Ground-floor extension or addition, standard finish (per m²) Two Illawarra builders publishing their own numbers, both fetched 31 August 2026. Adlington Homes, which states that the figures reflect its own projects rather than a generic cost guide, gives $2,800-$3,800/m² for a standard ground-floor addition and $3,800-$5,000/m² at the high end (page dated 26 August 2026). Modern View Constructions gives $2,500-$4,200/m² for standard finishes, attributing it to industry pricing guides for 2026 (page dated 28 July 2026). The row takes the union. Neither publisher runs city pages outside the Illawarra, so there is no sibling-city table to compare against; the check applied instead was whether the figures are a national average republished locally, and both are framed as regional with different bands. | A$2,500 — A$4,200 |
Second-storey addition (per m²) Same two Illawarra sources, fetched 31 August 2026. Adlington Homes gives $3,500-$4,800/m² for a standard second-storey addition and $4,800-$5,500+/m² at the high end; Modern View Constructions gives $3,500-$5,500+/m², describing a second storey as roughly 30-40% more than a ground-floor addition. Both bands start at the same figure and end within $700 of each other, which is why the row runs $3,500-$5,500. Anything carrying a plus sign at the top is the publisher's own signal that the ceiling is not a ceiling. | A$3,500 — A$5,500 |
Custom new home — whole project Evolution Building Group, a Wollongong builder, publishes its own project range for the Illawarra (page dated 12 June 2026, fetched 31 August 2026): $700,000-$900,000 for a well-specified single-storey home on a manageable site, $900,000-$1,300,000 mid-range including split-level designs, and $1,300,000-$2,000,000 for premium specification, complex sites and coastal or escarpment locations. The same page declines to give a per-m² rate, stating that rates are not reliable when site conditions and specification move independently of floor area — which is why no per-m² figure for new builds appears on this page either. | A$700,000 — A$2,000,000 |
Sloping or escarpment block — extra site cost on top of the build The same Evolution Building Group page (fetched 31 August 2026) states $50,000 to $200,000 or more in additional cost where a block needs cut and fill, a split-level structure or retaining walls. It is one builder's own figure rather than a market survey, and the open top end is the publisher's. It is listed separately because it is the item most often missing from a comparison between two quotes on the same design: the same house on two Wollongong blocks is not the same project. | A$50,000 — A$200,000 |
Full bathroom renovation Two Illawarra trade sources, both fetched 31 August 2026. HBN Constructions publishes Illawarra guide ranges marked guide only, not a quote: $12,000-$18,000 for a refresh keeping the layout, $18,000-$28,000 for a strip-out and rebuild with mid-range fixtures and floor-to-ceiling tiling, $28,000-$45,000+ where the layout changes or plumbing is relocated. All Round Carpentry (page dated 8 June 2026) puts the Illawarra range at $15,000-$35,000 overall, with a budget refresh at $12,000-$18,000 and mid-range at $20,000-$30,000. The two agree closely at the bottom and differ at the top, so the row runs to the higher ceiling. | A$12,000 — A$45,000 |
Approval pathway — CDC or DA lodgement and certification fees Adlington Homes itemises the pre-construction costs for an Illawarra project (page dated 26 August 2026, fetched 31 August 2026): complying development certificate approval $3,000-$6,000, development application approval $5,000-$15,000+, structural engineer $3,000-$8,000, survey and reports $2,000-$5,000, design fees $8,000-$25,000. This row covers the approval line only, because that is the one a bush fire or slope constraint moves: a block that cannot use the complying development pathway shifts from the lower figure to the higher one before a brick is laid. | A$3,000 — A$15,000 |