Red Seal Lather (ISM) flashcards

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

Fall protection height

In most Canadian jurisdictions, fall protection is required when working at heights of 3 metres (10 feet) or more. This includes guardrails, safety nets, or personal fall arrest systems.

WHMIS 2015

Workplace Hazardous Materials Information System requires supplier labels and safety data sheets (SDS) for controlled products, and worker training on their safe use and handling.

Scaffold platform width

Scaffold platforms must be at least 460 mm (18 inches) wide and equipped with guardrails including top rail, mid rail, and toe board to prevent falls and falling objects.

Ladder setup angle

A ladder should be set at a 1:4 ratio (75-degree angle), meaning for every 4 units of height, the base is 1 unit from the wall. It must extend 1 metre above the landing.

NBC fire-resistance rating

Fire-resistance ratings are expressed in hours (e.g., 1 hour, 2 hours) and are achieved by specific assemblies listed in the National Building Code or manufacturer listings.

STC 50 requirement

The National Building Code requires a Sound Transmission Class (STC) rating of at least 50 for party walls between dwelling units to reduce airborne sound transmission.

Vapour barrier permeance

In cold climates, a vapour barrier with a permeance of 0.15 perm (8.5 ng/(Pa·s·m²)) or less is typically required on the warm side of the insulation, as per code.

Drawing line conventions

On architectural drawings, dashed lines often indicate objects above the cut plane (e.g., a soffit), while solid lines show visible objects. Always refer to the legend for symbols.

Steel stud spacing

Interior steel studs are typically spaced at 400 mm (16 inches) or 600 mm (24 inches) on centre, depending on gypsum board thickness and required fire-resistance rating.

Suspended ceiling hanger spacing

Hanger wires for suspended ceilings must be 12-gauge galvanized steel, spaced at maximum 1200 mm (4 feet) on centre along main runners, and within 150 mm (6 inches) of ends.

Resilient channel orientation

Resilient channels are installed perpendicular to studs and spaced at 400 mm (16 inches) or 600 mm (24 inches) on centre to decouple gypsum board and improve acoustics.

Control joint spacing

Control joints in gypsum board ceilings are required at maximum 9.3 square metres (100 square feet) per joint and at intervals not exceeding 9.1 metres (30 feet).

Gypsum board finish levels

Joint compound finish levels range from Level 1 (for plenum areas) to Level 5 (for glossy paint under critical lighting). Level 4 is standard for most residential walls.

Stucco coat thicknesses

Three-coat stucco consists of a scratch coat 10 mm (3/8 in), a brown coat 6 mm (1/4 in), and a finish coat 3 mm (1/8 in), for a total thickness of at least 19 mm (3/4 in).

Acoustic panel acclimatization

Lay-in acoustic ceiling panels must be acclimatized to room temperature and humidity for at least 24 hours before installation to prevent warping and ensure proper fit.

Corner bead fastener spacing

Corner bead is installed on external corners of gypsum board and fastened at maximum 150 mm (6 inches) on centre to provide a straight, reinforced corner.

Gypsum board thicknesses

Common gypsum board thicknesses are 6.4 mm (1/4 in), 9.5 mm (3/8 in), 12.7 mm (1/2 in), 15.9 mm (5/8 in), and 19 mm (3/4 in). 12.7 mm is standard for walls.

Screw spacing on ceilings

When installing gypsum board on ceilings, screws are spaced at maximum 300 mm (12 inches) on centre; on walls, maximum 400 mm (16 inches) on centre.

Fire-rated assembly matching

For fire-rated assemblies, the type and spacing of fasteners, the type of gypsum board (e.g., Type X), and joint treatment must exactly match the listed ULC design.

Sheathing expansion gap

Plywood or OSB sheathing must be installed with a 3 mm (1/8 inch) gap between panels to allow for expansion and prevent buckling.

Vapour barrier placement

In cold climates, the vapour barrier is installed on the warm side of the insulation (interior side). In Canada, 0.15 mm (6 mil) polyethylene is commonly used.

Air barrier continuity

The air barrier must be continuous across the building envelope, including at penetrations, joints, and intersections, and must be sealed with compatible sealants or tapes.

Batt insulation compression

Compressing batt insulation reduces its R-value. For example, compressing a nominal R-12 batt by 50% can reduce its R-value by nearly half.

Vapour barrier sealing

All seams and penetrations in the vapour barrier must be sealed with approved tape or acoustical sealant, including at the perimeter and at electrical boxes.

Metal lath weight

Diamond mesh metal lath is available in weights of 1.75 lb/yd² and 2.5 lb/yd². It must be fastened to framing at maximum 150 mm (6 inches) on centre.

Plaster basecoat thickness

For gypsum plaster, a basecoat of 10 mm (3/8 inch) is applied over lath, followed by a finish coat of 3 mm (1/8 inch).

Stucco curing time

Stucco must be moist-cured for at least 48 hours after the scratch coat and 48 hours after the brown coat to allow proper hydration and prevent cracking.

Scratch coat scoring

The scratch coat of stucco must be scored with horizontal lines to provide a mechanical key for the brown coat to bond to.

Powder-actuated tool safety

Only trained and certified operators may use powder-actuated tools. Wear eye and hearing protection, and never use them in an explosive atmosphere.

Screw gun depth setting

Adjust the depth setting on a drywall screw gun so the screw head dimples the paper without breaking it. Replace worn bits regularly for consistent results.

Mixing plaster speed

When mixing plaster or joint compound, use a heavy-duty drill with a mixing paddle at low speed to avoid air entrainment. Allow the mix to slake before final mixing.

Gypsum board waste factor

When estimating gypsum board, calculate total square footage and divide by sheet area (e.g., 32 sq ft for 4x8 sheet). Add 10% for waste and cuts.

Joint compound estimation

Approximately 1 kg (2.2 lb) of joint compound is needed per 1 square metre (10.8 square feet) of gypsum board for a Level 4 finish.