Can You Build a Granny Flat on Lot Sizes Less than 450m2?

August 29, 2023

Are you yearning for a little extra living space, or a way to expand an investment but think your property is too small to accommodate it? Think again! The notion that a Granny Flat can't find its place on a property with less than 450m² is a misconception. The truth is, with the right planning team and a thorough understanding of the regulations, you can indeed add a secondary dwelling to your smaller lot. Read this article and note the council areas that allow this via their Local Environmental Planning (LEP) guidelines, a talk to Cubitt's about building a Granny Flat on your less than 450m2 block, today.

Unraveling the Regulations for Blocks Less Than 450m2


Before you dive headfirst into your Granny Flat project, it's important to comprehend the regulatory landscape. There are distinct avenues through which you can seek approval for your secondary dwelling:

1. Complying Development Certificate (CDC)

A secondary dwelling can be approved by lodging a complying development application with Council or a Private Certifier. This is the most preferred way of obtaining approval to build a secondary dwelling as it is the quickest and usually the most straight forward. To receive a CDC, you must comply with the requirements in the in the State Environmental Planning Policy (SEPP) (Housing) 2021. In the SEPP, a minimum lot size of 450m2 and a minimum lot width of 12m is required. A secondary dwelling approved as complying development must also be on land zoned R1, R2, R3 or R4.

2. Development Application (DA) using the SEPP (Housing) 2021

A secondary dwelling may also be approved with a DA using the SEPP (Housing) 2021 and as with all Development Applications in NSW, it must be approved by the Local Council. This application would require the lot size to be a minimum of 450m2. The possible reasons for lodging a DA using the SEPP (Housing) 2021 rather than applying for a CDC may be, the lot is zoned R5, the lot is located within a heritage conservation area or the land is affected by high risk or high hazard flooding. There are other reasons a CDC may not be appropriate and a DA using the SEPP (Housing) 2021 is a better alternative.

3. Development Application (DA) using the Local Environmental Plan (LEP)

Each Local Council has its own LEP and each LEP has different development requirements that need to be addressed when lodging a DA this way. This approval pathway is how we may be able to build a secondary dwelling on a lot less than 450m2.

Which NSW Councils Allow Granny Flats on Less than 450m2 Blocks?

Below is a list of Local Councils that either support or do not support a secondary dwelling on a lot size less than 450m2. If you do not see the Council you need, please contact the Planning Department for more information. *Please note information is up to date September 2023, but subject to change. If in doubt, request a Site Assessment and we'll be armed with all the information you need.


Less than 450m2 allowable* 450m2 or more required
Bayside Blacktown (500m2 min attached, 600m2 min detached)
Blue Mountains Fairfield
Camden Lake Macquarie
Campbelltown Penrith
Central Coast
Port Stephens
Upper Hunter

Can You Build a Granny Flat on Your Block?


Beyond the Minimum Lot Size

While the minimum lot size requirement might seem like a roadblock, it's crucial to recognise that regulations aren't set in stone. Local Councils have the power to grant exceptions and exercise discretion based on various factors. Demonstrating the compatibility of your proposed Granny Flat with the neighborhood, highlighting smart design that maximizes space, and addressing any concerns raised by the Council can all contribute to a successful approval process.

Unlocking Your Property's Potential

The takeaway here is that your property's size doesn't have to limit your aspirations for extra living space. With a thorough grasp of the regulations and a strategic approach, you can create a harmonious coexistence between your secondary dwelling and your smaller lot. Whether it's through a CDC, a tailored DA under SEPP (Housing) 2021, or a well-aligned DA under the Local Environmental Plan, your dream of a granny flat is within reach – yes, even on a lot smaller than 450m²!

Here to Help

Cubitt's have a dedicated planning department ready to work with your Design Consulatent to investigate what is possible on your property.  Just ask.

Need Some Expert Help?

Knowledge is non-negotiable. Our Design Consultant will measure out your site and help you fully understand the possibilities for your block, and be able to discuss in detail your options for a CDC or Development Application. When you’re planning to build, you want assurance that your site is suitable, and that you are not going to be impacted mid-build by unforeseen or surprise costs. We provide a thorough, free, upfront feasibility study for your Granny Flat which gives you an assured green light to build.

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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.