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Granny Flats, what you need to know.

Whether it’s for your elderly parents, teenagers, or an investment to rent out. A granny flat or second extension is most certainly a smart investment. This is our granny flat guide to building a granny flat – from working out viability, to how big you can build it and how to get the ball rolling. 

Can I build a granny flat on my property?

You can build a second dwelling if there are no easements (parts of your block that can’t be built on), housing codes, zones or restrictions on your block, and it fits within the 50% site coverage allowance. The site coverage allowance includes habitable AND non-habitable areas such as the house itself, garages, carports, balconies, eves, patios etc.

Converting a Garage or under house into a Granny Flat

This can be done so long as building standard are met, allows for 2.4m ceiling heights, the slab and you meet fire safety standards.

What does your Granny flat need to have?

Your granny flat must …

  • have at least one additional car space
  • be located within 20m of the primary dwelling
  • If built under hoe or garage conversion must have 2.4m ceiling height
  • share common services including water connection and meter, wastewater connection/system, street number and letterbox and driveway access
  • be located on a traditional 600m2 regular rectangle or square shape block

As of 26 September 2022 state and local restrictions about legally renting your granny flat have been removed. This has been amended to aid in the housing shortfall crisis.

How big can my granny flat be?

If you’re within your site coverage allowance of 50%, the size varies depending on where your property is. In suburban Sunshine Coast areas, we can build up to 8.5m high and 60m2 excluding non-habitable areas such as outdoor patio roofs, eve overhangs, window hoods, balconies, carports or garages. If you’re in a rural area – you have 90 m2 to play with. Or in you’re in the areas of Moffat, Shelly and Dicky Beaches, you’ll have just 45m2 and 4m high, for your second dwelling. 

Step 1: Talk to your local council.

Find out what is possible on your particular block by talking to council. They’ll be able to look up zoning information that tells you things like restrictions, controls, zonings and conditions that apply to the land. And how the land is able to be used. Your Building Designer / Architect, Certifier and Builder all need to know about these conditions for their part of the project so it’s highly important that this information is passed on.

Step 2: Get your block surveyed.

Provided a granny flat is allowable on your block, you need to work out where the existing structure sits within the site allowance. It also ensures that your primary dwelling is where it’s supposed to be before any working plans or submissions are created. Engage a professional to measure this for you.

If your block is on a slope greater than 15% you’ll need to also need an Engineer and get a soil test to analyse the stability and what engineering is needed to overcome it.

The structure needs to be at least 3m from the sewer main and 1m from the sewer connection.

Step 3: Obtain working house plans.

Once you have all necessary measurements including the current site coverage percentage, get granny flat house plans drawn up. These plans not only help the building approval, but they also help builders accurately price your project.

You can engage a Building Designer for plans, then an Interior Designer for the finished home complete with furnishings.  Or, alternatively, you can approach an Architect for the full package from working plans, specifications, colours, finishing’s and project management – basically everything. Your choice comes down to the budget.

Whomever designs your granny flat plans, they need the information gathered from council including restrictions, controls and conditions to ensure the plans are drawn up correctly from the beginning. This also avoids costly mistakes.

Once you have settled on a design and have your plans, you’re ready for the next step.

Step 4: Apply for development approval and any relaxations required.

In addition to complying with relevant planning requirements, building approval is required for all Secondary Dwellings. In the Sunshine Coast, building approvals are issued by private building certifiers. A permit for plumbing or drainage is also required, and plumbing approvals are issued by Council.

Contact the council to thoroughly investigate what is and isn’t possible on your land.

If you’re going to be over your site allowance with your granny flat, your best option is to apply for a council relaxation – although acceptance is not guaranteed. But worth applying for.

The building certifier will submit the building approval application with considerations for planning requirements, restrictions, controls and conditions on the block. While you wait, start researching and talking to builders.  

Are you planning to rent your granny flat out?

Are you looking for extra income? This is a great idea to cover costs until elderly parents or teens are ready to move in. If you wish to rent your granny flat to someone outside of your household, provided that your block has the right zoning, there can be one lease (for the Granny Flat) on the entire property and it must still share common services (water connection and meter, wastewater connection/system, street number etc).

If you plan to rent both the primary home and granny flat separately, contact the council to see if this is possible and you may need to submit a Development Application for ‘dual occupancy’ dwelling.

Step 5: Sign up the builder.

You can certainly start talking to builders before this point to work out who the best fit will be.  Try to educate yourself on what the acronyms all mean and ask plenty of questions. We have more on how to find the right builder here.

The builder will issue a building contract (usually HIA or Master Builders) and advise how the progress payments will be broken down. If you stick to the budget and the plans there should not be any price variations. 

Step 6: Practical completion and occupancy certificate.

Once the build is completed and any defects are addressed the builder will issue the last contract stage of Practical Completion. The certifier will do the final inspection and once passed you’ll receive your occupancy certificate – which means you are free to move it.

We’re a local Sunshine Coast builder happy to share our knowledge and insights in this Granny Flat guide. Please feel free to continue reading our blog section.
Or if you would like a quote for a Granny Flat, please get in touch