Everything You Need to Know Before You Build Your Secondary Dwelling

February 24, 2021

If you or your family are thinking about building a secondary dwelling on your property, then it’s crucial to consider every element of what may be involved from start to finish, and what to expect from the process. In the excitement of wanting to keep your family close with a Granny Flat, it can be tempting to simply rush ahead with a builder without a planning report on your land - assuming that everything will somehow work out. We’ve all heard these horror stories, and being left with a half-built project and tens of thousands of dollars lost is a situation we all want to avoid.

In this article, we have put together a Secondary Dwellings Fact Sheet, to outline everything you need to know before you build a secondary dwelling in 2021 on your land:


Is it Complicated?

Not all Granny Flat projects are made equal! To determine the exact cost of a Granny Flat is difficult because every piece of land is different, and every homeowner’s needs and desires are different too – and therefore, must be considered in their own individual light. There are many elements considered as part of a development assessment, such as the proposed position of a Granny Flat on your property, as well as the requirements, rules, restrictions and regulations of the local council area in which you live.

Complying Secondary Dwelling Developments in NSW

The NSW government defines a Granny Flat or secondary dwelling as ‘self-contained accommodation within, attached or separate to an individual home’. While it is true that many properties in NSW will comply for the construction of a Granny Flat, not all properties are ideal. Typically, in order for your Granny Flat to be built it must be;

  • Established in conjunction with another dwelling (the main house)
  • Built on the same block of land as the main dwelling (rather than being an individual lot as part of a strata plan)
  • A Granny Flat can be within, attached to or separate from the principal dwelling.
  • Interested in building a Granny Flat attached to your existing home?

Before commencing any build, Cubitt’s conducts a detailed development assessment of your property in line with local planning restrictions, providing transparency and peace of mind for our customers. For more information on NSW planning requirements, see the NSW Planning Portal website in references below.

Here are some common considerations that can affect the secondary dwelling approval process, but have all been managed by Cubitt’s to get projects council approved:

Designated Bush Fire Prone Areas

New South Wales and the ACT are loved by Australian families for being filled with bushland and expansive National Parks. However, this beautiful bushland can also mean that it poses a risk for bushfire, and a surprising number of suburbs are within these bush fire zones. Any proposed construction in bush fire areas must comply with Planning for Bush Fire Protection for new works. You can find out if your land is within bushfire prone area via the: NSW Rural Fire Service website.

Flood Zones

Australia is famous as the land of drought and flooding rains. When building a secondary dwelling on your land, it’s important to plan ahead and consider if any of your property is at risk of flooding. Flood zones are an important consideration in the approvals process, affecting parts of NSW such as the Hunter Valley and Central Coast, parts of Wollongong, Newcastle and Windsor to name a few. In general terms, the requirement is that the Granny Flat must comply with the Building Code of Australia, and your project must have a particular certificate to demonstrate this. When you choose to build with Cubitt’s, we will handle the approvals process for you, and keep you updated throughout the building journey.

Snowfall and Sloping Blocks

The likeliness of snow falling in the winter months in the Southern Highlands such as Bowral and Mittagong, as well as the Blue Mountains, means that bolstered roofing may be required. While beautiful, the Great Dividing Range that stretches along Australia’s east coast does mean that there are many steep sloping lots of land throughout NSW, particularly in the Greater Blue Mountains area such as Blaxland, Katoomba and Lithgow. Specialised construction methods and approvals are required to reduce any risks posed by steep land. Cubitt’s are experts at navigating difficult blocks and have the expertise needed to build split-level Granny Flat designs where required.

Stormwater Drainage on Flat Land

Usually large, flat blocks of land are typically considered a goldmine for any sort of construction project, like building a Granny Flat or detached secondary dwelling. But land such as this found in Leppington or Blacktown, can adversely be affected by a lack of fall, resulting in inefficient disposing of stormwater.

Subdivided Land and Smaller Blocks

With space at a premium in the Greater Sydney region and indeed NSW more widely, smaller blocks of land and subdivided lots are becoming more common. If you live in Sydney’s inner western suburbs such as Marrickville, Newtown and Strathfield, you may have always believed a Granny Flat would never be possible on your land – think again! There are options for smaller blocks to gain council approval and build a secondary dwelling, speak with one of Cubitt’s expert consultants to learn more on 1300 721 150.

Local Council Infrastructure Contributions

Also known as ‘developer contributions’, local councils charge monetary contributions towards local infrastructure when a new building development occurs. This contribution is administered by the local government and is allocated towards anything from parks, community facilities or footpaths to name a few. While two suburbs may be geographically close to each other, it’s important to note the contributions policies may differ greatly – so it’s a good idea to check. However, when you build with Cubitt’s, our planning and development experts will investigate this for you.


Building in the ACT – It’s Different from NSW!

There are a number of elements you will need to check for your block of land if you are planning construction. Firstly, particular planning controls apply to certain blocks of land. Use the ACTmapi to find out which Territory Plan zone your property is in and what type of development is permitted.

Before building in the ACT, you will also need to ensure that utility network providers have access and enough room to bring in equipment and repair infrastructure. If not, and your building is too close, you may be liable to pay for the infrastructure to be moved or you may have to remove whatever is causing the obstruction – which can cost thousands of dollars. For water and sewerage utilities, you can contact Icon Water. For electricity and gas utilities, the best contact is Evo Energy. For any Granny Flats or home extensions built with Cubitt’s, our team will investigate all development planning for you, and handle the entire application process from start to finish, to ensure a relaxed experience for our customers.

Other considerations before building in the ACT include checking if there are any lease and development conditions on your land, discovering if there are any heritage considerations, confirming where the plumbing pipes of your property tie into the main system, as well as making sanitary drainage plans for the secondary dwelling.

If you would like to know more information on ACT planning requirements, see the ACT Planning Portal website.

Cubitt’s have been building Granny Flats and home extensions throughout New South Wales and the Australian Capital Territory for over twenty-five years. Over this time, we have built on all kinds of blocks of land, and have the experience necessary for construction on narrow, sloping or difficult blocks.


We are passionate about providing customers with a stress-free experience, and handle the council approval process for you. Our council planning and drafting teams understand the intricacies of working with different councils, knowing what details to look out for and can plan ahead to ensure a smooth process - avoiding any unnecessary delays or added costs.

Every Cubitt’s customer has a dedicated point of contact, to keep you updated every step of the journey so you can spend less time worrying about the project and more time choosing colour palettes, furnishings and fittings for your new and improved home!

Our team is ready to help answer any questions you may have. Speak with one of Cubitt’s experienced consultants about building a secondary dwelling on your property, by calling 1300 721 150 today.



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About Vince Zinghini

Vince is Cubitt's Director of Planning. With two decades experience in NSW and ACT Council planning and a team of people covering the specific areas in which Cubitt's build, its rare to find a planning scenario we haven't been able to tackle.