Carpentry and Structural Support
This domain tests the carpentry support work that carries loads safely: layout and framing, headers and beams, joist installation, sheathing, temporary bracing, and shoring existing structure during renovation. Expect questions on load path, span tables, notching and boring limits, fasteners, and truss bracing.
Layout and framing
- Establish lines from the drawings, check them against a diagonal, and snap lines for plates.
- Studs are commonly spaced at 400 mm or 600 mm on centre, matching sheathing and insulation modules.
- Openings need king studs, jack studs, and a header sized from the span table or engineer's design; do not guess a header size.
- Maintain the load path from roof to foundation: beams bear on posts or walls, posts bear on footings, and joists bear on beams or walls with the specified bearing length.
Joists, blocking, and bracing
- Install joist hangers with the manufacturer's specified fasteners; ordinary screws or short nails do not substitute for hanger nails.
- Add blocking and bridging where specified, and install fire blocking between floors and at concealed spaces as required.
- Brace roof trusses temporarily per the truss drawings before loading them; trusses are unstable until braced and sheathed.
- Use preserved wood where specified and match fasteners and flashing to the treatment; cut ends are treated per the manufacturer.
Renovation and shoring
- Before removing a wall, confirm whether it is load-bearing from drawings and an engineer's assessment.
- Install temporary shoring on both sides where required, with posts on solid footings and the load transferred progressively.
- Backfill and remove shoring in the reverse sequence, after the permanent structure is complete.
Worked example
A renovation requires opening a 3 m span in a basement bearing wall. The crew checks the drawings, confirms the wall carries floor joists above, and calls for an engineered beam and post design. Temporary stud walls with posts are built on each side and shimmed tight. The permanent beam is installed, posts are set on concrete pads sized for the load, and the temporary shoring is removed only after the beam is fully connected and the connections are inspected.
Traps that cost marks
- Assuming a wall is non-bearing because it looks thin.
- Using a header or beam size that was never designed for the span.
- Notching or boring joists beyond the permitted limits.
- Removing shoring before the permanent load path is complete.