Residential — Alterations & Additions

Two or more storeys require a full perimeter scaffold

At two storeys and above the work platform exceeds 4m, which mandates a licensed scaffold with a working deck per level rather than trestles. Scaffold face area is perimeter × wall height × storeys, so a double-storey job carries roughly double the scaffold area of a single-storey job of the same footprint, plus a longer hire period.

Two or more storeys require suspended floor structure and a stair

Suspended floor framing, floor insulation and a stair only exist above one storey. Two-storey construction adds 15–20% to the base rate per m², covering these plus the additional steel and more complex structural engineering.

Precast, portal frame and truss erection require a crane

Panel and portal erection cannot proceed without lifting plant.

Renovation requires protection of retained structure and finishes

Work adjacent to occupied or retained fabric carries protection, propping and make-good costs that do not exist on a greenfield build. Make-good is the line item most often missed in renovation estimates.

Pre-1990 buildings require a hazardous materials survey

Asbestos and lead paint must be identified before demolition on any building that predates 1990. The survey is priced; removal is normally excluded and carried as a provisional sum because the extent is unknowable until the survey is done.

Lightweight wall systems allow a reduced footing design

A wall system under half the dead load of brick veneer can permit a lighter slab and footing design on reactive clay. On Melbourne Class H sites this saving frequently exceeds the panel premium — worth checking against the structural engineer before assuming the brick footing design.