⚠️ The truth: Most homeowners spend 15–25% more than their builder’s quote. On a $600K build, that’s $90K–$150K in “extras” you didn’t budget for.
Your builder gives you a quote for $600,000. You think that’s what it’ll cost. It’s not. Here are the 15 costs most builders don’t mention — and how much to actually budget.
The 15 Hidden Costs
1. Site Costs ($10,000 – $60,000+)
Your builder’s quote usually includes a “site costs allowance” — typically $15K–$25K. If your block has reactive clay, slope, rock, or poor drainage, the actual site costs can be 2-3x this allowance. Always get a soil test before signing a contract.
2. Landscaping ($10,000 – $80,000+)
Your builder delivers a house surrounded by dirt. Everything outside — turf, plants, paths, retaining walls, irrigation, outdoor lighting — is extra. Budget $15K–$30K minimum for a basic front and back yard.
3. Fencing ($5,000 – $20,000)
Most contracts include one side of boundary fencing or none at all. A full Colorbond fence for a standard 500sqm block costs $8K–$15K. Timber costs more.
4. Driveway and Crossover ($3,000 – $15,000)
Your builder may include the driveway from garage to boundary, but the crossover (the part from boundary to road) is usually excluded. Council may also require specific crossover specifications.
5. Blinds and Curtains ($3,000 – $15,000)
Almost never included in a build quote. A 4-bedroom home with roller blinds starts at $3K. Plantation shutters or motorised blinds can reach $15K+.
6. Air Conditioning ($5,000 – $20,000)
Some builders include ducted heating but not cooling. Others include split systems to bedrooms only. Full ducted reverse-cycle for a 250sqm home: $10K–$18K.
7. Connection Fees ($5,000 – $15,000)
Connecting your new home to water, gas, electricity, and NBN. Each has its own fees. Sewer connection alone can be $3K–$8K depending on distance to main.
8. Council Permits ($5,000 – $15,000)
Planning permit (if required): $1K–$5K. Building permit: $2K–$5K. Inspection fees. Bond fees. Some councils require a “damage deposit” for construction vehicles.
See your real build cost — including the extras
Our calculator accounts for site costs, connections, and the hidden extras most estimates miss.
9. Architect/Designer Fees ($15,000 – $60,000)
If you’re not using a volume builder’s standard design, expect to pay 3–8% of the build cost for architectural design. A $600K build: $18K–$48K in design fees.
10. Soil Test and Survey ($2,000 – $5,000)
Required before building. Soil test: $500–$1,500. Feature and level survey: $500–$1,500. Engineering assessment: $500–$2,000.
11. Upgraded Inclusions ($10,000 – $50,000+)
Your builder’s “standard inclusions” might include laminate benchtops, basic tapware, and builder-grade tiles. Upgrading to stone benchtops, quality tapware, and feature tiles adds up fast. The display home you loved? That’s the upgraded version.
12. Window Furnishings ($1,000 – $5,000)
Flyscreens, security screens, and window tinting. Often excluded from the build quote.
13. Letterbox, Clothesline, TV Antenna ($500 – $2,000)
Small items that add up. Your builder might include a letterbox but not a clothesline or TV antenna point.
14. Temporary Accommodation ($15,000 – $40,000)
If you’re doing a knockdown rebuild, you need somewhere to live for 10–22 months. At $400/week rent, that’s $17K–$36K.
15. Interest During Construction ($10,000 – $25,000)
If you have a construction loan, you’re paying interest on the progressive drawdowns during the 12–18 month build. This can add $10K–$25K that people don’t factor into their “total build cost.”
Total Hidden Costs: What to Actually Budget
| Category | Minimum | Typical | Maximum |
|---|---|---|---|
| Site costs (above allowance) | $0 | $15,000 | $40,000+ |
| Landscaping | $10,000 | $25,000 | $80,000+ |
| Fencing | $5,000 | $10,000 | $20,000 |
| Driveway/crossover | $3,000 | $6,000 | $15,000 |
| Blinds | $3,000 | $6,000 | $15,000 |
| A/C (if not included) | $5,000 | $12,000 | $20,000 |
| Connections | $5,000 | $8,000 | $15,000 |
| Permits | $3,000 | $7,000 | $15,000 |
| Upgraded inclusions | $0 | $15,000 | $50,000+ |
| Other (letterbox, screens, etc.) | $1,000 | $3,000 | $5,000 |
| Total hidden costs | $35,000 | $107,000 | $275,000+ |
Our recommendation: Add 20–25% to your builder’s quote for the true move-in-ready cost. On a $600K build, budget $720K–$750K total.
Upgraded inclusions add $10K–$50K+
The display home finishes aren't the standard ones
How to Protect Yourself
- Get a fixed-price contract with a detailed inclusions list
- Get a soil test before signing — don’t rely on the builder’s site cost “allowance”
- Ask for the upgrade price list upfront — know what the display home extras cost
- Budget separately for landscaping, fencing, blinds, and connections
- Include a 10% contingency beyond the hidden costs
- Read the contract exclusions page — this is where the hidden costs live
Costs based on Q1 2026 Australian market data.
Related Guides
- Cost to Build in Melbourne — Full cost breakdown
- Cost to Build in Sydney — Sydney costs
- Build vs Buy — Compare the true costs
- Construction Loan vs Home Loan — Finance explained
