Renovation vs Knockdown Rebuild Calculator
Not sure whether to renovate or knock down and rebuild? Enter your details below for an instant side-by-side cost comparison based on 2026 Sydney construction rates.
Your Property Details
180 m²
60% — 108 m² renovated
Renovation
Effective $1,569/m² of finished space
Result: 180 m² home (108 m² renovated)
Knockdown Rebuild
Effective $3,340/m² of brand-new space
Result: Brand new 180 m² home with full warranty
Our Assessment
At 47% of KDR cost, renovation is likely the better value for your situation. You save approximately $318,878 compared to a knockdown rebuild. Renovation works best when the existing structure is sound and you’re renovating less than 60–70% of the home.
Estimates are guides only, based on May 2026 Western Sydney construction rates (Rawlinsons-adjusted + Buildana live project data). Actual costs depend on site conditions, soil class, design complexity, and material selections.
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How the renovation vs KDR comparison works
The renovate-or-rebuild question is the most common decision Western Sydney owner-occupiers face on an existing block they already own. The wrong call costs $100k either way: spend half a new-build budget on a renovation that doesn’t solve the underlying floor-plan problem, or knock down a sound 1990s brick veneer that would have renovated cleanly for half the cost. The calculator above runs both scenarios in parallel against 2026 Western Sydney construction rates and surfaces the crossover point where one option starts to dominate the other.
How the model compares the two paths. Renovation cost is built from a per-m² rate scaled by scope intensity (cosmetic vs structural vs full strip-out) and any extension area, plus fixed costs for kitchen, bathrooms and services upgrades. KDR cost uses a per-m² new-build rate by finish tier (standard / premium / luxury) for the proposed new home size, plus demolition ($25k–$45k), site works and approvals. Both paths include holding/disruption costs (renovation: 3–6 months partial disruption; KDR: 8–14 months full off-site rental at typical Western Sydney rental rates).
The 60% rule. When projected renovation cost exceeds roughly 60–65% of the equivalent KDR cost, the rebuild almost always delivers better value — modern BCA-compliant structure, current BASIX energy efficiency, full builder warranty, and floor-plan flexibility you can’t get from working around an existing slab. The calculator highlights the crossover point on your inputs. Used with honest condition assessments, expect ±15% accuracy on either option against final delivered cost.
Frequently Asked Questions
Need a Precise Comparison?
This calculator gives estimates — Buildana gives answers. Book a free on-site assessment and we'll compare renovation vs KDR costs for your specific home.
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