Guide To Converting Your Garage To A Granny Flat In New Zealand

We’ve been getting quite a bit of requests recently about building a sleepout, extending the house, adding another level and converting a garage to a new living space. So we’ve put together this article to answer a few questions, and to provide some advice to those exploring this idea.

Life is full of changes, and our needs often shift along with it. If you’re considering converting your garage into a living space, it’s likely because your current situation calls for it. Perhaps moving isn’t a viable option due to your love for the location and your home, the high costs of buying a new place, or an unfavorable housing market.

Turning your garage into a new living area isn’t a straightforward decision and requires careful consideration. That’s why we’ve put together this article to help you think through the important questions, ensuring you make an informed choice.

To begin, how do we define a “Granny Flat”?

Based on what we found on – A “granny flat” is a small, self-contained, and detached dwelling typically located on the same property as a larger, primary residence. These units are designed to provide independent living space for one or two people, often used by elderly family members or as rental units to generate additional income.

As our circumstances evolve, so do our needs and desires. Just because something seems less useful now doesn’t mean it won’t be invaluable later. When you bought your house, you probably spent a lot of time finding the perfect one. But now, you might need more space for a growing family or a dedicated home office. Converting your garage into a granny flat or living area is a popular solution for many reasons. It’s an excellent way to maximize your existing space without the hassle of moving. However, there are several factors you need to consider to make sure it’s the right move for you.


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Is My Garage Suitable to be Converted into a Granny Flat?

Converting a garage into a granny flat can be a great way to create additional living space. However, before starting the conversion, it’s essential to determine if your garage is suitable. Here are some key factors to consider:

Ceiling Height

  • The ceiling height must be more than 2.4 meters. Many garages have lower ceilings, so this is an important measurement to check.

Weather Resistance

  • Garages are typically designed for vehicle storage and may not have adequate weatherproofing. Ensuring proper water drainage and insulation is crucial to prevent water ingress and moisture buildup.

Structural Integrity

  • Assess the structural condition of your garage. It should be in good repair and capable of supporting the modifications required for a living space.

Building Code Requirements

  • Check local building codes and regulations. In New Zealand, the conversion must comply with the Building Act 2004 and the New Zealand Building Code.

Utility Connections

  • Consider the availability of utilities such as electricity, plumbing, and heating. These are essential for a habitable living space.

Accessibility and Safety

  • Ensure the garage can be safely accessed and meets fire safety standards, including adequate exits and smoke alarms.

Council Consent

  • You will likely need to obtain consent from your local council. This can include resource consent and building consent.

Additional Considerations

  • Think about parking space, as converting your garage will eliminate its original use. Alternative parking solutions may be required.


Checklist for Converting a Garage to a Granny Flat in New Zealand

Requirement Yes No
Ceiling height > 2.4 meters [ ] [ ]
Adequate weather resistance [ ] [ ]
Structural integrity [ ] [ ]
Compliance with Building Act 2004 [ ] [ ]
Utility connections (electricity, plumbing, heating) [ ] [ ]
Accessibility and safety standards [ ] [ ]
Council consents (resource, building) [ ] [ ]
Alternative parking solutions [ ] [ ]

Use this checklist to assess the suitability of your garage for conversion into a granny flat and ensure compliance with all necessary regulations and requirements.


Here’s is what you can expect as a step by step process to converting your garage to a granny flat

Keeping in mind, steps will differ dependant on site conditions/existing property structure and client requirements. Converting your garage into a granny flat is an excellent way to add value to your home and create additional living space. Whether you’re looking to accommodate a family member or generate rental income, a garage conversion can be a smart investment. Below is a step-by-step guide to help you navigate this process smoothly.

Step Description Parties Involved
Step 1: Assess Feasibility Evaluate if your garage is suitable for conversion. Check local zoning laws and regulations to ensure the project is permissible. Consider the structural integrity, size, and layout of your garage. Homeowner, architect & structural engineer
Step 2: Budgeting Create a detailed budget that includes all potential costs such as design, permits, construction, utilities, and furnishings. Include a contingency fund for unexpected expenses. Homeowner, financial advisor, renovation company
Step 3: Hire Professionals Engage an architect or a reputable renovation company (who has architects they work with) to help plan the conversion. Consult with a structural engineer if necessary. Homeowner, architect, structural engineer, renovation company
Step 4: Obtain Permits Apply for the necessary permits from your local council or planning department. This may include building permits, electrical permits, and plumbing permits. Homeowner, local council, architect, renovation company
Step 5: Design and Planning Work with your architect or designer to create a detailed plan. Consider the layout, plumbing, electrical, heating, and cooling needs. Plan for windows, insulation, and soundproofing. Homeowner, architect, designer
Step 6: Prepare the Garage Clear out the garage and remove any items. Address any existing issues such as cracks, leaks, or pests. Ensure the garage floor is level and in good condition. Homeowner, contractor
Step 7: Construction Begin the construction process. This includes framing, insulation, plumbing, electrical work, and installing windows and doors. Monitor the progress and ensure all work meets the required standards. Renovation company and contractors (plumbing, electrical, carpentry), homeowner
Step 8: Interior Finishing Finish the interior with drywall, flooring, and painting. Install kitchen and bathroom fixtures if applicable. Add lighting, heating, and cooling systems. Renovation company,  homeowner
Step 9: Final Inspections Schedule final inspections with local authorities to ensure all work complies with building codes and regulations. Address any issues identified during the inspection. Local council inspectors, renovation company, homeowner
Step 10: Furnishing and Decorating Furnish the granny flat according to its intended use. Add personal touches and decorations to make it a comfortable and inviting space. Homeowner, interior designer (optional)
Step 11: Enjoy Your New Space Once everything is complete, move in or rent out the granny flat. Enjoy the added value and functionality of your home. Homeowner

Converting your garage into a granny flat can be a rewarding project, providing additional living space and increasing your property value. By following these steps and working with experienced professionals, you can ensure a successful and smooth conversion process. Take the time to plan thoroughly and enjoy the benefits of your newly transformed space.

Is converting the garage into a granny flat the right choice?

Firstly, what is a granny flat? Auckland City council doesn’t have a separate category for granny flat or minor dwelling units, but it simply means any flat that has a kitchen is considered to be a second household unit.

Why you need extra space? do you need a room for your child or parent? Perhaps you’re looking to rent out the un-used space? If you are just seeking extra space (with the kitchen or bathroom), then adding an extension to your home could also be an option.

There could be other reasons for the extra space, and it may not be a granny flat that you’re needing. It is common in new homes to have a media room, study room/office, recreational area, or a game room – all of which is not considered a second household unit.

You need to determine what kind of room you’re looking for, whether it’s an extra household unit, extra bedroom, a study room, or a recreational room – this will determine the scope of works for the architect.

There are multiple ideas available to use spare space. You can convert your garage into following areas:

  • Work from the home area
  • Gym area
  • Gaming area
  • Hobby room
  • Media room or movie theatre
  • Teenager’s room
  • Guestroom
  • Rented out for extra income
  • Home entertainment/bar space

A garage conversion is a place that offers quite a wide range of possibilities and because it’s a existing building/space – it requires less planning and investment compared to a new extension. But before you explore ideas, you need to consult with  an architect to see is there are any limitations.


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Can I add a toilet in my garage?

The addition of a toilet to a garage in New Zealand can be a valuable improvement, creating a convenient bathroom for a granny flat or workshop space. However, it’s crucial to address potential drainage challenges before embarking on this project.

The Building Code of New Zealand emphasizes the importance of proper drainage systems. Toilets function optimally with a downward slope that allows waste to flow by gravity into the main sewer line. Garages, particularly detached structures, often lack this natural slope, presenting a significant hurdle.

As highlighted by the Auckland Council website, creative plumbing solutions might be necessary. Since the existing garage floor likely doesn’t possess a downward gradient towards the sewer line, potential solutions could involve:

  • Breaking through concrete slabs.
  • Digging trenches.
  • Utilizing a pump system to facilitate waste movement.

While these solutions may require additional effort, adding a toilet to your garage in New Zealand remains achievable. It’s recommended to consult with a Licensed Building Practitioner (LBP) plumber to discuss the feasibility of your project and explore the most suitable drainage strategy for your specific situation. Their expertise can ensure a compliant and functional toilet installation in your garage.

Converting an Attached vs. Detached Garage

There are key differences to consider when tackling an attached garage conversion compared to a detached one. Understanding these variations can streamline the process and ensure a successful project.

Building Code Considerations:

Both attached and detached garage conversions must comply with the Building Code of New Zealand . This code outlines safety and performance standards for alterations and additions to existing structures. While the core principles remain the same, there might be slight variations depending on the specific project details. Consulting a Licensed Building Practitioner (LBP) is highly recommended to navigate the intricacies of the Building Code and ensure your conversion adheres to all regulations.

Resource Consent Requirements:

The need for a Resource Consent from your local council can differ based on the type of garage conversion you undertake. The Auckland Council website provides valuable insights into this process. Generally, attached garage conversions are less likely to necessitate a Resource Consent compared to detached ones. This is because attached structures have a smaller impact on the overall building footprint and may not significantly alter the property’s visual character.

However, it’s crucial to confirm the specific requirements with your local council. Factors like the size and scale of the conversion, potential changes to the building exterior, and the impact on neighboring properties can influence the need for a Resource Consent.

Project Complexity:

Converting an attached garage often involves less structural work compared to a detached structure. Since the attached garage already shares walls and potentially the roof with the main house, modifications might be primarily focused on interior elements. This can potentially lead to a faster and potentially less expensive conversion process.

Detached garages, on the other hand, might require more extensive structural changes to integrate seamlessly with the existing house. New walls, roof connections, and potentially foundation work could be necessary, depending on the desired outcome.

Impact on Existing Services:

Both attached and detached garage conversions might necessitate adjustments to existing utilities like plumbing, electrical wiring, and HVAC systems. However, attached garages often benefit from easier access to these existing services within the main house. In contrast, detached garage conversions might require longer runs for plumbing and electrical lines, potentially adding to the project cost and complexity.

While both attached and detached garages present exciting conversion possibilities, understanding the key differences can help you make an informed decision. Consulting with an LBP and your local council regarding Building Code compliance and potential Resource Consent requirements is crucial for a smooth and successful conversion process.

Other considerations

Here are a few other things to think about as well before you jump into it:

  • Where will you park your vehicle if the garage gets converted into the room?
  • What would the house look like after the transformation?
  • How spacious or large is your garage? Is it worth a conversion or is it just the waste of time, effort and money?
  • Do I require building consent for the garage conversion?

Does a garage conversion require building consent?

You will need to first consult with an architect to carry out a feasibility study which will determine whether it’s even possible to utilise the garage space.  For a basic garage conversion to a living space, you will require building consent because the garage is not considered a habitable space. Bathrooms are allowed if they meet the rules, but you can’t put a kitchen and laundry into a basic conversion.

All the work that needs to be done to convert your garage into a living room must also be done in accordance to the standards set out by the building code. A garage being a non-habitable structure is a Class 7.0 residential outbuilding. So when you decide to transform it into a living room which will be habitable, then it will be reclassified into Class 2.0.

However, if you are thinking about converting your garage into a minor dwelling (second household unit), then you will be both building consent and resource consent. Resource Consent is required to ensure the project meets the provisions of the Resource Management Act, which for buildings are usually covered by the District Plan -or in Auckland, the Unitary Plan…. Building Consents are required to ensure the project meets the provisions of the Building Code. (Reference from Pacific Environments)

If you are living in or near Auckland, then it is important to determine your zone before seeking any permission to convert. The rules might vary according to the zone, and you need to be certain as to what rules apply when it comes to change in the use of a building or the development of an extra dwelling – your architect will be able to help you with this.

The Auckland Unitary Plan has set the ground rules for all kinds of future developments, expansions, and intensifications covering Auckland and the nearby areas. This unitary plan focuses on the rules to control how the areas must develop in the future.

To determine the details about your zone, all you need to do is to go to the Auckland council site and search for your zone. You will find all the details regarding your zone available on the following website:

The New Zealand government is considering changes to make it easier to build granny flats. The proposal would allow for the construction of granny flats up to 60 square meters without needing a building or resource consent, provided they meet certain criteria. This initiative aims to increase the supply of affordable housing and support multi-generational living arrangements. The proposed criteria for these units include aspects of building performance, safety, and environmental impact​ (Building Govt)​​.

We still highly suggest talking to your architect, or a planner to get the best possible advice. Getting all the information regarding your zone and the building rules that applies to you will help avoid all kinds of future complications and conflicts.

What Features Of Building Code Do I Need To Keep In Mind?

  • Fire Safety: The fire safety feature encourages to take measures regarding fire accidents, including the construction of safe escapes and installation of smoke alarms.
  • Energy efficiency: The use of natural resources to provide for comfort is also a clause in the Code. You have to introduce adequate lighting, humidity, and ventilation sources to comply with the requirements.
  • Durability: The durability feature stress that the material needs to be used in the building will stay functional until the estimated life of the building.
  • Sanitary measures: You must have to pay attention to all kinds of sanitary fixtures, including water, gas, and electricity.
  • Moisture prevention: You must have to keep an eye on the drainage system for all kind of penetrating and pouring water.
  • Ceiling height: One of the most crucial factors in building a room is the ideal height of the roof. The height of the living room must not be less than 2.4 meters. If the roof of your garage is lower than 2.4 mark, then you may consider raising the ceiling. Lowering the floor could be an option, but it requires more effort and investment.

If the walls of the garage are made of brick then it will require an additional layer of protection using membrane or the weather-resistant paint. The additional membrane will help provide protection against dampness. You can also opt in stud wall if you’re looking to secure electrical wiring and insulation.

In regards to the floor of the garage, you have to ensure that it has waterproof protection to avoid dampness and water retention. The floor of the garage is mostly commonly made of reinforced concrete, and wouldn’t have any additional protection. There are a variety of products available in the market that can help you with waterproofing the floor.

Another thing to consider is ventilation, you may want to introduce more air flow and ventilation by choosing to install a large window replacing the garage door. The requirements for the natural light in the living room have been pen down in the clause G7 of the Building Code. You can measure your natural light requirements using a lux meter.

The room will also require additional electrical outlets, which most registered electricians will be able to do. Make sure to Hire a registered electrician because they will need to provide the necessary compliance certificate regarding all the wiring work that has been done – which will be needed when you’re applying for your Code of Compliance Certificate.

You’ll also need to be aware that converting your garage into a habitable room, you will also need to look at issues with the rainwater. Most of the garages use a slanted floor to drive rainwater outside the garage into the drain. But once you decide to convert the garage into the living area, you’ll need to address the water flow issue – perhaps installing additional drains.

Unconsented garage conversions

If garages are converted into living spaces without the appropriate consents and certifications, future owners of the property may have problems insuring the property – even if a pre-sale building inspection identifies no issues.

It may, therefore, be difficult to sell the property – at best, there could be a delay before a sale and purchase agreement becomes unconditional.

We recommend that you advise your clients to contact the council and apply to have any unconsented conversions certified before they list a property. This will save time and stress during the sale process. (Reference from

Converting a garage into an additional dwelling

Converting a garage into an additional dwelling can be an exciting project with numerous benefits and motivations. People are increasingly looking at their garages as potential living spaces, and for good reason. First and foremost, turning a garage into an additional dwelling can be a great way to generate extra income. Whether you decide to rent it out long-term or use it as a short-term rental on platforms like Airbnb, the financial benefits can be substantial. This additional revenue can help offset mortgage costs or provide extra funds for other expenses.

Another reason people pursue this conversion is to accommodate multi-generational living. With rising property prices, many families are finding it difficult for younger generations to move out or for older family members to downsize. Converting a garage provides a convenient and cost-effective solution, offering independence while keeping family close.

Homeowners also find that converting a garage adds significant value to their property. A well-executed conversion can increase the overall market value of the home, making it a wise investment. Potential buyers often see an additional dwelling as a versatile space that can serve various purposes over time.

The flexibility of an additional dwelling is another compelling reason. It can be used as a home office, a guest suite, a studio, or a living space for teenagers or elderly parents. This adaptability ensures that the space can meet changing needs over the years, providing long-term benefits.

From a lifestyle perspective, having an additional dwelling can enhance privacy and comfort. It allows for separation of living spaces, which can be particularly useful if you have frequent guests or if family members need their own space.

Of course, the process requires careful planning and adherence to local regulations. In Auckland, for example, you’ll need resource consent and building consent from the Auckland Building Council. This ensures that the conversion meets all safety and construction standards, providing peace of mind.

Ultimately, converting a garage into an additional dwelling offers a blend of financial, practical, and lifestyle benefits. Whether you’re looking to increase your property’s value, generate income, or create a flexible living space, this conversion can be a highly rewarding project​.

Benefits To Creating An Additional Dwelling
Generate Extra Income Rent out the space long-term or as a short-term rental (e.g., Airbnb). Helps offset mortgage costs or provides extra funds for other expenses.
Accommodate Multi-Generational Living Convenient and cost-effective solution for younger generations or older family members. Provides independence while keeping family close.
Increase Property Value Well-executed conversions can significantly raise the market value of the home. Seen as a versatile space by potential buyers.
Flexibility and Versatility Can be used as a home office, guest suite, studio, or living space for family members. Adaptable to changing needs over time.
Enhanced Privacy and Comfort Separate living spaces can be useful for frequent guests or family members needing their own space.
Adherence to Local Regulations Requires resource and building consent from local authorities (e.g., Auckland Building Council). Ensures the conversion meets all safety and construction standards.

What does converting a garage to a extra house unit mean Financially?

Adding a self contained unit, or ‘granny flat’ to your home can be a cost effective way to provide a home for elderly relatives or older children struggling with rising rent. It can also be a great way for homeowners and investors to generate extra cash flow through rental income and increase the property’s overall value.

With rental yields of anywhere between $200-$600 a week, granny flats can be a great strategy if you’re looking for a long-term return on investment. Not only do they provide a second income, you can also benefit from positive gearing and extra claimables on your depreciation schedule. In an area where rental demand is high, a granny flat can stand out from the competition when it comes to selling. (Referenced from Loan market, 2017)

Attached or detached? 

Your ‘granny flat’ can either be a stand-alone dwelling or an extension of your house (e.g. if you convert your garage or your basement).

Factors To Consider While Opting For a Garage Conversion

Although the garage will work just perfectly with your existing space, you have to make some necessary alterations to make the new room blend in with the rest of the home.

  • Replacement for a garage door: Replacing the large garage door is a must, there are plenty of options available when it comes to door replacement, including a window, wall, or a patio door.
  • Is there enough lighting? Where is it coming from? If the garage already has a window, then replacing the garage door with extra windows will also offer you extra lighting. Even if there is no sufficient source of natural lighting in the room, you can always opt for artificial skylights as well. The lighting choice in the newly converted room depends on your usage of the room.
  • What about the garage floor? Mostly garages are concrete flooring, and if you are planning on using the room as the gaming area or the media room, you can opt for standard carpet or wooden floors. However, if you are thinking about converting your garage into a guest room or granny flat, then your options may lean more towards comfort (eg extra layer of insulation under the carpets)
  • How to utilize the space? If you are planning to convert the garage into a small dwelling or a granny flat, utilising the given space will be important and it’s balance between necessary functions and space. For example, if it’s a small space, it may be better of going for a open plan kitchen, living area and laundry – as opposed to partitioned off.
  • Where to park the car? The consequence of transforming a garage into the habitable living room is the loss of parking area for your car.

An example of a converted garage

garage-conversion, Kitchen Renovation, Bathroom Renovation, House Renovation Auckland

What is the cost to build a granny flat (nz) detached?

The cost of building a granny flat detached from the main house can vary quite a bit, and the 3 main factors it comes down to are the size of the build, your region, and the complexity of the build/materials. There are of course cheaper options as opposed to building from scratch such as kit sets or prebuilt granny flats. If you are intending to build from a plan, the average price for a granny flat starts around $120,000 plus GST and can go up to $180,000 mark, plus GST.  


How much does it cost to convert a garage into a room?

The cost of building work for converting a garage to a room can average around $1,250 – $1,500 per square metre not including the cost of architect fees, building/resource consent fees, excavation and engineer fees. Typical garage conversion to room (30m2) will range from $47,500 – $55,000 (without kitchen/bathroom)


How much does it cost to convert a garage to a granny flat?

The cost of building work for converting a garage space to a granny flat which includes a new kitchen and bathroom ranges from $1,750 – $2,150 per square metre not including the cost of architect fees, building/resource consent fees, excavation and engineer fees. Typical garage conversion to granny flat (30m2)  will range from $82,500 – $124,500.  A minor dwelling can cost up to $20,000 in plans, consents, and development contributions and connections before any building work takes place.

If you’re still deciding what to do with the unused space, make sure to consult with professionals (architects, builders/project managers, and financial advisors) as well to get different perspectives on the situation so you can make an informed decision that will benefit you in the long term.


Curious about the Cost of Converting Your Garage?

Try Our Cost Calculator Tool for a Quick Estimate

Open Garage Conversion Cost Calculator here



Please note: Whilst all information is considered to be true and correct at the date of publication, changes in circumstances after the time of publication may impact on the accuracy of the information. The information may change without notice and Superior Renovations is not in any way liable for the accuracy of any information printed and stored or in any way interpreted and used by a user.


To wrap up

How much does it cost to convert a garage into a room?

Typical garage conversion to room (30m2) will range from $80,500 – $90,000.

How much does it cost to convert a garage to a granny flat?

Typical garage conversion to granny flat (30m2) will range from $90,500 – $120,500.

Do I need building consent for converting my garage to a granny flat?

You will need to apply for building consent if you're converting your garage to a room, if you're converting it to a minor dwelling (with kitchen and bathroom) then you will also need to apply for resource consent.


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