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When you build with GrannyFlow, you receive dedicated, hands-on guidance designed to keep your project on track and free of surprises. At every milestone we are upfront about what needs to happen, what it will cost and how long it will take so you always know exactly where you stand.
Most granny flat projects in Sydney typically range between $140,000 and $220,000, depending on size, design and site conditions.
You are dealing directly with a licensed NSW builder not a lead generation website or third-party referral service.
In 2009, the NSW Government introduced the Affordable Housing State Environmental Planning Policy (SEPP), opening a faster approval pathway for secondary dwellings across the state.
If your property meets the Complying Development Certificate (CDC) criteria, your granny flat can be approved by a private certifier rather than going through a full council development application.
This streamlined pathway has made hundreds of thousands of Sydney properties eligible for granny flat construction.
| Lot Size (m²) | Min. Frontage | Max. Site Coverage | Max. Total Floor Area (house + flat) | Side Setback | Rear Setback | Min. Landscaped Area |
|---|---|---|---|---|---|---|
| 450–600 | 12 m | 50% | 330 m² | 0.9 m | 3 m | 20% |
| 600–900 | 12 m | 50% | 380 m² | 0.9 m | 3 m | 25% |
| 900–1,500 | 15 m | 40% | 430 m² | 1.5 m | 5 m | 35% |
| Over 1,500 | 18 m | 30% | 430 m² | 2.5 m | 10 m | 45% |
A maximum of one granny flat is allowed per lot — two granny flats on a single title is not permitted under the current legislation. A primary residence must already exist on the land (or have passed its own approval stage) before a granny flat application can proceed.
The design must incorporate an outdoor courtyard of no less than 24 m² — at least 4 m in width — in addition to the 60 m² maximum internal living area. This courtyard may overlap with the property’s required setback zones.
On battle-axe lots, the access driveway must be at least 3 m wide to provide adequate entry and exit.
Approval Guide
Discovered that your property falls short on one or more CDC criteria? That doesn’t mean a granny flat is off the table. A Development Application (DA) lodged directly with your local council is the alternative route.
Every council operates under its own Development Control Plan (DCP), so the specific rules and flexibility around secondary dwellings vary from one local government area to the next. Keeping across these differences is critical and it’s something our team does as a matter of routine.
GrannyFlow has navigated council processes across dozens of Sydney LGAs. We stay on top of evolving DCPs so our advice is always current. Our design consultants prepare and lodge every form and supporting document on your behalf, so you don’t have to wade through the paperwork yourself.
The smartest first move — regardless of which pathway applies is a free, no-obligation site assessment. Our assessors arrive with the latest planning tools and mapping software, assess your property’s specifics and recommend the most efficient approval route.
Free site assessments are available within the Sydney metropolitan area. Conditions may apply
Before we visit your site, we strongly recommend gathering three key documents: a Section 10.7 Certificate, a Sewer Diagram and a Title Search. Having these on hand lets us deliver an accurate quote and flag potential issues from the very first meeting.
At GrannyFlow, transparency is non-negotiable. When our assessors arrive at your property for the first time, they’ve already interrogated a range of digital planning and utility tools to identify anything that might affect budget, positioning or approval likelihood. The documents
Also called a Planning Certificate (previously known as a Section 149), this document is a comprehensive snapshot of your property’s planning controls — zoning, restrictions, heritage overlays and more. You may already have a copy from your purchase contract, but if more than six to twelve months have passed, we recommend ordering a fresh one from your council to ensure the information is current.
This plan shows the locations of private drain lines and Sydney Water mains running through or near your lot. It’s usually included in your contract of sale; if not, you can obtain one via the Sydney Water Tap-in portal. Sewer positions can materially affect where a granny flat sits on your land and whether encasement works are required. Our designers are highly experienced at crafting layouts that minimise interference with sewer infrastructure and keep associated costs as low as possible.
What If a Main Sewer Line Runs Through Your Preferred Build Location?
Discovering a Sydney Water main beneath the area where you want to place your granny flat does not rule the project out. There are two practical approaches:
Route the design around the buffer zone. The most cost-effective solution in most cases is to reposition the dwelling so that it falls entirely outside the sewer’s zone of influence. Whether this is achievable depends on the width of the buffer, where the pipe sits on the lot and how much usable space remains once setbacks are accounted for.
Construct within the buffer zone. If avoidance is not feasible, building over the main is still permitted — but because Sydney Water retains legal ownership of the pipe, the affected section must be encased in concrete. The encasement needs to extend the full length of the building that overlaps the zone, plus an additional metre at each end. A granny flat that sits across 6 m of the zone, for example, would require 8 m of encasement in total.
Neither scenario is a dead end. Our design team regularly produces efficient layouts that reduce overlap with the restricted zone to the bare minimum, keeping encasement requirements — and the associated costs — as low as practically possible.
Your Certificate of Title reveals legal ownership, easements (rights held by other parties to use portions of your land) and covenants (conditions attached to the title that may govern what can be built). Understanding these before design begins prevents costly surprises later. Title searches are available through the NSW Land Registry Services or various online providers.
Registered Owners. The certificate confirms exactly who is legally entitled to the property. Verifying ownership upfront ensures that any granny flat approval and construction proceeds with the correct parties on record.
Easements. An easement is a registered right that allows a third party — such as a utility provider or a neighbouring property owner — to access or make use of a defined strip of your land. The most frequently encountered types are right-of-carriageway easements and stormwater drainage easements. Any building work that encroaches on an easement requires formal consent from the relevant authority before it can proceed, so identifying these early is essential to setting realistic design boundaries.
Covenants. A covenant is a binding condition attached to the title that places specific obligations on the property owner. These obligations vary widely — some regulate the external appearance of buildings on the lot (for instance, restricting facade materials or colour schemes), while others govern drainage infrastructure or the types of structures permitted. If a covenant limits what you want to achieve, it can in many cases be modified or discharged, either with the written agreement of the party who benefits from it or through a formal application to the Land and Environment Court in NSW.
Title records across New South Wales are held by NSW Land Registry Services. A copy of the Certificate of Title is normally included in the Contract of Sale. If you do not have access to it, a duplicate can be purchased through any of the licensed online conveyancing search platforms.
Not at all. We understand that the lead-up to a build can feel overwhelming particularly if paperwork isn’t your thing. Our client services team can source every document listed above on your behalf. Just mention it during our initial conversation and we’ll handle the rest while you focus on envisioning your new space.
Cost
There is no single price tag for a granny flat. The final cost depends on design complexity, finishes, and site conditions. Most granny flat projects in Sydney range between:
The best way to get an accurate estimate is through a free site assessment.
Process Overview
From the moment you first contact us through to key handover, a dedicated team member guides you through every stage of the build.
We offer three participation tiers:
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