Installs interior finishes (insulation, drywall, doors, trim, stairs and cabinetry)
Interior finish questions test control of air, vapour and sound before board goes on, then the quality of the visible work: flat drywall, tight joints, doors that latch, trim that fits, cabinets that are level and plumb.
Insulation and vapour control
Batt insulation is friction-fitted with no gaps or compressed corners and fills the full cavity. The vapour barrier goes on the warm side, is continuous over the whole envelope, and is sealed at laps, penetrations, and at the joint to foundation and ceiling. In a cold climate a gap or unsealed penetration becomes a condensation point. Attic insulation stays clear of the vent path and clear of heat sources such as light housings not rated for contact.
Drywall
Thickness follows the application: 12.7 mm is standard for walls, thicker or fire-rated board where a rating is required. Screws are set to dimple the paper without tearing it, closer together on ceilings and near edges than in wall fields. Joints are staggered, and the level of finish - from basic fire-taping to a fully skimmed level - is agreed before taping starts.
Doors, trim and cabinets
Pre-hung doors are set plumb and level, shimmed at hinges and strike, with an even reveal and no twist. Casing is coped at inside corners and mitred at outside corners, with the mitre back-cut so the outer edge closes. Cabinets start from a level line, are shimmed at floor and wall, fastened into framing or blocking, and scribed to the wall.
Worked example
Drywall for a room 4.0 m × 5.0 m with a 2.4 m ceiling. Walls: perimeter 18 m × 2.4 m = 43.2 m². Ceiling: 20 m². Total 63.2 m². A 1.2 m × 2.4 m sheet covers 2.88 m², so 63.2 ÷ 2.88 = 22 sheets; with 10 % for cuts and breakage, order 24. Deduct large openings only after the sheet layout is planned, because offcuts cannot always be reused.
Traps
Vapour barrier on the cold side or left unsealed at the rim; over-driven screws that break the paper; a door shimmed mid-jamb; and cabinets hung on drywall alone instead of blocking.