The Australian Granny Flat Guides & Costs Hub
Start with what it costs in your state, then the approval path, then a floor plan. This page is the index for those guides.
Which Guide Should You Start With?
Four research areas covering the questions homeowners ask us most.
Costs & Finance
Construction & Materials
Steel versus timber frames, roofing choices and slab requirements explained in plain English.
Explore constructionRegulations
State rules, setbacks and permit guides so you know what your council will and will not approve.
Explore regulationsRules by state
Compare size limits, approval pathways and rental rules for every Australian state in one table.
Open state hubDesigns & Ideas
Floor plans, interior styling and space-saving layouts for compact secondary dwellings.
Explore designsWhat Should You Know Before You Budget?
The details that quietly decide whether your project comes in on budget.
Kit price is not the finished price
Multiply the kit price by roughly 2.5 to 3 to reach your real move-in cost. A $30,000 kit usually finishes at $75,000 to $90,000 once trades, slab and fit-out are done.
Stay under the approval threshold
In NSW, staying under 60 sqm internal is how a lot of CDC jobs stay on the fast path. Victoria's small second dwelling rules also cluster around 60 sqm. Western Australia's R-Codes sit nearer 70. Over those caps and you are usually in a slower permit. Confirm on the state planning page, not a brochure.
The silent budget killer
Find your sewer tie point before you pick a spot. Digging under a driveway or pumping uphill can triple your plumbing costs.
Granny Flat Guides FAQ
Short answers before you dive into the longer articles.
How much does a granny flat cost in Australia in 2026?
Most finished projects land between about $90,000 and $220,000 all-in, depending on size, site works and finish level. Kit shells look cheaper on paper; slab, trades, council fees and connection costs usually close the gap. Use the cost calculator for a first pass, then confirm with local quotes.
Do I need council approval for a granny flat?
Almost always yes, unless you are installing a relocatable unit that your state treats as a caravan or similar temporary structure. New South Wales often uses CDC for complying designs; Victoria and Queensland use different labels for the same idea. Check the state rules hub for your lot before you pay a deposit.
Where should I start if I am still researching?
Start with a realistic budget and your state size and setback caps, then pick a design that fits both. After that, compare prefab, kit and custom paths on the supplier hub. Jumping to floor plans first is how people fall for a layout their council will not approve.
Not Sure What Your Build Will Really Cost?
Use our free on-page calculator to estimate preliminaries, site costs, the build and finishes before you read another guide or call a supplier.
Open the cost calculatorPlanning tools: approval wizard, setback checker and build comparator.
Latest Guides
Our most recent articles on costs, construction, regulations and design.
Augusta Margaret River Lifts Some Granny Flat Limits to 120 sqm
Augusta Margaret River's new planning scheme increases the maximum size of ancillary dwellings on rural and rural residential properties from…
Read the guideHow to Compare Granny Flat Quotes Without Missing Costs
Compare a granny flat quote by pricing the same finished project, including work left outside the builder's offer. Two totals…
Read the guideGranny Flat Depreciation Schedule Australia: What to Check
A granny flat depreciation schedule in Australia records potential deductions for eligible capital works and depreciating assets. It does not…
Read the guideCan You Subdivide a Granny Flat in Australia? State Rules
You cannot assume a granny flat can be subdivided or sold on a separate title. Approval for a second dwelling…
Read the guideWA Granny Flat Rules 2026: Ancillary Dwelling Approvals
Updated 13 September 2026. Western Australian planning updates have clarified the WA granny flat rules 2026 under the amended Residential…
Read the guideSmall Second Dwelling Permit Victoria: Correction to Our Data Report
Small second dwelling permit Victoria guidance distinguishes planning permission from building approval: a building permit is still required. Our earlier…
Read the guide
