Garage Conversion Cost NZ: Bedroom, Double Garage and Granny Flat Prices
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Garage Conversion Cost NZ: Bedrooms, Bathrooms and Double Garages
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How much will a garage conversion cost?
Answer a few questions and we’ll email you an Auckland price range.
Quick answer: A garage conversion in Auckland starts from around $40,000 for a dry room such as a bedroom, office or gym. Adding a bathroom takes it to $80,000–$110,000, a self-contained single-garage unit runs $110,000–$145,000, and a double garage turned into a two-bedroom unit lands at $160,000–$220,000, build cost only.
You’re staring at the garage. The car’s parked on the drive most weeks anyway. What if that space became a teenager’s bedroom, a home office, a rental income stream, or somewhere for your mum to live closer without moving in?
The first question is always the same: what’s it actually going to cost? You’ve probably already pulled up a few ranges online, and they run from about $30,000 to well past $200,000. Useful as a wall poster. Useless for planning. Once you’ve got a budget in mind, see how we turn an Auckland garage into a consented, habitable room, from the first drawing to the final inspection.
What you need is a number that fits your garage. Your section. Your conversion type.
That’s what this calculator gives you.
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A short set of questions about your project, then where to send the result. Free, and no obligation.
How Much Does a Garage Conversion Cost in NZ?
The type of room you’re creating sets the price far more than the size of the garage does. These are the bands Superior Renovations publishes for Auckland: the starting point on our renovation FAQ, and the project bands in our garage to granny flat cost and consent guide.
| What you’re creating | Typical floor area | Build cost (Auckland) |
|---|---|---|
| Dry room in a single garage: bedroom, office, gym or studio | 18–22m² | From around $40,000, typically $40,000–$60,000 |
| Habitable room, no kitchen or bathroom | ~30m² | $55,000–$80,000 |
| Habitable room with a bathroom | ~30m² | $80,000–$110,000 |
| Self-contained unit with kitchen and bathroom | ~30m² | $110,000–$145,000 |
| Double garage to a two-bedroom unit | ~50–60m² | $160,000–$220,000 |
| New detached granny flat instead of converting | Up to 70m² | $180,000–$260,000 |
Those are build costs, and they leave three things out. Design and consent typically add $10,000–$20,000. A self-contained unit with its own kitchen can trigger Auckland Council Development Contributions of $5,000–$20,000 depending on the zone. And foundation remediation or a drainage pump system sits outside the bands too, which is why we tell people to hold a 10–15% contingency on top of any quoted figure.
Notice the two-bedroom row needs 50–60m². A standard double garage is 36–40m², so measure yours before you plan for two bedrooms.
Why a Calculator Beats a Generic “Per m²” Estimate
On our own published bands, an Auckland garage conversion runs from around $40,000 for a bedroom to $220,000 for a two-bedroom unit. That’s accurate. It’s also useless for budget planning.
The range is that wide because “garage conversion” covers wildly different projects. Converting a single garage into a teenager’s bedroom on a flat section in Albany sits at the bottom. Turning a double garage into a self-contained granny flat with kitchen, bathroom, and separate entry on a leaky-era home in Glen Eden sits near the top. Both are “garage conversions in Auckland.” Both sit inside that spread. They cost vastly different amounts.
The headline range alone doesn’t tell you which one you are.
That’s where the calculator earns its keep. Instead of giving you a number that covers everyone, it asks the specific questions that move your number, type of room, size of garage, whether you need plumbing, the condition of what’s already there, and narrows the range to the kind of project you’re actually planning.
It takes a few minutes, and what it gives you isn’t a quote. More on that below.
What Goes Into the Estimate
The calculator works through the same variables we look at when we price a real project. Each one is a genuine cost driver, and below is roughly what each does to the number.
Type of conversion. This is the single biggest driver. A dry-room conversion (bedroom, study, gym) starts from around $40,000. Add a bathroom and you’re at $80,000–$110,000. A self-contained unit with kitchen, bathroom and separate entry runs $110,000–$145,000 in a single garage, and $160,000–$220,000 as a two-bedroom unit. The jump isn’t linear: wet areas need plumbing, drainage connections, waterproofing, ventilation and higher-spec fixtures.
Size of the garage. Single garages typically run 18–22m². Double garages 36–40m². A double conversion costs more in absolute terms but the per-m² rate often comes down because fixed costs (consent fees, design, structural assessment) spread across more floor area.
Foundation and floor condition. Most garage slabs were never designed for habitable use: often no damp-proof membrane and no insulation underneath. Bringing the floor up to habitable standard means either insulating over the existing slab (you lose ceiling height) or breaking out and re-pouring, which we’d budget at roughly $8,000–$15,000 as an indicative planning figure. A slab that sits below the surrounding ground is harder again, because getting drainage to work around it gets complicated quickly.
Insulation and weathertightness. Turning a garage into habitable space brings the H1 energy-efficiency clause into play, so walls, ceiling and floor all have to hit current R-values. The current documents (H1/AS1 and H1/VM1, 6th edition) took effect on 27 November 2025, and the previous 2022 editions stay valid only for consents lodged up to 26 November 2026 — worth asking which edition your design is being drawn to. Most garages were never lined or insulated in the first place, so plan on insulating the lot. Our guide to insulating an NZ home covers the products and where each one goes.
Plumbing and electrical. Running new water, waste and drainage to a detached garage costs more than to an attached one. On a self-contained unit, the longer runs and separate connections can add $10,000–$25,000 over the same conversion on an attached garage, and a low-lying site that can’t get fall to the sewer may need a pump system as well, at $4,000–$8,000 plus ongoing maintenance. Electrical needs to be brought up to current Standards and usually means a new sub-board.
Finish level. Standard GIB and vinyl, or feature timber lining and engineered flooring? On a 30m² self-contained conversion, interior finishes (flooring, painting, ceiling, joinery) typically run $12,000–$18,000 at a standard spec. Feature linings and premium flooring push that line up fast.
💡 Quick tip: The cheapest conversion isn’t always the smartest one. A $60K dry-room conversion can become a $120K rework two years later when you realise you needed a bathroom. Plan for what the space will actually do, not just what you can afford this year.
See Your Personalised Number
Room type, size, plumbing and condition: the four inputs that move the number most.
What the Calculator Gives You, and What It Can’t
The calculator asks a short set of questions about your project, then where to send your result. Treat what comes back as a planning range, not a price.
It’s not a quote. Quotes need site visits, drawings, and detailed scope. The estimate is the layer before that: the number that tells you whether your project sits in a budget you can work with, or whether you need to rescope before going further.
Check what any number leaves out. The bands on this page are build costs. Design and consent fees, Development Contributions on a self-contained unit, resource consent if your plans breach a zone rule, and anything hiding under the slab or behind the existing lining all sit outside them. We’d rather flag the limits than pretend they don’t exist.
If the number looks workable, the next step is usually a feasibility consultation, where we walk through your specific garage, what you’re trying to achieve, and what’s realistic on your section. The consent drawings come from Sonder Architecture, our architectural division, so the people drawing your garage work alongside the team that builds it. That conversation comes after you’ve seen the estimate, not before.
Single, Double or Detached: What Your Garage Type Changes
Two things about your garage set the shape of the whole project before anyone talks about finishes: how big it is, and whether it is attached to the house.
Single Garage Conversions (roughly 18–22m²)
A single garage gives you one good room. A bedroom, a home office, a gym, a studio. It is the cheapest conversion available and it sits at the bottom of the $40,000–$60,000 dry-room band, but the per-square-metre rate is the highest of any conversion type, because the consent, design and structural assessment cost the same whether you are converting 20m² or 40m².
If you want a bathroom in a single garage, be realistic about what is left. Take out 3–4m² for a compact bathroom and the habitable room that remains is small. That is usually the point at which people either accept a dry room or start looking at the double.
Double Garage Conversions (roughly 36–40m²)
This is the footprint that makes a genuinely self-contained unit work: open-plan living, a bedroom, a bathroom and a kitchenette without any of it feeling like a corridor. It also spreads the fixed costs across twice the floor area, so the per-m² rate drops even though the total goes up. Two bedrooms is the stretch: our published band for a two-bedroom unit is $160,000–$220,000 at 50–60m², which is more floor area than a standard double, so a disciplined layout and smaller rooms are the price of fitting both in.
Attached vs Detached: The Services Question
An attached garage is almost always the cheaper conversion, and the reason is plumbing rather than structure. Water, waste and drainage are already a few metres away, and the wall between garage and house is often already close to a habitable build-up.
A detached garage at the back of the section is a different job. Water, waste and drainage have to be trenched out to it, and on a self-contained unit those longer runs and separate connections can add $10,000–$25,000 over the same conversion on an attached garage, before anything happens inside the building. Power usually means a new sub-board and a run out to the structure. Detached conversions also tend to be the ones that hit boundary, height-to-boundary and impervious-area rules, because they sit near the edge of the section.
| Garage | Typical footprint | What it realistically becomes | Band |
|---|---|---|---|
| Single, attached | 18–22m² | One good room: bedroom, office, gym | $40,000–$60,000 |
| Single, with bathroom | 18–22m² | Bedroom plus compact bathroom, tight | $80,000–$110,000 |
| Double, attached | 36–40m² | Self-contained unit with room to move; two bedrooms only in a larger garage | $110,000–$220,000 |
| Detached, any size | — | Add services trenching and boundary-rule risk | +$10,000–$25,000 on services for a self-contained unit |
Converting a Garage Into a Bedroom
This is the most common brief we get, and it is the cheapest useful thing a garage can become. There is no plumbing, no drainage, no waterproofing, so the whole wet-area cost jump never happens.
What it still needs, and what people underestimate: the slab has to come up to habitable standard, which means either insulating over it and losing ceiling height, or breaking it out and re-pouring (allow roughly $8,000–$15,000 as an indicative figure). The walls, ceiling and floor all have to meet current H1 R-values. The garage door opening usually becomes a window or a wall, and that changes both the structure above it and the look of the street frontage. Ventilation and natural light have to satisfy the Building Code for a habitable room, which a garage was never designed to do.
💡 Quick tip: Check your ceiling height before you fall in love with the idea. Insulating over an existing slab eats 100mm or more, and a garage that started low can end up below the height a habitable room needs. Measure first, design second.
Whether the finished room can be rented, and whether it counts as a separate dwelling for rates and consent purposes, is a question for Auckland Council or a Licensed Building Practitioner rather than a calculator. If you are weighing the conversion against other ways of adding a room, our guides to converting a garage into a granny flat, container homes versus regular granny flats, and the cost of building a new garage cover the alternatives. If losing the garage is the sticking point, our garage build cost guide prices putting a replacement elsewhere on the section.
Converting a Garage Into a Kitchen, Studio, Gym or Living Area
Bedrooms get the most enquiries, but plenty of people want something else from the space. One rule holds across all of them: dry rooms are cheap, wet rooms are not, and a kitchen changes what the building is.
Garage to Home Office, Studio or Gym
Price these like a bedroom. There’s no plumbing, so they sit in the same dry-room band that starts from around $40,000, and the same slab, insulation, light and ventilation work applies once you intend to use the space as a habitable room. A gym is the one to think twice about. Heavy plates on a slab that’s been insulated over need a floor build-up that can take the load, so tell the designer what you’ll be lifting before the floor is specified.
Not every gym or workshop has to become a habitable room. Our granny flat guide treats a space with no plumbing that nobody sleeps or works in full-time as non-habitable, which is a smaller and cheaper job. Whether yours qualifies is a question for Auckland Council or a Licensed Building Practitioner, not a calculator.
Converting a Garage Into a Kitchen
Adding a kitchen is where the project changes category. A garage with its own kitchen and bathroom is a self-contained unit, which runs $110,000–$145,000 in a single garage on our published bands, and in Auckland a second self-contained unit commonly brings resource consent and Development Contributions into play alongside the building consent. If what you actually want is a second cooking space for the main house, such as a scullery or an entertaining kitchen off the living area, say so at the design stage, because how the space is classified changes the consent path. Check your zone with Auckland Council or ask us before you draw it.
Garage to Living Space: Extending the House Into It
An internal or attached garage that opens straight into the house is the easiest conversion to make feel like part of the home. Widen the internal doorway and the garage becomes a family room, rumpus or second lounge, with services close by and no separate entry to build. The wall you open up is the structural question. If it’s load-bearing, get an engineer and an LBP involved before anyone picks up a saw, and expect the beam to be part of the consented work. Attached conversions can also need a fire-rated wall between the new room and the rest of the house, depending on the design.
Half a Garage: Converting One Bay of a Double
Keeping one car bay and converting the other is a popular compromise where the section has nowhere else to park. Just don’t expect half the garage to cost half as much. The design, consent and structural assessment cost much the same whatever the floor area, and you’re adding a new wall between the room and the remaining car bay, built to habitable-room standard on the room side. Per square metre, a half conversion is one of the more expensive ways to add a room, so price the full double before you rule it out.
The Three Variables That Move Your Number the Most
If you’ve used the calculator and want to understand what drove your result, these three factors do most of the heavy lifting.
1. Whether you’re adding plumbing. The single biggest jump in cost is the leap from a dry room to a wet one. On our published bands, adding a bathroom takes a project that starts from around $40,000 to $80,000–$110,000, and adding a kitchen as well takes a single-garage unit to $110,000–$145,000. If the goal is just usable floor space, a dry-room conversion gives you the best return per dollar. If you’re going self-contained, expect the budget to roughly double or more.
2. Condition of the existing structure. Garages weren’t built to habitable standard. A garage with a sound slab, intact roof, good wall framing and services nearby converts faster and cheaper. A tired garage with rotting bottom plates, a cracked slab or old fibre-cement cladding can soak up a big share of the budget before the conversion proper even starts, and anything that might contain asbestos needs testing before anyone cuts into it. Our guide to asbestos testing and removal in an Auckland renovation explains who tests, who pays and what happens next. Get a builder to assess the structure before you commit to a budget.
3. Labour, and how it’s priced. Qualified trades in Auckland charge $120–$150 an hour, the rate Superior Renovations publishes on its FAQ, and a conversion runs a builder, electrician, plumber, gib stopper and often a tiler in sequence. A fixed-price quote can look higher than a charge-up estimate because the builder is carrying the risk of whatever turns up behind the lining. On a charge-up job, that risk sits with you.
Where the money goes on a self-contained conversion. Our granny flat guide breaks a $130,000, 30m² self-contained build down like this: bathroom $22,000–$28,000, kitchenette with appliances $18,000–$28,000, slab works, linings, insulation and weather membrane $25,000–$35,000, plumbing and electrical $15,000–$22,000, glazing and joinery to replace the garage door $12,000–$18,000, and interior finishes $12,000–$18,000.
Knowing which of these three is the biggest factor on your garage tells you where to focus when you’re trying to bring the number down, or where to brace yourself if it has to stay where it is.
Convert the Garage, or Demolish and Build New?
This question matters more in 2026 than it did a year ago.
In January 2026, the Schedule 1A granny flats exemption came into force. According to MBIE’s Building Performance guidance, a small standalone dwelling of up to 70m² can be built without a building consent if it has a simple design and meets the Building Code, the homeowner notifies council before building starts and once it’s complete, the work is carried out or supervised by licensed building professionals, and every exemption condition is met. That’s a structural shift in the economics of adding a second dwelling to your property.
Here’s the awkward bit: the exemption applies to building new, not to converting existing structures. A garage conversion still triggers building consent because it changes the use of an existing building, involves structural alterations, and almost always involves plumbing and electrical work.
Which means homeowners now have a genuine choice:
Convert the existing garage. Cheaper if the garage is in good condition. Faster start. Keeps the existing footprint. Consent required. From around $40,000 to $220,000 depending on scope.
Demolish the garage and build a new exempt dwelling of up to 70m². Higher upfront cost: our published band is $180,000–$260,000 for the build. But no building consent and no consent processing wait, more floor area, and standalone status. You still apply for a project information memorandum (PIM), notify council before and after, and pay any development contributions, and resource consent is a separate question that depends on your zone. The numbers can work out closer than they look once you factor in the consent timeline avoided.
The break-even point depends heavily on the condition of the existing garage. If it’s structurally sound with good services nearby, convert. If it’s rotten, undersized, or full of asbestos, the new-build pathway can be the cleaner answer.
The calculator gives you the conversion estimate. If you want to weigh that against a new-build SSAD option, that’s worth a feasibility conversation before you commit to either path.
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➡ Book your free in-home consultation with Superior Renovations
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Frequently Asked Questions
Is the garage conversion cost calculator free?
Yes. There's no charge and no obligation. Superior Renovations built it so Auckland homeowners can get a realistic starting range for a garage conversion before they talk to anyone. It asks a short set of questions about your project and where to send the result, and what it gives you is a planning figure rather than a quote.
How accurate is the estimate?
Accurate enough for budget planning and feasibility, not for signing a contract. It works from the variables that genuinely move the price, such as the type of room, the garage size, plumbing and the condition of the building, but it cannot see your slab, your drainage fall or what's behind the existing lining. Final pricing needs a site visit, drawings and a detailed scope.
How much does a garage conversion cost in Auckland?
On Superior Renovations' published bands, a dry room such as a bedroom, office or gym starts from around $40,000. A habitable room with a bathroom runs $80,000–$110,000. A self-contained single-garage unit with kitchen and bathroom runs $110,000–$145,000, and a double garage converted to a two-bedroom unit of 50–60 square metres runs $160,000–$220,000. Those are build costs; design and consent typically add $10,000–$20,000.
Does a garage conversion require building consent in Auckland?
Yes, almost every garage conversion needs building consent because it changes the use of the structure from non-habitable to habitable and usually involves structural, plumbing and electrical work. Budget $10,000–$20,000 for design and consent together, and check Auckland Council's building control fees for the council's share. Resource consent is separate: it applies if the design breaches a zone rule such as a boundary or height-to-boundary standard, and is commonly needed when the garage becomes a second self-contained unit.
Can I use the new Schedule 1A granny flats exemption for a garage conversion?
No. According to MBIE's granny flats exemption guidance, the Schedule 1A exemption covers small standalone dwellings of up to 70 square metres, not the conversion of an existing structure. If your garage is in poor condition, demolishing it and building a new exempt dwelling can be the cleaner path. You skip building consent, but you still notify council before and after the build, apply for a PIM, and use licensed building professionals.
What's the difference between a garage conversion and a granny flat?
A garage conversion means turning an existing garage into habitable space, which can be a single room, a bedroom-plus-bathroom, or a fully self-contained unit. A granny flat is the self-contained unit at the top end of that spectrum, with its own kitchen, bathroom, and separate entry. Not every garage conversion is a granny flat. Every granny flat conversion is a garage conversion.
How much does a double garage conversion cost?
It depends on what goes in it. A standard double garage is 36–40 square metres, enough for a one-bedroom self-contained unit with a real bedroom, bathroom and kitchen. Superior Renovations' published band for a two-bedroom self-contained unit of 50–60 square metres is $160,000–$220,000, build cost only, so two bedrooms usually needs a larger-than-standard garage. A double converted to dry rooms only, such as a bedroom and a rumpus, costs far less because there's no wet-area work.
Does the estimate include GST and consent fees?
Treat the bands on this page as build cost only. Design and consent fees (typically $10,000–$20,000), Auckland Council Development Contributions on a self-contained unit ($5,000–$20,000 depending on the zone), foundation remediation and drainage pump systems are extra. When you compare a calculator figure with a builder's quote, check whether each one includes GST, because a 15% difference is easy to mistake for a cheaper builder.
How long does a garage conversion take?
Superior Renovations puts a typical Auckland garage conversion at 4–12 weeks on site, driven mostly by whether you're adding a bathroom and a kitchen. Design and building consent come before that and take time of their own, so the whole project from first drawing to finished room runs longer than the build itself. A dry-room bedroom conversion sits at the short end of that range.
How much does it cost to convert a garage into a kitchen or studio?
A studio, home office or gym has no plumbing, so it prices like a bedroom, from around $40,000. A kitchen changes the category: a garage with its own kitchen and bathroom is a self-contained unit, which runs $110,000–$145,000 in a single garage on Superior Renovations' published bands, and in Auckland it commonly brings resource consent and Development Contributions into play. Confirm your zone with Auckland Council before you design one.
How much does it cost to convert a garage into a bedroom in NZ?
A dry-room conversion, which is what a bedroom is, sits at the bottom of the range, from around $40,000 and typically $40,000-$60,000 for a single garage in Auckland. There is no plumbing, drainage or waterproofing, so you avoid the biggest cost jump in the whole project. The work that remains is bringing the slab up to habitable standard (insulating over it, or breaking out and re-pouring at roughly $8,000-$15,000 as an indicative figure), meeting current H1 R-values in the walls, ceiling and floor, closing in or reworking the garage door opening, and satisfying the Building Code on ventilation and natural light.
Is it cheaper to convert an attached or a detached garage?
Attached, almost always, and the reason is services rather than structure. Water, waste and drainage are already metres away on an attached garage. On a self-contained unit, the longer runs and separate connections to a detached garage can add $10,000-$25,000 over an equivalent attached conversion, a low-lying site may need a pump system at $4,000-$8,000, and power usually means a new sub-board plus a run out to the structure. Detached garages are also the ones that most often run into boundary, height-to-boundary and impervious-area rules, because they sit near the edge of the section.
Please note: Cost factors vary project to project, and the calculator’s accuracy depends on the inputs you provide. The estimate is a planning tool, not a quote. Rates and material costs shift with the market, and final project pricing requires a site visit and detailed scope assessment of the existing garage. While information is considered current at the date of publication, Superior Renovations isn’t liable for any decisions made solely on the calculator output.
Further Resources for your garage conversion
- Featured projects and Client stories to see specifications on some of the projects.
- Real client stories from Auckland
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