How Much Does a House Extension Cost in NZ? (2026)
Typical cost in NZ
$3,500/m²
A house extension in New Zealand typically costs around $3,500/m² per m², ranging from $2,500/m² for a budget job to $5,500/m²+ at the premium end. The figures below break down what each level gets you, what drives the price, and how it varies by region.
House Extension cost by level
Budget
$2,500/m² – $3,000/m²
Simple single-room ground-floor addition on a straightforward, level site.
Mid-range
$3,000/m² – $4,000/m²
Standard living or bedroom extension with new services and matching finishes.
Premium
$4,000/m² – $5,500/m²
Complex or sloping site, structural work, high-end finishes.
What changes the price
| Factor | Impact | Why |
|---|---|---|
| Extension size | inverse | Fixed consent/design costs make small extensions dearer per m². |
| Connecting to the existing house | +$5k–$20k | Matching cladding/roofline, structural tie-ins and reworking existing rooms. |
| Services | +$3k–$15k | New plumbing, drainage and electrical runs to the addition. |
| Consent & design | +$5k–$10k | Building consent ($2k–$5k) plus drawings and any engineering. |
House Extension cost by region
Indicative per-m² rates based on the typical figure, adjusted for regional labour and material differences.
Auckland
$4,020/m²
Wellington
$3,710/m²
Christchurch
$3,430/m²
Regional NZ
$3,150/m²
What's usually included — and what isn't
Usually included
- Foundation & framing for the new space
- Cladding & roof to match
- Interior lining & finishes
- Connection to the existing structure
Usually extra
- Reworking unaffected existing rooms
- Major structural changes to the original house
- Landscaping around the addition
- Council consent fees
Typical timeline
8–20 weeks
Building consent
Usually required
Most extensions need a building consent; check whether your site or zone also triggers resource consent.
Read the full consent answerA house extension is one of the biggest cheques you'll write.
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Getting quotes without getting burned
Red flags in a quote
- No allowance shown for tying the new structure into the old one
- A deposit far above the cost of materials being ordered first
- No written, fixed-scope contract
Questions to ask
- How will the new section connect structurally to the existing house?
- Is the consent included, and who lodges it?
- What happens to the price if hidden issues are found in the existing wall?
Find registered trades near you
Ready to get quotes? Browse registered house extension trades by city — then run a background check on each one before you sign.
Frequently asked questions
- How much does a house extension cost per square metre in NZ?
- Most ground-floor extensions run $2,500–$4,500/m² in 2026. A typical 30m² room addition therefore costs roughly $90,000–$135,000 including connection and finishes, plus consent and design.
- Why do small extensions cost more per square metre?
- Fixed costs — consent, design, getting trades on site — don't shrink with the project. Spread over fewer square metres, the per-m² rate rises.
Related cost guides
Sources: Superior Renovations house-extension guide 2025/26; Builders Near Me NZ home-extension cost guide 2026. Figures are 2026 estimates for guidance only and exclude GST unless stated — always get written quotes for your specific project. Last updated 2026-05.