Gypsum Board and Panel Product Installation
Installation questions test product knowledge, fastener selection, joint layout, and compliance with fire- and sound-rated assemblies. Most marks are lost by treating every wall as generic.
Products
- Standard board, Type X (fire-rated core), improved Type C, moisture-resistant (MR), abuse-resistant, shaftwall liner, cement board, fiberglass-mat board, sound-deadening board and foil-backed board.
- Thicknesses of 12.7 mm, 15.9 mm, 19 mm and 25 mm; ceilings on 600 mm framing and most fire separations call for 15.9 mm.
- Never substitute a product in a rated assembly. The listed design controls board type and thickness, number of layers, fastener type and spacing, insulation, and perimeter details.
Installation rules
- Run board horizontally on walls to reduce butt joints and place the tapered edge at the joint; stagger joints between layers and between opposite sides of a wall.
- Fasteners: typical spacing is 300 mm (12 in.) in the field and 200 mm (8 in.) at edges and butt joints, with ceilings often closer; the rated design always governs. Set screws in a dimple, at least 10 mm from the board edge, without breaking the paper.
- Keep board about 13 mm off concrete floors and leave a small gap at dissimilar materials; fill the gaps before taping.
- Control joints are needed on long runs, commonly at intervals up to 9.1 m (30 ft), at changes of substrate, and where structure moves.
- On resilient channel, fasten only to the channel; a screw through to framing destroys the sound isolation.
Worked example
A garage/house separation is specified as a 1-hour assembly with 15.9 mm Type X on one side. The supplier delivers 12.7 mm regular board.
Reasoning: the rating comes from the tested design, not from the compound or paint. Substituting regular board lowers fire resistance and voids the assembly, so reject the delivery and obtain the specified Type X. Then confirm fastener length and spacing, insulation, and perimeter firestopping against the design before hanging.
Traps
Mixing board types on one job; overdriven screws that tear the paper; joints not landing on framing; butt joints without backing; skipping firestop at the top plate; boarding over recessed boxes without sealing.