Backyard Grannys Granny Flat Design & Approval Guide

 In Granny Flat Designs, Granny Flat FAQs

Planning to build a granny flat? Here’s what you need to know

You’ve taken the first step and decided to build a granny flat, but is your property actually suitable for the construction? There is a lot to consider well before the excavators are brought in and it can be a little overwhelming.

To take the worry and hassle out of all the compliance requirements for building a granny flat, Backyard Grannys have put together this handy guide that outlines in simple terms what you need to know. We’ve also added a section to help you bust the building jargon.

But remember, the experienced team at Backyard Grannys is always available to help you through the process.

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What is a granny flat?

A granny flat is a secondary dwelling that is self-contained either within, attached to or separate from the main dwelling (also known as the principal residence) and satisfies the NSW Affordable Housing State Environment Planning Policy (SEPP). It must be established in conjunction with the principal residence, meaning it doesn’t qualify as a granny flat if it is to be built on a vacant block of land or as part of a subdivision. Those dwellings require different approvals processes.

For approval under the SEPP, the minimum size of your property must be 450 square metres and your property needs to be 12 metres wide. If your property is less than these dimensions, the SEPP doesn’t apply. The granny flat itself can be no larger than 60m² in internal floor space.

Your granny flat must be built at least three metres away from any significant tree trunks (that is the roots of a native tree that is less than five metres tall). Otherwise you will need to make a call to your local council for advice about tree-removal.

On the subject of local councils, there is no need to submit a local development application as long as the granny flat application meets all the SEPP regulations.

Granny Flat Approvals: Rules For Building Backyard Granny Flats

There are a variety of requirements to consider when applying for approval on your pending granny flat build. Key requirements include:

  • Zoning – the property must have residential zoning. These include Zone R1 (General Residential), Zone R2 (Low-Density Residential), Zone R3 (Medium Density Residential), Zone R4 (High-Density Residential), and Zone R5 (Large Lot Residential, although this is via development application only).
  • Setbacks – if the lot is less than 900 square metres, the granny flat must be at least three metres from the rear boundary of the area and 0.9 metres from the side boundaries. If the property is greater than 900 square metres, the build must be at least five metres from the back of the lot and 1.5 metres from the sides. The front setbacks must be the average distance of the setbacks of the nearest two dwellings. There is a minimum 1.8 metres needed between the granny flat and the original house (otherwise a fire-rated wall is needed). There are exceptions for attached granny flats and builds adjoining to laneways.
  • Building height requirements – the maximum height for a compliant granny flat is 8.5 metres, measured as the vertical distance between the existing ground level and the highest point of the new building. Exclusions include flagpoles, antennas, satellite dishes, chimneys, masts and the like. Although IF the height of the secondary dwelling or granny flat, exceeds 3.8 metres then this setback will increase relative to the height of the building as well as the lot size.
  • Landscaping – a minimum of 25% of the property’s landscaping (turf, soil, gardens) must remain. Half of this needs to be behind the main dwelling. This may vary between different sized properties and in the case of attached granny flats.
  • Stormwater drainage – downpipes need to be connected to one of the following; an existing drainage system (the gravity-fed system to the street kerb), an inter-allotment drainage easement (registered system) or an on-site disposal system (a ‘rubble pit’ in the rear yard). This is a requirement for attached and detached granny flats.
  • Outdoor living area – to satisfy the SEPP, granny flats are required to have an outdoor living area that is a minimum of 24m² and must be accessible from the internal living area.

Design and Approval Building Jargon

Unless you’re a seasoned builder like those in the team at Backyard Grannys, you could be forgiven for thinking the construction industry has its own special language. Over the course of planning, designing and constructing your granny flat, new concepts, anagrams and words will find a way into daily conversation.

Below is a list of some of the most common building terms used and what they refer to.

  • Section 10.7 (formerly known as Section 149 Certificate) – also known as zoning certificates, these are legal documents that contain information regarding how a property may be used and any restrictions on development that apply. A section 149 (2) is required when properties are bought and sold.
  • CC – a Construction Certificate must be granted before any building works start, and ensures the proposed construction is compliant with the approved DA and any conditions applied to it. If you have been given the go-ahead to build your granny flat under a CDC, you have already had the CC issued during that process.
  • CDC – a Complying Development Certificate (CDC) is issued by a private certifier rather than your local council and is assessed against the SEPP rather than your local council.
  • OC – an Occupation Certificate document is issued by a building surveyor, which shows that the building is suitable for occupation.
  • Covenant – an agreement that creates an obligation on the owner of a property not to do something.
  • DA – a Development Application refers to the process of approval for a building project where Council assesses the application based on applied community standards, planning and development legislation and Council requirements.
  • The difference between a CDC and DA? A CDC is a streamlined process specifically for buildings that are of low impact to the community and the approval process time is legislated at 10 days. A DA can take more than 120 days, depending on the issues to be considered, and the Council’s application of regulations and requirements. Also, as part of this process, a DA notification period applies. While the CDC is quicker, a DA process will allow scope for consultation and more flexibility in planning.
  • Dial Before You Dig – the essential first step before bringing in the excavator. Dial Before You Dig is a free national referral service designed to assist in preventing damage and disruption to Australia’s vast infrastructure networks which provide essential services we use every day. Just call 1100.
  • Easement – the right held by one person to make use of the land of another, for example land set aside for drainage and sewerage pipes.
  • PPOS – Principle private open space (detached granny flats must have an outdoor entertainment area of at least 24 square metres that’s directly accessible from the living room).
  • Private Certifier – if you need a construction certificate or complying development certificate, you must engage a principal certifying authority (PCA) before work starts on your granny flat. Your certifier will only issue a development certificate if the work complies with the relevant conditions of consent, the approved plans and the legislative requirements.
  • Setback – how far from the front boundary a property can be built.
  • Section 7.11 Developer Contribution (formerly known as Section 94 Council Contribution) – more commonly called development contributions. The NSW Environmental Planning and Assessment Act permits local Councils to charge developers for contributions for public infrastructure that is deemed necessary due to a new development. Examples include the need for additional community facilities, open space such as parks, playgrounds, sporting fields and cycle ways, and roads.
  • Section 50 – applies to water and sewer services within the Hunter Water area of operations. Every new construction requires an investigation to determine the impact of proposed development on existing water and sewage systems and whether new works need to be undertaken to provide water and sewage services. Only by following the five-step development assessment will you be issued a Section 50 Certificate to have services connected.
  • Soil test – a test conducted to determine how a house must be built. Establishes how likely it is that the soil will move, expand and contract with different levels of moisture content.
  • Zoning – the legally permitted and prohibited uses of a piece of land, determining if a lot can be used for commercial, industrial, residential or agricultural purposes. In other words, it decides what can and cannot be built on a lot.


Click here to find out more about building a granny flat with no council approval. If you would like to discuss your granny flat approval get in touch with our friendly staff today by filling in the form below and we can point you in the right direction and ensure you gain approval, first time.

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