Trade Sequence for a Build-Under

The order trades work in on an owner-builder project is not flexible, and getting it wrong means paying trades to undo and redo work. Understanding the sequence before you start is one of the most important pieces of preparation you can do.

Process current as at 2026. Trade availability, certifier hold-point requirements and lead times may have shifted since this article was last reviewed. The sequencing logic itself is durable; the Brisbane market context is point-in-time. Confirm current requirements with your certifier and trades before relying on any specific timing detail. Where this article describes “what we did”, that experience is from our Coorparoo project.

Why sequence matters

Certain trades must complete their work before others can begin. Electrical rough-in must happen before plasterboard, waterproofing before tiling and the slab pour before framing. The sequence is enforced both by practical necessity and by inspection hold points, the stages at which the certifier must inspect and sign off before the next stage can proceed. If you board over rough-in services before the certifier has inspected them, you will be asked to remove the plasterboard.

The sequence for a Queenslander build-under

Stage 1: Raise and subfloor

1. Structural engineering (design and documentation)
2. Pre-raise preparation (services disconnection, temporary bracing)
3. Raise day (contractor raises the house to target height)
4. Temporary supports installed
5. Certifier inspects temporary works
6. Permanent subfloor installation (stumps, bearers, joists)
7. Certifier inspects subfloor frame before house is lowered
8. House lowered onto permanent subfloor
9. Services reconnected

Stage 2: Slab

1. Earthworks (excavation, bulk fill, compaction)
2. Services rough-in under slab (drainage, water, electrical conduits if applicable)
3. Termite barrier installation
4. Reinforcing steel placement
5. Hold point: certifier inspects slab reinforcing and drainage before concrete pour
6. Concrete pour
7. Slab cure (typically 28 days to full strength - framing can begin at 7-14 days with engineer approval)

Stage 3: Framing

1. External wall framing (perimeter walls)
2. Internal wall framing (non-load-bearing partitions)
3. New roof sections (garage, carport) if applicable
4. Hold point: certifier inspects frame before any lining commences

Stage 4: Rough-in services (concurrent with and following framing)

1. Electrical rough-in (cables run to all switch, outlet and light positions)
2. Plumbing rough-in (water supply, drain lines, gas if applicable)
3. HVAC rough-in (ductwork, refrigerant lines)
4. Hold point: certifier inspects rough-in services and collects compliance certificates from each trade before walls are closed

Stage 5: Insulation, windows, external cladding

1. Wall insulation installed
2. Ceiling insulation installed
3. Windows and external doors installed
4. External cladding installed
5. Wet area waterproofing membranes installed
6. Hold point: certifier inspects insulation continuity, wet area membranes before lining

Stage 6: Linings

1. Plasterboard installed (hang, set, sand)
2. Cornices and stopping

Stage 7: Fit-out (in sequence)

1. Bathroom and laundry tiling
2. Bathroom and laundry fit-off (vanities, toilets, showers)
3. Flooring (polished concrete, tiles or floor coverings - depends on type)
4. Painting (internal, ground floor)
5. Electrical fit-off (GPOs, switches, light fittings, switchboard)
6. Plumbing fit-off (tapware, basins, laundry connections)
7. HVAC commissioning

Stage 8: Final

1. Final clean
2. As-built documentation compiled
3. Hold point: certifier final inspection
4. Form 21 (Occupancy Certificate) issued

Common sequencing mistakes

Installing plasterboard before the rough-in inspection. This is the most common and costly mistake. Always confirm the certifier has inspected before boarding.

Tiling before waterproofing is signed off. The certifier needs to see the membrane before it’s covered by tiles.

Booking flooring before painting. If you paint after the floors go in, you will get paint on the floors. Sequence painting before flooring.

HVAC ductwork after plasterboard. Duct penetrations in ceilings must be coordinated with ceiling frames before boarding. Late HVAC bookings are a common source of delay.