AU cost per m² (approx, metro, 2024–25):
Budget: $1,500–$1,900/m² · Standard: $2,000–$2,800/m² · Mid-range: $2,800–$3,800/m² · Prestige: $3,800–$6,000+/m²
Double-storey adds ~10–15% per m². Extensions typically cost 20–30% more per m² than new builds due to tie-in complexity.
Not included: Land, site costs (slab, retaining, drainage), council fees, landscaping, driveway, fencing.

Renovation costs are notoriously variable. Key factors: structural changes (moving walls = expensive), quality of fixtures and finishes, whether existing plumbing/electrical needs relocating, and builder availability in your area.
Budget renovations use standard fixtures and cosmetic changes only. Prestige renovations involve custom joinery, imported tiles, and high-spec appliances.
Always get 3 quotes and add a 15–20% contingency to any renovation budget.

AU (platform frame): 90×45mm or 70×45mm MGP10/12 pine at 450mm or 600mm centres. Noggings at mid-height for stability.
US (stick frame): 2×4 or 2×6 lumber at 16" or 24" on-centre. Fire blocking required at mid-height per IRC.
Double top plate is standard in both AU and US. Corner studs require 3 studs (AU) or king/jack configuration (US).
Add 10–15% to stud count for waste, cutting and corners.

AU (plasterboard): Standard 1200×2400mm, 10mm walls, 13mm ceilings. Also 1200×3000mm for 2.7m ceilings (fewer joints). Fire-rated, moisture-resistant and acoustic sheets available.
US (drywall): Standard 4×8ft (most common), 4×12ft reduces joints. ½" (12.7mm) walls, ⅝" (15.9mm) fire-rated and ceilings.
For ceilings, standing seam direction matters — always run sheets perpendicular to joists.

This is one of the most confusing things in construction:
AU R-value is in m²·K/W (SI units). R2.5 in Australia = about R14 in the US.
US R-value is in ft²·°F·hr/BTU (imperial). R-13 in the US = about R2.3 in Australia.
Conversion: US R-value ÷ 5.678 = AU R-value · AU R-value × 5.678 = US R-value
Always check which scale a product is rated in before specifying.

AU standard brick: ~47–50 bricks/m² (single skin, 10mm joints)
AU besser block: ~12.5 blocks/m² (390×190mm face, 10mm joints)
US modular brick: ~35 bricks/m² (~3.26 bricks/sqft)
Always order 5–10% extra for cuts and wastage. Verify bond pattern (stretcher, Flemish, stack) with your mason as this affects quantity.

Coverage varies by product and application thickness. Typical rates:
Sand-cement render (15mm): ~25–30 kg/m² · Acrylic base coat (5mm): ~8–10 kg/m²
Texture/finish coat (3mm): ~3–5 kg/m² · Floor screed (50mm): ~70–80 kg/m²
Always check manufacturer's TDS (Technical Data Sheet) for exact coverage — products vary significantly.

AU on-costs: Superannuation (11% SGC) + Workers Compensation insurance (2–8% depending on trade) + Long Service Leave levy (varies by state) + annual leave loading. Total: typically 20–25% on top of base rate.
US on-costs: FICA (Social Security 6.2% + Medicare 1.45%) + Federal/State unemployment (FUTA/SUTA ~3%) + Workers Comp (varies by state/trade, 2–15%). Total: typically 18–30%.

AU (Development Approval + Construction Certificate): DA fee (based on construction value), Construction Certificate fee, Inspection fees, Long Service Levy (0.35% of contract value in NSW), Section 7.11 contributions (for new builds). Total typically 1.5–3% of construction value.
US (Building Permit): Base permit fee + plan review fee. Ranges from $500 (simple reno) to $5,000+ (new build). California typically 2–5% of project value.
Always verify with your local council / building department — fees vary significantly.