Ground-floor pushes out the footprint. Second-storey adds up. Knock-down / rebuild defers to a quote.
Knock-down & rebuilds need a site visit and detailed scoping, they're too variable for a calculator. We'll send a fixed-price quote within 5 business days. Hit "Show my estimate" below to start that process.
2
Roughly what floor area are you adding?
A small bedroom is ~12 m². A new master + ensuite is ~25-35 m². A whole second storey is typically 60-100 m².
35m²
≈ 1 bedroom + ensuite
15 m²50 m²85 m²120 m²
3
What finish level?
Drives the per-m² rate. Most Sydney homeowners land in mid-tier.
4
Structural complexity
Tells us how much engineering, propping and groundworks are likely needed.
Heads up, underpinning risk: Second-storey additions on older Sydney homes (especially pre-1970s) commonly need underpinning at $1,500-$3,500 per linear metre. We always check with a structural engineer before we quote. Range widened to ±18% to account for it.
5
Wet areas inside the new space
Each adds a fixed range based on tier. Skip if it's just bedrooms / living.
6
Site factors
Tick anything that applies. These each push the build cost up.
Heritage / conservation overlays in Sydney typically add 6-15% to total cost (matching materials, council conditions, longer DA). We've widened the range to ±18% to reflect that variability.
7
Sydney postcode
Eastern Suburbs / Lower North Shore / Northern Beaches sit ~15% above the Sydney baseline; Inner West heritage pockets ~10% above.
Sydney baseline, enter postcode to refine
How this estimator works: Per-m² rates are triangulated from RLB & Altus 2026 cost guides, Master Builders / HIA NSW data, the ABS PPI, and Piper Moss's actual completed projects. Suburb premiums reflect 2025-26 wage and material differentials. Numbers are indicative for budgeting only, a fixed-price quote requires a site visit, structural pre-check and detailed scoping.
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