Red Seal Drywall Finisher & Plasterer flashcards

36 cards. Read the term and the definition here. The deck at the top of this page is optional.

Silica exposure limit

US OSHA 29 CFR 1926.1153 sets an 8-hour TWA permissible exposure limit of 50 µg/m³ for respirable crystalline silica; Table 1 tasks specify engineering controls in place of air monitoring.

Hierarchy of controls

Ordered from most to least effective: elimination, substitution, engineering controls, administrative controls, and personal protective equipment. PPE is the last line of defence, not the first.

Lead paint presumption

Housing and child-occupied facilities built before 1978 are presumed to contain lead paint; any disturbance triggers lead-safe work practices, containment, and cleaning verification.

Fall protection threshold

In general construction, fall protection is required at 3 m (10 ft) or more above a lower level; scaffolds, ladders, and openings have their own specific requirements.

Setting compound set times

Setting-type joint compounds are labelled 20, 45, 90, or 210 minutes. They cure chemically rather than by drying, cannot be retempered after set, and shrink less than drying compounds.

Self-furring metal lath

Metal lath with dimples or ribs that hold the mesh away from the sheathing, creating a key space so plaster can wrap behind the mesh and lock into place.

Corner bead types

Nail-on, screw-on, paper-faced with laminated flanges, and bullnose. Paper-faced bead is preferred for straight corners because it resists cracking better than metal alone.

Screw spacing on ceilings

Single-layer board on ceilings uses screws at 300 mm (12 in) on center; fire-rated and water-resistant ceiling assemblies typically require 200 mm (8 in) on center.

Figured versus scaled dimensions

Written dimensions govern over measurements scaled from a drawing. Specifications and addenda generally govern over drawings, and large-scale details govern over small-scale plans.

Fire-resistance rating

A tested assembly rating in hours, such as 1 h or 2 h. Board type and thickness, fastener spacing, and joint treatment are all part of the tested system and cannot be substituted freely.

3-4-5 squaring method

A triangle with sides in the ratio 3:4:5 has a right angle between the two shorter sides. Used to square a room or establish perpendicular layout lines.

Finish level 5

A skim coat is applied over the entire gypsum board surface. Specified where gloss or semi-gloss paint and critical lighting will reveal joints, fasteners, and texture differences.

Framing tolerance for board

Studs should not deviate more than about 3 mm (1/8 in) from the plane of adjacent studs. Excess variation is shimmed or sistered before boarding to avoid wavy walls.

Backing at board edges

All unsupported board edges, including corners, ceiling perimeters, and opening jambs, require blocking or framing installed before the board is hung.

Substrate moisture content

Wood framing should be at or below 19% moisture content before boarding. Concrete and masonry must be dry and free of form release agents before plaster or adhesive.

Vapour barrier placement

In cold climates the vapour barrier goes on the warm side of the insulation. In mixed climates a vapour-retarder paint may substitute to allow some drying.

Screw penetration depth

Screws must penetrate wood framing at least 16 mm (5/8 in) or pass at least 10 mm (3/8 in) beyond a metal stud flange, with heads dimpled but not torn through.

Staggered board joints

Joints on opposite sides of a partition are offset from each other, and end joints are staggered between courses, to reduce cracking and improve fire and acoustic performance.

Water-resistant board limits

Water-resistant gypsum board suits tub and shower surrounds but is not a waterproof membrane. Shower pans, steam rooms, and wet floors require a separate waterproofing system.

Tape embedding

Paper tape is embedded in a thin bed of compound and excess is squeezed out. Bubbles and blisters must be cut out and re-taped rather than coated over.

Coat widening rule

Each successive joint compound coat extends about 50 mm (2 in) per side beyond the previous coat, producing a feathered edge that blends into the board surface.

Sanding between coats

Sand lightly between coats and remove dust. Over-sanding fuzzes the paper and exposes tape edges, which show as a halo under paint.

Raking light inspection

Inspecting finished joints under a light held at a shallow angle to the surface reveals ridges and hollows that are invisible under direct lighting.

Three-coat plaster sequence

Scratch coat, brown coat, and finish coat. The scratch coat is scored to key the brown coat, and the brown coat is floated to establish the plane.

Grounds and screeds

Wood or metal strips set at corners, openings, and floor lines to establish plaster thickness and plane. They act as guides for the straightedge and float.

Stucco curing

Portland cement stucco must be kept damp for at least 48 hours after each coat and protected from freezing. Rapid drying causes shrinkage cracking and weakens the coat.

Metal lath lapping

Lath laps at least 13 mm (1/2 in) at sides and 25 mm (1 in) at ends, fastened about 150 mm (6 in) on center. Correct lapping prevents cracks along seams.

Veneer plaster

A thin 2–3 mm (1/16–1/8 in) gypsum finish applied over a special base board. It cures hard and produces a monolithic surface with fewer joints than taped board.

Knockdown texture

Thinned joint compound is sprayed or rolled on, allowed to set partially, then flattened with a trowel. The result is a mottled, low-profile texture that hides surface imperfections.

Crown moulding spring angle

The angle between the back of the moulding and the wall, commonly 38° and 52°. It determines the mitre and bevel settings; a wrong setting produces open joints.

Weep screed clearance

A weep screed at the base of stucco provides drainage and must sit at least 100 mm (4 in) above grade or 50 mm (2 in) above paved surfaces.

Weather-resistive barrier laps

Building paper or house wrap is lapped at least 50 mm (2 in) and shingled so water drains outward and downward. Flashing must integrate with the barrier.

Stucco control joints

Control joints are spaced no more than about 3 m (10 ft) in each direction and are placed at changes in substrate, at opening corners, and at floor lines.

Plaster washers

Perforated washers screwed through existing plaster into framing to reattach areas that have lost their key, allowing repair without full removal of the plaster.

Lime versus gypsum plaster

Lime plaster is softer and more vapour-permeable than gypsum. Repairs on historic lime plaster should use compatible lime-based material to avoid trapping moisture.

Stain-blocking primer

Shellac or oil-based primer seals water stains and smoke odour before recoating. Water-based primers may not seal tannin or smoke odour adequately.