Home › Guides › Prefab and modular granny flats in NSW
Prefab and modular granny flats in NSW: what they cost and what to check
A prefab granny flat or a modular granny flat is made in a factory and finished on your block, but the words do not name one product, and NSW's planning and local government Acts do not define "prefabricated home". What counts is how the unit is built, what the price covers and which approval applies. Here is how prefab, modular, expandable and built-on-site granny flats compare in 2026, with the published prices and estimates we read on 3 November 2026, and what to ask before you pay.
Prefab, modular, expandable or built on site: what is the difference?
Sellers use these words loosely: one NSW comparison site we read on 3 November 2026 treats "prefab" and "modular" as near-synonyms. The main NSW Acts do not use "prefabricated home" as a category: the Department of Planning, Housing and Infrastructure notes that it is not a term defined or used in the Local Government Act 1993, in the Environmental Planning and Assessment Act 1979 or in the regulations under either. So ask what a seller means by "prefab" or "modular" for the unit in front of you.
| Type | How it is made and delivered | Still done on your block |
|---|---|---|
| Built on site | A builder frames and finishes the granny flat on your block | Everything, from the slab to the fit-out: one Sydney builder quotes twelve to sixteen weeks from slab pour to handover |
| Prefab or modular | Built in a factory in one or more sections that travel by truck; how much is fitted out inside varies, so ask | Footings, crane placement, joining the sections, connections and finishing |
| Expandable | Built and fitted out in a factory, travels folded and expands on site; ours travels 2.2 m wide | Footings, crane placement, expanding the unit, fitting the seals and small fittings that travel inside it, connections |
An expandable granny flat is one kind of prefab: a steel-framed unit, finished inside at the factory, that expands on your block. Our Yard 37 expands to 5.9 × 6.3 m, and two of them travel end to end in one 40 ft High Cube shipping container. Our Yard 57 expands to 9.0 × 6.3 m and fills a 40 ft High Cube container on its own. They are not converted shipping containers, and they have no wheels. Our guide to expandable granny flats in NSW explains what the rules ask of one.
What does a prefab, modular, expandable or built-on-site granny flat cost in NSW?
Published prices do not cover the same things, so they cannot be compared line against line. Here are the prices and estimates we read on 3 November 2026:
| Offer | Price shown | What it covers, as published |
|---|---|---|
| Built on site by a Sydney builder, 40 m², one bedroom | From $140,000 | Turnkey, GST included, with statutory Home Building Compensation cover; service connections priced upfront |
| Same builder, 50 m², two bedrooms | From $175,000 | As above |
| Same builder, 60 m², two bedrooms | From $210,000 | As above; the builder states an engineered-footing premium of $12,000 to $28,000 on many Western Sydney sites, shown in the fixed-price contract |
| Expandable unit, 30 ft model | From $124,000 | Fit-out, kitchen and bathroom, structural engineer's report, certifications and drawings, council application and council fees; footings, site preparation, delivery, crane and service connections are extra. The page does not say whether GST is included |
| Prefab or modular unit: indicative estimate by a comparison site, not a seller's price | Factory price $85,000 to $140,000; delivered and connected $140,000 to $230,000 | The factory price is for the building only. Transport ($3,000 to $10,000), crane and traffic control ($3,000 to $12,000), footings or piers ($8,000 to $25,000), site works and connections ($15,000 to $45,000), and approvals and certification ($4,000 to $9,000) are estimated on top |
Two things stand out. A factory price is the price of a building, not of a granny flat you can live in: delivery, crane, footings, connections and approvals come on top, and they depend on your block. And a turnkey price can already include them. Compare totals for the same items: the unit, delivery and crane, approval fees, footings, connections, GST and council contributions.
Our turnkey prices, in Standard finish on a standard metro Sydney block, GST included: from AUD 137,000 for the Yard 37 (two bedrooms in 35.2 m² of floor area) and from AUD 172,000 for the Yard 57 (two bedrooms and a separate living room in about 54.3 m²). Each covers the unit delivered, the GST and import charges paid at the border, the approval fees and the site works by a licensed NSW builder. Council contributions are extra. Our guide to granny flat costs in Sydney shows each part.
Which approval applies to a prefab or modular granny flat in NSW?
A granny flat made in a factory still has to be approved. In NSW it is a secondary dwelling, and it follows one of three pathways:
- Complying development: a complying development certificate (CDC) from your council or a registered certifier, when every standard of Schedule 1 of the State Environmental Planning Policy (Housing) 2021 is met, including a lot of at least 450 m² and, in a residential zone, no more than 60 m² of floor area.
- Development application: lodged with your council when complying development is not available.
- Manufactured home: council approval to install it under section 68 of the Local Government Act 1993, with development consent where the local planning rules require it. A manufactured home is a self-contained dwelling, with a kitchen, bathroom, bedroom, living area, toilet and laundry facilities, made of one or more finished major sections.
Which one applies depends on how the home is made and delivered, and your council or certifier decides. On the building pathway, you need a BASIX certificate and a principal certifier who inspects the work and issues the occupation certificate. On the manufactured home pathway, there is no BASIX certificate, no principal certifier and no occupation certificate: the council relies on a structural engineer's certificate and compliance plates on the home.
NSW passed the Building (Approvals and Practitioners) Act 2026 on 4 August 2026, which will remove the term "manufactured home" and create a certification pathway for prefabricated building work. Most of it has not commenced, so the existing approval processes still apply. Our guide to granny flat rules in NSW sets out each standard.
Who installs it, and who is responsible?
In NSW, building a prefabricated secondary dwelling such as a granny flat needs a separate building licence: the licence for prefabricated metal-framed additions does not cover it (NSW Government, prefabricated additions and structures). Electrical, plumbing and drainage work needs its own licence, whatever the cost. Residential building work over $20,000 must be covered by Home Building Compensation insurance, the builder cannot ask for a deposit or any other payment until the cover is in place, and the deposit is capped at 10% of the contract price. Check the certificate with the insurer before you pay (NSW Government, contracts for residential building work).
Ask whether the contract is for the unit only, or for the unit installed, and who answers for the finished dwelling. A seller who delivers the unit does not, by that alone, build the footings or make the connections: someone with the right licences has to.
Where our units fit: the Yard 37 and the Yard 57
Our units are expandable granny flats, made in a factory and finished inside before they ship. As currently specified, with 2.26 m ceilings and no laundry, they cannot be approved in NSW: the National Construction Code asks for 2.4 m in habitable rooms and for clothes washing facilities, and a manufactured home must include laundry facilities. We are specifying an Australian version with 2.4 m ceilings, a laundry and a cooktop. Nothing is payable to us until that version is confirmed and your council or certifier confirms in writing that it can be approved on your block.
Both stay under the 60 m² limit for complying development: the Yard 37 has 35.2 m² of floor area (37.2 m² overall), and the Yard 57 about 54.3 m² (56.7 m² overall). Allow four to six months from order to delivery for a first order of a model: three to six weeks of approvals, five to seven weeks of production, then shipping, customs and delivery, with the approval for your block first and the licensed NSW builder's site works after.
Questions to ask any prefab or modular seller before you pay
- Which approval pathway applies to my block, and has my council or certifier confirmed it in writing?
- Is the price for the unit alone, or for the unit delivered, installed and connected? Which of delivery, crane, footings, connections, approval fees, GST and council contributions are in it?
- Is the contract for the unit only, or for the unit installed, and who is responsible for the finished dwelling?
- What is the height inside each habitable room, from the finished floor to the ceiling, and where are the laundry facilities?
- For a manufactured home: which practising structural engineer certifies the design, and will the home carry compliance plates?
- Who builds the footings, sets the unit in place and connects it: a licensed NSW builder, with Home Building Compensation cover in place before any deposit?
- Which evidence shows that the materials and products meet the NCC: a CodeMark certificate, a Certificate of Accreditation, a certificate from a certification body, a report from an accredited testing laboratory, an engineer's certificate or other documents?
- If the unit is made overseas: asbestos test reports from an accredited laboratory on samples from my shipment, electrical approvals recognised in NSW and Lead Free WaterMark certificates. Our guide to importing a granny flat from China explains each one.
- When does the clock start, and how long do approvals, production, delivery and the site works each take?
Frequently asked questions
Is a prefab granny flat the same as a modular granny flat?
Not as a matter of law: the main NSW Acts do not define "prefabricated home", and sellers use both words loosely. What decides the approval is how the home is made and delivered: finished major sections, which can make it a manufactured home, or loose parts assembled on site, which is treated as a building. Ask the seller which one it is.
Does a prefab granny flat need council approval in NSW?
Yes. It is approved as complying development (a CDC) if every standard is met, through a development application, or, for a manufactured home, through council approval to install it under section 68 of the Local Government Act, with development consent where the local rules require it. Your council or certifier decides which applies to your block.
Is a prefab granny flat cheaper than building on site?
Compare totals, not factory prices. The prices we read on 3 November 2026 do not cover the same things: a Sydney builder's turnkey price from $175,000 for 50 m² includes connections and Home Building Compensation cover, while a comparison site puts a prefab unit's factory price, for the building alone, at $85,000 to $140,000 and the delivered and connected total at $140,000 to $230,000. The total for a prefab unit depends on delivery, crane, footings, connections and approvals on your block.
How long does a prefab granny flat take?
It depends on the unit and the approval. For ours, allow four to six months from order to delivery for a first order of a model, then the builder's site works. One Sydney builder quotes twelve to sixteen weeks from slab pour to handover for a granny flat built on site.
Do I need a BASIX certificate for a prefab granny flat?
BASIX applies to new homes, so a granny flat approved as a building needs one. A manufactured home does not need a BASIX certificate.
Can I buy a Yard 37 or a Yard 57 now?
You can ask for a written quote now. Nothing is payable to us until the Australian version, with 2.4 m ceilings, a laundry and a cooktop, is confirmed and your council or certifier confirms in writing that it can be approved on your block.
General information, based on official sources and published prices read on 3 November 2026. It does not replace your written quote, or advice from your certifier, your council or a lawyer. Prices and rules change: check the current version before you commit.