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Granny Flats & Secondary Dwellings Cost Calculator

Detached secondary dwellings, modular prefabricated granny flats, studio conversions, and dual-occupancy builds.

Benchmark Installed Rate (Fair Work CW3)
$2200–$3800/m²
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45m²
30m²60m²

Standard statutory cap under NSW SEPP & VIC Small Second Dwelling is 60m² internal floor area.

600m²
350m²1200m²

Qualifies for standard Complying Development (CDC) or fast-track building permit pathways.

Turnkey Turnout EstimateCW3 Award + Major Works Insurance
$98,850~$2197/m²
Build Program:~56 Working Days
Statutory Plan:NSW 60m² Fast-Track

Itemised Cost Breakdown

Includes footings/piers, services connections (sewer/power/water), internal fit-out, and private certifier fees.

AUD

45m² @ $2000/m²

$90,00091%

Council infrastructure levy

$5,2505%

Complying Development approval

$2,7503%

Council processing

$8501%
Total Estimated Cost$98,850 AUD

Fast-Track CDC Eligible

NSW minimum lot size (450m²) is met.

  • ✅ Fast-Track Complying Development path available
  • ✅ Faster than standard DA (2-4 weeks vs. 8-12 weeks)
  • ✅ Lower cost ($1,500-$3,000 vs. $3,000-$8,000)
  • Section 7.11/7.12 developer contribution still applies
Statutory Planning Fast-Track Summary

In Victoria, secondary dwellings under 60m² no longer require a planning permit on lots ≥300m² under the Small Second Dwellings reform. In NSW, comply with 3.0m rear and 0.9m side boundary setbacks under the Housing SEPP to bypass council DA delays.

Review state secondary dwelling planning guidelines

Material Price Brackets

Modular Flatpack / Prefab (1 Bed, 30-40 sqm)
$1800–$2400/m²

Factory-built steel chassis modular pods. Fast assembly on pier foundations.

Expected lifespan: 30+ yrs years

Standard Turnkey Build (2 Bed, 60 sqm)
$2400–$3200/m²

Complete slab-on-ground brick veneer or clad construction including bathroom/kitchen.

Expected lifespan: 50+ yrs years

Architectural Custom Design (60 sqm)
$3200–$4500/m²

High-end timber cladding, raked ceilings, double glazing, and premium finishes.

Expected lifespan: 60+ yrs years

Want Council Exemption Rules for Your Property?

Select your local government area to check planning regulations, boundary setback thresholds, and statutory council approval requirements.

Browse Council LGAs