- Type X board
- Gypsum panel with a denser, glass-fiber-reinforced core made to hold up longer in a fire. It is the basic building block of rated partitions and ceilings, where layers and joints must follow the assembly that was tested.
- Runner track
- U-shaped steel channel fastened along the floor and ceiling to receive the ends of studs. Its alignment sets the wall location, so layout lines are snapped for it before any studs are cut.
- Steel thickness in mils
- The base metal of a stud or track measured in thousandths of an inch, an alternative to the gauge number. It controls which screw point can penetrate and whether the framing is thick enough to count as structural.
- Bugle-head screw
- A drywall screw with a flared head that sinks into the paper face without tearing it. A sharp point suits thin steel, while thicker framing needs a self-drilling tip, so the length and point are matched to the stud.
- Membrane penetration
- Any opening cut through one face of a fire-rated wall, such as an electrical box. Each one weakens the protective layer, so rules limit box size, keep boxes on opposite sides apart and call for sealing.
- Putty pad
- A moldable fire-stopping pad wrapped around the back of an electrical box in a rated wall. It swells and insulates when heated, helping the wall keep its rating where a box has been cut in.
- Staggered joints
- Board seams placed so they do not line up from one layer to the next or across the two sides of a partition. Offsetting them stops a single crack or fire path from running straight through the wall.
- Level of finish
- A numbered scale describing how much joint and surface treatment a drywall job receives, from raw board to a full skim coat. The specified level depends on what will cover it and how harsh the lighting will be.
- Setting-type compound
- Powdered joint compound mixed with water that hardens by chemical reaction, in a time printed on the bag. It shrinks little, so it fills gaps and bonds tape well, and the next coat can follow once it sets.
- Embedding coat
- The first layer of compound spread over a joint with tape pressed into it. It bonds the tape to the board and must be wiped tight, since air pockets or too little mud under the tape cause bubbles and cracks.
- Feathering
- Spreading each coat of compound progressively wider and thinner at its edges so the joint blends invisibly into the board. Wide, light feathering is what makes finished walls look flat under side lighting.
- Corner bead
- Metal or vinyl trim fastened to an outside corner to protect it from impact and give a straight edge. Compound is applied over its wings, which must be fastened firmly and never left proud of the board.
- Control joint
- A deliberate break in a long wall or ceiling surface, formed with a special trim, that lets the building shift or expand without cracking the board. It must be located per the standard and not covered with ordinary tape.
- Resilient channel
- A thin metal strip with a flexible leg fastened across studs or joists so the board floats slightly off the framing. It reduces sound transfer, but screws driven through into the framing can defeat the effect.
- Gypsum board diaphragm
- A ceiling or wall of gypsum board fastened with nails or screws on a prescribed pattern so it can resist lateral loads. In that role it follows structural tables and cannot be installed as ordinary decorative board.
- Backing
- Extra wood or metal installed between studs so heavy items such as grab bars, cabinets and handrails have solid fastening points. It must be in place and located on the plans before the board covers the wall.
- Rated wall marking
- Lettering or labels placed on fire-rated walls where they are visible in attics and above ceilings. They tell later trades that the wall is a barrier and that openings through it must be protected.
- Skim coat
- A thin, overall layer of compound troweled across an entire surface to even out its texture and seam lines. It is the way to reach the highest finish level and is used before gloss paint or raking light.
- Knockdown texture
- A spattered compound pattern flattened lightly with a broad knife while still wet. It hides minor imperfections and gives a mottled, low-relief surface, and the mix thickness and spray settings control its look.
