The slab
The slab category cost $37,900: a 112.5 m² raft slab on Coorparoo shale, with deep edge beams to handle the variable ground conditions. That figure covered earthworks, the termite barrier, formwork, steel and the concrete pump. The shale variability added a $2,200 variation on one corner.
Subfloor framing
Subfloor framing went in at $18,000, costed inside the raise-and-subfloor category, once the stumps were set and the slab had cured. Coordination with the engineer and certifier matters most through this stage, because hold points sit between framing and the next inspection.
Posts and bracing
The original Queenslander posts were assessed, retained where structurally sound and replaced where needed. Engineering specified the bracing pattern across the new lower level. Modern bracing standards on a 100-year-old structure demand engineering work that stays hidden in the budget until the certifier flags it.
Engineering hold points
Engineering hold points sit across the whole structural sequence: slab, subfloor frame, wall frame and roof tie-down. Each one needs a certifier inspection and engineer sign-off before the next trade arrives. Missing a hold point costs about a week.
