, which may contain aggregates to produce various effects, used to form decorative finishes.
Staff (Casts). Plaster casts made in molds and reinforced with fiber; usually wired or nailed into place.
Stucco. Plaster applied to the exterior of a building.
Substrate. A surface capable of receiving additional finish or decoration; also denotes the base or concealed layer of gypsumboard in a composite assembly.
Suspension System. Construction, usually incorporating heavy-gage hanging wire, for supporting a ceiling set below structural floor framing, roof, subfloor, or floor deck.
Sweat out. A soft, damp wall area of plaster caused by poor drying conditions.
Swirl Texturing. A method of applying texturing material in a decorative circular pattern.
Dry. A tape applied over gypsumboard joints with adhesive other than conventional joint compound.
Joint. A paper tape or fiber mesh for reinforcing joint compound to conceal and reinforce the joints of gypsumboard.
Tape Creaser. A hand-held tool for folding joint tape for use in reentrant corners.
Temper. Mixing of plaster to a workable consistency.
Template. A gage, pattern, or mold used as a guide to produce arches, curves, and various other shapes.
Veneer Plasters. Gypsum plasters meeting requirements of ASTM C587, and that may be applied in one or more coats to a maximum thickness of 1⁄4 in.
Wadding. The act of hanging staff by fastening wads made of plaster of paris and excelsior or fiber to the casts and winding them around the framing.
Wainscot. The lower 3 or 4 ft of an interior wall when it is finished differently from the remainder of the wall.
Gypsum. A gypsumboard used primarily as an interior surface.
Laminated. Two or more layers of gypsumboard held together with an adhesive.

Predecorated. A gypsumboard with a finished surface, such as paint, texturing material, vinyl film, or printed paper coverings, applied before the board is delivered to the building site.
White Coat. A gaged lime-putty troweled-finish coat.

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