How do you legalize garage conversion?

Have you considered a garage conversion to create that home office, spare bedroom, playroom or even a granny flat? Converting a garage can be an inexpensive way of getting the extra room you need, but there’s more to it than removing your car and adding some furnishings and fixtures. 

Check out our range of garage renovations here. 

Do I need a building consent for the conversion work?

A garage is a Class 10a building and is considered a non-habitable structure as set out in the Building Code of Australia (“BCA”). Converting a garage to a habitable room is a reclassification to Class 1a. It will therefore require a Development Application and Approval from your local Council before the commencement of any work.

Garage Conversion

Is a Permit Required to Convert a Garage?

Since you are changing how space will be used, you will most likely need building permits, though this can vary by location. To apply for garage conversion permits, contact your city’s Zoning Department for more information. You may need to work with an architect to provide a proposed floor plan when applying for a permit.

Permits will ensure your plans meet building codes and local ordinances for living spaces. Building codes may dictate the minimum number of windows in a space, the number of exits and entrances, the height of the ceiling, the number of outlets and other factors. If you cannot meet any of these requirements, you may be able to apply for a variance depending on the issue.

Garage conversion permits can range in cost, but the average price is often between $1,000 and $1,500. Expect to pay more if you need to apply for a variance.

Be aware, some city ordinances or homeowner associations may require a certain amount of covered parking that could prevent you from converting your garage.

If your space requires a permit, it will also require an inspection at the end of the renovation to make sure you have met all building code and zoning requirements.

Council Approval

Because you’re converting a non-habitable space into a habitable room, you will need council approval to convert your garage in most states and territories. This will probably start with development approval. Council will want to know that the work you have done will meet Building Code Australia (BCA) standards for dwellings and any additional council requirements. If you’re thinking of converting a garage into a granny flat, you also need to know about Granny Flat Regulations.

To get approval, you will need to supply the council with preliminary and final plans. A good drafter can provide you with the plans and may be able to help you through the approval process.

What are the main factors I need to take into consideration?

However, there are certain things you need to keep in mind should you decide to convert your garage.

Is your garage suitable for conversion?

It is essential to know if the height of the room will comply as a habitable room. Once a floor has been laid, the minimum height of this room to the ceiling will need to be 2.4metres.

The next most important question is, is your garage waterproofed. This is not normally necessary when used to park your car or store tools and bikes. The fall of your driveway may be directing the rain run-off towards your garage where mostly there will be a drain or at least a gap in the concrete to act as a drain. The concrete slab in the garage is not normally laid to the same waterproofing standards as the rest of your home, so there may be a risk rising damp. One way to rectify this is to add a concrete slab and membrane over the existing slab.

When is Converting Garage to a Room a Good Option?

If you’re looking to add living space to your home without starting from scratch, converting a garage to a room is an option to consider.

A garage remodels the right option for your home, if:

  • The garage door is easily replaceable for your space: Will your new living space allow for patio doors or an additional entrance where the overhead door used to be? If not, make sure you can blend the new wall into your current home exterior and create a wall that doesn’t look like it used to be a garage.
  • Heating and cooling are in your budget: To keep costs down, find out if your current HVAC system will support an additional room. If so, you can expand the ventilation to cover the garage. If not, you can update the system or purchase an independent system to provide a heating solution in the garage, but you’ll need to make sure you can afford one of these options.
  • Plumbing is accessible (if necessary): If you’re hoping to add a bathroom or kitchenette to make your garage conversion project into an in-law suite or apartment, start with contacting a plumber. Adding plumbing lines, specifically, drainage is often the most expensive part of a garage makeover and could be outside your budget.
  • Adequate parking and storage are available elsewhere: Converting your garage means permanently eliminating parking and storage. Turning the garage into extra space will not be worth the investment if you no longer have a place for your lawnmower, toolbox or have insufficient or unreliable parking.

Determine why you want to convert your garage

Consider the space, or function of the space, that you require so that you obtain the best advice. Do you want a recreational room, studio, granny flat or a cabana beside the pool?

Making an extension to your house or a first-floor addition may be a more effective way to obtain the extra space you are seeking. Most likely, this will provide you with a much higher quality of living.

In addition, excavating or removing the garage floor to lower it, to meet the height restrictions, can be quite costly. Raising the roof and ceiling is not always feasible due to construction limitations.

Ceiling height is a key factor in meeting the BCA requirements of a habitable room. The minimum ceiling height for a garage is just 2.1m whilst your new habitable room needs to have a ceiling height of at least 2.4m. In situations where the ceiling height is less than 2.4m, raising the roof is often the only option as the concrete slab of a garage floor can be both costly and difficult to remove.

Garage walls are typically single brick and will need to be sealed using a waterproof membrane or waterproof paint to reduce the likelihood of rising damp. The addition of a stud wall can act as housing for the electrics and insulation. This can then be finished with plasterboard and your paint colour of choice.

If the concrete slab has not been built in accordance with residential slab BCA standards, then the entire area beneath the concrete slab must be treated with a termite management system. Variations apply to the National BCA termite risk management provisions throughout Australia, so you will need to check the requirements of your State. There must be evidence of a waterproof membrane beneath the slab. If not, you will need to waterproof the slab using one of the many commercial products available for this purpose. These can be rolled or brushed on and will prevent moisture from entering the room from the ground up.

Details of compliance with the energy efficiency provisions of the BCA must be submitted as part of your Development Application or Application for Consent. In NSW, this is The Building Sustainability Index (BASIX), and in other Australian states, it is the Nationwide House Energy Rating System (NatHERS). These schemes aim to determine buildings thermal comfort and the need to heat or cool the building to keep the occupants comfortable.

Replacement of the existing garage door with a large window will ensure the room benefits from plenty of natural light and meet the requirements of the BCA. The room must have a window opening that has an area, which is 10% of the floor area of the new room.

A licenced plumber or electrician must carry out all plumbing and electrical work. They can provide you with the necessary Certificates of Compliance. If the room is to be used as a bedroom, a smoke alarm must be installed in that room.

Quite often the fall of a driveway is on a slant with rainwater running into a drain at the end of the driveway and in front of the garage door. This should be addressed during your design process to ensure rainwater is diverted away from the habitable space.

As the garage can no longer house your car, it is a requirement of some States, that an additional on-site parking spot must be available to replace the now-defunct garage parking.

Hitch Property Constructions has the biggest range of the garage renovations Melbourne. Check it out here.

Consider the costs

Converting an existing garage or carport into a rumpus or games and party room is a cheap way to gain some additional floor space and provide some privacy for Teenage children when they entertain their friends. Planned and executed properly, it will add value to your house. A double garage is especially good for this as this space is usually 6mx6m and often under the main roof. A garage is classified as a class 10a structure under the BCA, and by changing its use to a habitable space, its class needs to be changed to class 1. Class 1 structures have a much more stringent set of requirements than class 10a. Complying with these requirements is at times tricky, and sometimes creative solutions are required. What seems a simple task requires a good deal of knowledge about planning regulations and the Building Code of Australia if a good outcome is to be achieved. On several occasions, I have been brought in to re-document garage conversions that have been started without proper documentation or approval.

Disputes with neighbours will often result in stop-work orders issued by Local Council. The building is only allowed to re-commence after providing retrospective documentation. The remedial works required to gain compliance far exceeded what these Clients had tried to save. One common problem encountered is that the minimum allowable ceiling height for a living area is 2.4m. Often garages have less than this. Alternately they may have 2.4m, but the floor level is set down to allow car access. This is a problem as living areas have minimum requirements for floor height above the adjacent ground level. If the floor is raised to comply, then the ceiling does not.

Another problem is that there may be no white-ant treatment or damp proof membrane under existing Garage or carport slabs. The remedial work required to resolve these shortcomings may be difficult to achieve without serious structural changes. Most jobs require a new topping slab as this means complying white-ant treatment and damp proof membrane can be installed. Most Councils have planning regulations that require a minimum of 1 under-cover car-park per dwelling. If you are converting your garage to a living space, then you need another under-cover car-park elsewhere. Building a new carport in front of the existing house to provide a new under-cover park is usually not allowed as most Councils have specific planning rules prohibiting this form of development. Double or triple Garages are usually the easiest to work with as the simple solution is to put up an internal partition dividing the space so that one (complying) car-park is retained. Garages and carports are also quite often on or near boundaries. Development on a boundary is always problematic as it raises the issue of Fire-resisting construction and minimum setback rules. Each case is unique, and it is advisable to gain professional advice before commencing. 

A DA can seem quite expensive if the size of the project is quite small. The reports and documentation required for a DA for a garage conversion cannot be ignored, as the level of information required may be similar to that required for a large extension.

Suppose you are one of the fortunate ones with sufficient height of at least 2.4 metres inside your garage and you are able to successfully waterproof the garage. In that case, converting your garage could be less expensive than building an extension.

What Type of Room Can a Garage Become?

Your project is completely customizable. As long as you obey building code requirements, you can create any type of living space with your garage remodel. Depending on the zoning of your home, you may hit more hurdles when attempting to build an independent living space, such as an apartment, than you will when converting your garage into a single room.

Garage conversion ideas include:


Studio Apartment or In-law Suite


Art studio


Family room

The only limitations you have when converting your garage to living space are those set upon you by local regulations and budgetary restrictions.

Looking for Melbourne garage renovations? Look no further. Hitch Property Constructions has you covered.

Garage Conversion Essentials

The typical garage has a concrete floor, outer walls, a roof and usually a window. In order to convert it into a habitable dwelling, it will need more. You will need to replace your garage door with a more appropriate replacement door for starters, and for light and ventilation, you will also want more windows. Other things that you will probably need to include in your costings are:

  • Flooring
  • Waterproofing
  • Insulation
  • Interior walls
  • A ceiling or roof interior lining
  • Heating and cooling
  • Lighting

Since garage floors are not elevated, you will also have to make sure water cannot enter the converted space. You may need to install an elevated floor and get a drainage expert to divert water away from the interior.

The driveway leading to your converted garage will probably look out of place. A little landscaping can help with this, and you may also want to consider diverting your existing driveway to a designated parking space and installing a carport.

Whether you’re going to be using your garage as a spare bedroom or home office, you will need an electrician to install power points and lighting fixtures. If you are converting the garage into a granny flat or want it to be a self-contained living space, you will also need to have plumbing installed. If you are going to rent it out as a granny flat, it will need to have a bathroom and cooking facilities as well.

When you add up all the costs, you may discover that a garage conversion is more expensive than you thought it would be. For example, converting a garage into a playroom or home office with electricity and air conditioning but not plumbing can cost around $10,000 to $15,000. Add plumbing for a bathroom and kitchenette, and the price will be much higher.

Don’t forget, though, that building from scratch would be far more expensive. Done right, a garage can become a wonderful living or working space and can even provide you with added income if you convert it into a granny flat. Just be sure you get professional help and do the job right. It will be worth the extra expense if you don’t cut corners by leaving out the inclusions that make it safe, comfortable and hygienic.

Before making a final call, consult with contractors and other professionals to determine whether a garage conversion is the best way to accomplish your space-enhancing goals efficiently, safely and with the value of your home intact.

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