A
- ABAA air barrier Air Barrier Assn. of America
- A continuous membrane or coating — fluid-applied, sheet, or self-adhered — required by most commercial envelope specs to block air leakage. On exterior drywall assemblies, the air barrier sits outboard of the DensGlass or equivalent sheathing. Drywall subs don't usually install it but need to know when their scope touches it, because missed sealant at penetrations becomes their callback.
- Abuse-resistant
- A classification of gypsum panels (per ASTM C1629) that resist surface indentation and penetration better than standard board. Common in corridors, classrooms, and healthcare. USG Fiberock Aqua-Tough and National Gypsum Hi-Abuse XP are the usual callouts. Priced 35–60% over standard board.
- ASTM C1396 Gypsum Panel Spec
- The master ASTM standard for gypsum wallboard. It covers dimensions, weights, core types, and performance. Every sheet of code-compliant drywall you buy is manufactured to this spec. When an architect writes "gypsum board complying with ASTM C1396," that's what they mean.
- ASTM C754 Steel Framing Install
- The installation standard for non-load-bearing cold-formed steel framing for gypsum panel applications. Covers stud spacing, fastener pull-out, bracing, and deflection. An AHJ who redlines your wall isn't quoting opinion — they're quoting C754.
- ASTM C840 Gypsum Install
- The installation standard for gypsum board — fastener spacing, joint offsets, panel orientation, and control-joint spacing. Read alongside GA-216 for finishing. C840 is what the inspector opens when they flag your screw pattern.
B
- Backer rod
- A compressible closed-cell foam rod sized to the joint width, used behind acoustic sealant or firestop at perimeter joints between drywall and adjacent substrates. Sized typically 3/8" to 3/4" OD. Forgetting backer rod at slab-to-deck joints is how fire-rated assemblies fail inspection.
- Bazooka Auto-taper
- A 60-inch cylindrical tool (TapeTech, Columbia, DEWALT FlatMaster) that dispenses tape and bedding mud simultaneously onto a joint. Doubles to triples the taping production rate of a skilled hand-taper. Runs about $1,800–$2,400 for the taper alone, or $6,500–$9,500 for a full kit with flat boxes and corner tools.
- Bead box
- A mud box tool used to apply compound to both flanges of a corner bead in one pass. Columbia and TapeTech make the common models. Pairs with paper-faced or tape-on metal bead. Cuts corner-bedding time roughly in half versus hand application.
- Bedding coat
- The first coat of joint compound, applied to the joint or corner bead to embed the tape. Bedding has to be thin and tight — too much mud under the tape and it floats off, too little and it won't bond. The whole finish rides on this coat being right.
- Bond plaster
- A thin base-coat plaster used over monolithic concrete or smooth CMU before veneer plaster or high-level skim. Not common on modern commercial, but you'll still see it on institutional and historical retrofits. Typical 1/16" application.
- Bull float (drywall use)
- A wide, long-handled float used to smooth large Level 5 skim-coat areas — lobbies, atrium walls. Borrowed from concrete work. Lets a single finisher keep a wet edge across a 10-foot wide surface before the skim starts setting.
C
- C-H stud
- A specialty stud profile shaped like a C with an H insert, used as the intermediate stud in shaftwall assemblies. The H receives 1-inch shaftliner board on one side and a double-layer of Type X on the other. You'll see it on elevator shafts and stair pressurization walls.
- CertainTeed board
- A major manufacturer of gypsum panels, sold under the ProRoc line. Residential 1/2" lightweight, commercial Type X, moisture-resistant, and abuse-resistant SKUs all available. Competes head-to-head with USG and Gold Bond.
- Chair rail reveal
- A horizontal reveal detail, typically 3/8" to 1/2" deep, cut into a partition at chair-rail height (32–36 inches). Handled with L-bead or a kerfed reveal bead (Trim-Tex Chamfer or similar). Slow to finish — budget 2–3× the LF rate of a plain joint.
- Channel Hat / Resilient / Furring
- Generic term for a horizontal C-shaped cold-formed member. Hat channel is used to fur out masonry walls. Resilient channel (RC-1 or RC-2) is spring-shaped, used to decouple drywall from framing for acoustic STC ratings. Furring channel is the flat version used on suspended ceilings.
- Cold-formed steel CFS
- Steel framing members roll-formed from light-gauge coil stock. Everything from 25-gauge partition studs to 16-gauge curtain-wall backup. SSMA (Steel Stud Manufacturers Association) publishes the standard profiles and limiting heights.
- Control joint CJ
- A prefabricated accessory (USG 093 or Trim-Tex 093) installed at regular intervals in long drywall runs to absorb structural movement. GA-216 recommends CJs at 30-foot max spacing on interior walls and ceilings, and at every building expansion joint. Skip them and the cracks tell on you.
- Corner bead
- The accessory that reinforces and finishes an outside corner. Three common types: galvanized metal (rigid, cheapest), paper-faced metal (Trim-Tex PFX or No-Coat), and vinyl. Paper-faced is the norm on commercial because it holds up better to impact and finishes cleaner.
- Cripple stud
- A short stud installed above a header or below a sill to support the panel between full-height studs. Standard at door and window framing. Spec-called at 16" or 24" OC depending on the base stud spacing.
D
- Deflection track
- A specialty top track with slotted or telescoping flanges that lets the structure above deflect without transferring load to the studs below. Required wherever a non-load-bearing partition meets a deflecting structure (deck, beam, truss). Common brands: ClarkDietrich MaxTrak, SCAFCO Deflection Track. Missing it at a truss is an inspection fail.
- DensArmor / glass-mat
- Georgia-Pacific's interior fiberglass-faced gypsum panel line. Same concept as a standard paper-faced panel, but with a fiberglass mat that resists mold and moisture better. Common in locker rooms, kitchens, and any wall that might see intermittent moisture.
- DensGlass
- GP's exterior-rated fiberglass-mat gypsum sheathing. Yellow or gold face, used outboard of studs as the structural sheathing layer beneath exterior cladding and air barrier. 5/8" Type X version is standard on fire-rated exterior assemblies.
- Dirty shop Abuse Test
- Slang for the ASTM C1629 abuse-resistance test classification. Labs hit the panel with a steel ball and measure indentation and penetration. A "Class 2" or "Class 3" panel has passed at progressively higher impact energies.
- Double-leg track
- A track with extended legs (typically 1-1/4" or 2" instead of the standard 1") used where tall studs need more lateral restraint before bracing. Common on 14-foot-plus interior partitions.
- Drywall axe
- A T-shaped tool combining a utility knife, tape measure, and straight edge into one handle. Lets a hanger mark and score a sheet in a single motion. DEWALT and Milwaukee both sell versions. Old-school hangers carry a separate T-square and knife and swear the axe is a gimmick; younger crews swear by it.
- Drywall T-square
- An aluminum 48-inch square with a crossbar that hooks the edge of a 4-foot-wide sheet. The primary cutting guide for scoring sheets. Stabila and Empire are the common brands. Bent T-squares make for crooked cuts — check them before every job.
E
- Eased edge
- A long edge of a gypsum panel with a slight rounding (about 1/16" radius) to reduce sanding ridges at butt joints. Different from a tapered edge — the eased edge is sometimes specified where a butt joint is unavoidable.
- Edge taper Tapered Edge
- The long edge of a standard gypsum panel, factory-beveled down about 1/16" to 1/8" over the last 2 inches. Creates a shallow trough at the joint that gets filled with tape and compound to form a flat finish. Butt ends (the cut short edges) have no taper, which is why butt joints are harder to finish.
F
- Fire-tape / Level 1
- Minimum finish per GA-214 for concealed areas — plenums, shafts, above ceilings. Tape is set in compound but no finish coats are applied. If the wall is behind a return air plenum, this is what the plans call. Budget about 0.006–0.009 labor hours per SF.
- Floating corner
- A framing detail at an interior drywall corner where the corner screws are omitted on one side to allow seasonal movement without cracking. Common in residential, rare in commercial with proper control joints.
- Furring channel
- A flat cold-formed Z or hat-shaped member used to suspend gypsum ceilings from a main runner or to fur out a masonry wall. DWC-25 and 1-1/2" hat are the common profiles. Spaced at 16" or 24" OC per the UL design.
G
- GA-214 Finish Levels
- The Gypsum Association's Recommended Levels of Gypsum Board Finish. Defines Levels 0 through 5. Level 1 is tape-set only; Level 5 is full skim coat. Every finish-level argument between architect, GC, and sub should end with both parties pulling up GA-214 and reading the actual definition.
- GP Gypsum Panel
- Industry shorthand on plans and takeoffs for "gypsum panel" — the actual drywall sheet. You'll see it alongside type and thickness: "5/8" Type X GP" means 5/8" Type X gypsum panel.
- Green board MR
- Moisture-resistant paper-faced gypsum panel, green-tinted face. ASTM C1396 section on moisture-resistant board. Appropriate for bathrooms, kitchens, laundry. Not appropriate as a tile substrate for wet areas — that's cement board or DensShield.
H
- Hand sander / Pole sander
- A rectangular sanding pad, typically 3-1/4" × 9-1/4", that clips around 120–220 grit sanding screens. The pole version screws onto a 4–8 foot pole for ceilings and upper walls. Hyde and Marshalltown are the common makers. Every finisher owns three.
- Hat channel Z-Furring
- A hat-profile cold-formed channel used to fur out masonry or concrete walls before applying drywall. Creates a stand-off space for insulation, vapor barrier, and electrical. 7/8" and 1-1/2" are the common depths.
- Header box
- A pre-fabricated steel assembly above a door or window opening, built from jack studs, king studs, a header, and cripples. Often prefabbed in the shop on repeat jobs (hotels, apartments) to save field hours.
- Hot mud Setting Compound
- Joint compound that hardens by chemical reaction rather than air-drying. Sold in powder form (USG Easy Sand 5, 20, 45, 90), mixed with water in a bucket, and has to be used within its set window. The number is the approximate working time in minutes. Harder to sand than ready-mix but dries faster in cold or humid conditions.
I
- IMPACT-X
- CertainTeed's abuse-resistant ProRoc panel line. Gypsum core reinforced with glass fibers. Meets ASTM C1629 Level 2 impact and abrasion. Common in schools, corridors, and healthcare — anywhere a gurney, shopping cart, or teenager will hit the wall.
J
- J-bead
- An L-shaped trim with a long leg that terminates drywall at a window jamb, ceiling, or other transition where the drywall ends cleanly. Open-nose (unfinished terminal) or closed-nose versions available. Different from L-bead in profile but often used interchangeably on spec sheets.
- Joint photographing
- When taped and finished joints become visible through paint under raking or critical light. Shows up as soft ghosts running across a wall. Caused by inadequate finish level (Level 4 where Level 5 was needed), uneven compound porosity, or primer-paint compatibility issues. The #1 reason a finisher gets called back on a lobby.
K
- KB-50
- Trim-Tex's expansion joint extrusion, often specified on long commercial walls and ceilings. Installed at 30-foot max spacing per GA-216. Also referenced on drawings as "093 expansion joint."
- Kerf (in reveal bead)
- The narrow slot cut into a reveal bead to receive the gypsum panel edge. The kerf dimension has to match the panel thickness — a 1/2" kerf bead will not seat a 5/8" panel. Architect's details sometimes get this wrong and it's caught in the shop drawing review.
L
- L-bead
- An L-shaped edge trim with one flange behind the drywall and one flange exposed as the finished edge. Used where drywall terminates against a dissimilar material — window frame, column, cabinet. Paper-faced versions (Trim-Tex 100) are easier to finish.
- Laser line
- A self-leveling cross-line or dot laser (DEWALT DW088LG, Bosch GLL, Leica Lino) used to lay out partition runs, set ceiling elevations, and align track. Has replaced the chalk line on most professional jobsites for layout.
- Level 5 skim coat
- Per GA-214, a thin coat of joint compound applied to the entire wall or ceiling surface — not just joints and fasteners. Required wherever gloss or semigloss paint is specified or where critical lighting will reveal surface imperfections. Adds 60–75% to the finishing labor over Level 4.
M
- MR board
- Short for moisture-resistant gypsum panel. Same as "green board." Paper-faced, moisture-resistant treated core. Not waterproof; not appropriate behind tile in a wet shower (use cement board or DensShield instead).
- Muffin
- Slang for a blob of dropped or squeezed-out mud sitting on the floor. Also describes what happens when a taper overloads a flat box and leaves a ring of mud at the tail of the joint. "Watch the muffins on four" is a foreman telling a taper to clean up their boxes.
P
- Pan head screw
- A self-drilling screw with a flat pan head used to fasten stud to track (frame-to-frame). Different from a drywall screw — a pan head is for steel-on-steel, a bugle head is for board-to-stud. Mixing them up leads to stripped heads and loose framing.
- Paper tape vs mesh tape
- Paper tape is stronger in tension and the standard for professional commercial joint finishing. Mesh tape is self-adhesive fiberglass — faster to apply but has less tensile strength and is easier to crack, especially at butt joints. Hot mud + mesh works; ready-mix + mesh is weaker. Pros use paper on everything except small repairs.
- Punch marks
- Small witness marks left on a wall by a GC or owner during a punch walk — blue painters tape, felt-tip dots, or stickers indicating spots that need touch-up. A clean punch walk has fewer than 40 marks per 10,000 SF of wall; a bad one has triple that.
R
- Rocking
- Field slang for hanging drywall. "Rocking the job" means installing the panels. A "rocker" is a hanger (specifically the one who carries the sheets and screws off). Doesn't refer to taping or finishing — those are separate trades.
S
- Scotty Scotch Head
- A flat-box extension handle attachment (Columbia, TapeTech) that allows a taper to run boxes overhead without a stilt or lift. The head pivots. Paired with a 42-inch or 48-inch extension pole.
- Screw gun clutch
- The adjustable clutch on a drywall screw gun (DEWALT DCF620, Milwaukee M18 Fuel, Senco DS) that disengages at a set depth so the screw head just dimples the paper without breaking it. A correctly set clutch is the difference between a fast, clean wall and a thousand popped screws to repair.
- Setting compound Hot Mud
- Joint compound that hardens chemically rather than drying. Sold as USG Easy Sand 20, 45, 90 or the Durabond series. The number is the approximate working time in minutes before it sets hard. 20-minute is common for first coats; 45 and 90 for wider joints and fill.
- Shaft wall CT Stud
- A rated wall assembly used around elevator shafts, mechanical chases, and stair pressurization. Uses a CT stud (C-H stud) with 1-inch shaftliner panels on one side and double Type X on the other, installed from one side only. Key UL designs: U415, U419, U465.
- Skim coat
- A thin, full-surface application of joint compound. Required for Level 5. Typically applied with a 12" or 14" knife or a flat box and then flat-troweled. Sometimes thinned with water ("slick mud") to improve workability.
- Slick mud
- Joint compound thinned slightly with water to make skim-coating faster and more uniform. Common finisher prep for Level 5. Too much water and the coat cracks when it dries; too little and it drags.
- Slitter
- A tool or accessory attachment that scores and cracks gypsum panels to a consistent rip width. Useful when a crew is cutting a lot of 12" or 24" strips — shaft-wall returns, window sills. Faster and straighter than freehand scoring with a utility knife.
- Stomp Ceiling Texture
- A ceiling texture applied by dipping a stomp brush into a thick mud mixture and stamping the surface. Leaves a swirled or spiky pattern. Common in older residential. On commercial it's usually replaced by orange peel or knockdown sprays from a Graco compressor rig.
- Sub-rail Casework Backing
- A run of 3/4" plywood or 16-gauge steel blocking installed between studs before drywall, used to catch screws for casework, handrails, grab bars, or wall-hung fixtures. Spec'd at specific heights and lengths in the details. Missed blocking = a callback when the millwork crew can't find solid backing.
- Suspended grid
- A metal grid hung from the structure above on wire hangers, used to support drywall ceilings (or ACT panels). For gyp ceilings, the grid is hat channel or furring channel. The grid carries the gyp; the wire carries the grid. Layout matters — unsupported spans exceeding the gauge limits will sag.
T
- Tape application roller
- A small hand roller used to embed tape firmly into the bedding coat. Prevents air bubbles, which turn into blisters after paint. Common on bazooka runs where speed sometimes leaves the tape proud.
- Taping knife 6/10/12
- The finishing knife, sold in progressive widths. 6-inch for bedding tape and fasteners, 10-inch for fill coats, 12-inch for finish coats. Marshalltown Blue Steel and Level5 are the standard professional brands. A taper typically owns all three.
- Texture Orange Peel / Knockdown / Popcorn
- Spray-applied surface finishes that hide Level 3–4 joint transitions. Orange peel is a light spatter; knockdown is sprayed heavy then partly flattened with a trowel; popcorn is a thick ceiling texture (being phased out on new work). Graco RTX series pumps are the common applicator. Texture is not a substitute for bad finishing — it amplifies some defects and hides others.
- Type X / Type C
- Fire-rated gypsum panel classifications. Type X is the standard fire-rated panel (most commonly 5/8", glass-fiber reinforced core). Type C is an enhanced version with more glass fiber and shrinkage-resistant additives — required on some UL designs (U419, U411) for longer ratings. Not interchangeable without checking the UL listing.
Z
- Z-furring
- A Z-shaped cold-formed member used to fur out masonry walls for insulation and drywall. The Z profile creates a standoff cavity that holds rigid insulation, and the outer leg receives the drywall. 1", 1-1/2", and 2" depths are common. Not the same as hat channel — the Z has an offset that makes it suited for insulation pockets.
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