Auckland · Adding floor area
The only place the official $/m² figure is genuinely useful — as the number your extension will not beat.
Auckland new dwellings consented at about $3,302 per square metre in May 2026. That is the efficient case: a clear site, one foundation, one scaffold, one roof, nobody living in it. An extension does all of that work in smaller quantities and then adds the hard parts — tying into a building that already exists. So treat the new-build rate as a lower bound and ask why any quote sits below it.
$3,302
Consented cost per square metre for new Auckland dwellings, May 2026: $381.6m of declared value across 115,565 m². This is the price of building new, used here as a lower-bound reference for adding floor area. It is not a renovation rate.
Stats NZ — Building consents issued — May 2026 (new dwellings, Auckland) · May 2026
Photography commissioned — plate reserved · July 2026
The method
Why the new-build rate is a floor and not an estimate.
This is the one page on this site that uses an official per-square-metre figure, and it uses it in one direction only. Everything that makes a new build efficient is absent from an extension, and everything that makes an extension hard is absent from a new build.
| Item | New house on a clear site | Extension to an existing house |
|---|---|---|
| Foundations | One pour, one setup, continuous. | Small pour, restricted access, and the existing foundation has to be assessed and sometimes underpinned. |
| Roof | One roof, one plane set, no interruptions. | A tie-in to an existing roof at a junction that must be weathertight for the life of the house. |
| Cladding | Continuous runs, one system, one scaffold. | New meets old. Matching, flashing and junction detailing on a wall that was never designed for it. |
| Demolition and disposal | Effectively none. | Cladding, lining, sometimes a whole wall, all of it removed and disposed of before anything is built. |
| Occupation | Empty site, full access, no protection. | A family is usually living there. Dust control, security, weather protection and staged access, every day. |
| Unknowns | Known ground, known structure. | What is behind the lining and under the floor is unknown until it is opened. This is the whole risk premium. |
| Scale efficiency | Every trade works in full-day runs. | Trades attend for part-days, and the setup cost is the same as it would be for a full day. |
This comparison is structural reasoning, not a measured cost differential — no New Zealand dataset publishes one. It is why the new-build rate reads as a floor.
This site — method note · July 2026
There is a second reason to be careful with the figure. It is a consented declared value, which is the applicant’s own estimate before construction, excluding land. It is the best per-square-metre number New Zealand publishes and it is still not a price anyone paid. The full disclosure is on the costs hub.
Stats NZ — Building consents issued — May 2026 (new dwellings, Auckland) · May 2026
The model
Ten trades on a 30 square metre addition.
The scope modelled is a single-storey extension of about 30 m² on a conventional site: new foundation, framing, roof tie-in, cladding, one bathroom-free fit-out, and making good where the new work meets the old. Design and consent input is included as architectural technician hours. Pay rates are published; hours are judgement.
| Trade | Median hourly pay | Assumed hours (judgement) | Wage cost |
|---|---|---|---|
| Carpenter | $31.25 | 520 | $16,250 |
| Construction manager | $59.13 | 90 | $5,322 |
| Roofer | $31.73 | 60 | $1,904 |
| Plasterer | $30.77 | 90 | $2,769 |
| Painter and decorator | $29.81 | 90 | $2,683 |
| Electrician | $41.35 | 50 | $2,068 |
| Plumber | $35.10 | 30 | $1,053 |
| Drainlayer | $37.98 | 30 | $1,139 |
| Glazier | $32.21 | 24 | $773 |
| Architectural technician | $39.90 | 70 | $2,793 |
Pay rates are the published median for each trade. The hours are this site’s judgement for the scope described above, not a measured figure — change the hours and the answer changes, which is exactly why no one can quote a renovation from a floor area.
Tertiary Education Commission — Tahatū Career Navigator · retrieved 2026-07-30
Photography commissioned — plate reserved · July 2026
From a wage to a price
The table above totals $36,754 of wages across 1054 labour hours for a single-storey extension of about 30 m². That is not what the work costs you. A charge-out rate also has to cover ACC levies, annual and sick leave, vehicles, tools, insurance, supervision, quoting time that never converts, office overhead and margin.
Across New Zealand trades a charge-out rate of 1.8× to 2.6× the wage is the ordinary range. That multiplier is judgement — no official source publishes it — so it is stated here rather than buried, and you can substitute your own. Applying it gives a modelled labour component of $66,157 – $95,559.
Materials, fittings, appliances, consent and inspection fees, scaffolding, skips, temporary works and the builder’s margin all sit on top of that. The labour component is usually the largest single line in a renovation, which is why a decade of labour cost rises has moved renovation prices far more than any material has.
Modelled on this site from Tahatū Career Navigator pay bands — labour only, not a quote · July 2026
Stats NZ — Building consents issued — May 2026 (new dwellings, Auckland) · May 2026
What to do
The sequence that keeps an extension honest.
- 01
Check the zone before you draw anything
Site coverage, height in relation to boundary, permeable surface, outdoor living space and any overlay. Start with what your zone allows.
- 02
Get the existing structure assessed
Foundations, framing and, if you are going up, whether the existing structure carries the load. This assessment is what turns a guess into a scope.
- 03
Design the junction first
The roof tie-in and the new-meets-old cladding detail decide both the price and the weathertightness risk. They are the design, not a detail.
- 04
Price it as a range against the floor
Start at $3,302/m² as a lower bound and work up with reasons. A number below the floor needs an explanation.
- 05
Confirm the consent and LBP position
Adding floor area is restricted building work. Get the consent path and the Licensed Building Practitioner arrangement in writing before work starts.
Questions people actually ask
Can I use the $3,302/m² new-build figure for my extension?
As a floor, yes. As a forecast, no. $3,302/m² is what Auckland new dwellings consented at in May 2026 — $381.6m of declared value across 115,565 m² of floor area. A new house is the efficient case: one foundation pour, one scaffold, one roof, no demolition, no existing building to tie into and nobody living in it. An extension does all of the same work in smaller quantities and adds the hard parts. So the honest reading is: an extension is very unlikely to cost less per square metre than a new build, and usually costs more. Anyone quoting below that figure is telling you something you should ask about.
Is it cheaper to extend or to move?
Extending buys you floor area on land you already own and keeps you in the street you chose. Moving buys you a known quantity. The costs are not comparable in kind: moving has fixed, knowable transaction costs, while extending has a genuinely unknown component until the ground and the existing structure are opened up. Price the move properly — commission, legal, moving, the price gap — because that is the side you can cost. Then hold your extension figure as a range with a contingency.
Do I need consent for an extension?
Adding floor area to a dwelling needs a building consent, and it is restricted building work — the primary structure and the external moisture-management system are both involved, so a Licensed Building Practitioner must carry out or supervise it. You may also need resource consent depending on your zone, site coverage, height in relation to boundary, and any overlay such as a Special Character Area. What your zone allows is here and the consent process is here. Both describe published rules; only Auckland Council can tell you what applies to your address.
What is the most expensive part of an extension?
Rarely the new part. It is the junction: the roof tie-in, the wall that becomes internal, the floor levels that do not match, the existing foundation that has to be assessed and sometimes underpinned, and the weathertightness detailing where new cladding meets old. That work is slow, it is skilled, and it cannot be scoped accurately until the existing building is opened up. It is also the reason an extension does not scale down neatly from new-build rates.
Is going up cheaper than going out?
Sometimes, and it depends almost entirely on what is already there. Going up avoids new foundations and does not consume site coverage or outdoor space, but it needs the existing structure and foundations to carry the load, adds a stair that consumes floor area on both levels, and usually means the house is unusable for longer. Going out is simpler to build and easier to stage, but consumes site and can run into coverage, height-in-relation-to-boundary and permeable-surface rules. It is a site-specific engineering answer, not a general one.
How long does an extension take?
The model here assumes 1054 labour hours across ten trades, which for a single-storey 30 m² addition typically runs four to six months on site, after design and consent. Consent processing and design sit in front of that. Those durations are judgement, not published data.
Consent and zoning information on this page describes the published rules and the Auckland Unitary Plan zoning map. It is not a determination about your property, and only Auckland Council can confirm what applies to your address. Much of the work described here is restricted building work under the Building Act 2004, which must be carried out or supervised by a Licensed Building Practitioner. This site does not yet name the trade partner who would do the work, and until it does it claims no licence, guarantee or membership.
One route from here
Send the site, not just the square metres.
The address suburb, the age and cladding of the house, roughly how much floor area you want and whether you are going up or out. That is enough for an honest reply about the band you are in and what has to be established before anyone can price it properly.