A granny flat — also called a secondary dwelling — is a self-contained living space built on the same lot as an existing property. For property investors, granny flats are one of the most cost-effective ways to increase rental yield without buying a second property.
What Are the Benefits of a Granny Flat for Investors?
- Immediate rental yield boost: Adding a granny flat to a house can increase total gross yield by 2% to 4% per annum
- Low cost relative to a second property: A basic granny flat costs $80,000 to $180,000 to build, versus $500,000+ for a second investment property
- No stamp duty: Building on existing land has no stamp duty cost
- Depreciation: New builds attract full Division 40 and Division 43 depreciation deductions
What Are the Planning Rules for Granny Flats?
Rules vary significantly by state and local council. Key considerations include:
| State | Key Rules (General) |
|---|---|
| NSW | Fast-tracked complying development approval if lot is 450sqm+. Max 60sqm internal. Must be on same title as main dwelling. |
| VIC | Requires planning permit from local council. Lot size, setback and height rules vary by zone. No state-wide fast-track as at 2026. |
| QLD | Secondary dwellings permitted in most residential zones. Max 80sqm. Subject to council-specific rules. |
| WA | Permitted in R30 and above zones. Requirements vary by council. |
How Much Rent Can a Granny Flat Generate?
In Melbourne’s inner-north, a well-positioned granny flat commands $350 to $500 per week in rent (SQM Research, 2026). In Sydney’s inner west, $450 to $650 per week is achievable. Over a full year, this equates to $18,200 to $33,800 in additional rental income.
GeeVee Verdict
Granny flats are one of the highest-ROI improvements available to property investors, particularly in NSW where the fast-track approvals process makes construction straightforward. In Victoria, the planning process is more complex but still achievable. Always check with your local council before buying a property specifically to add a granny flat — the planning rules can make or break the strategy.
Frequently Asked Questions
Can I rent out the main house and the granny flat to separate tenants?
Yes. Both the main dwelling and the granny flat can be rented to separate tenants on separate lease agreements. You manage two tenancies but collect two income streams.
Does a granny flat add value to my property?
Generally yes, but not dollar-for-dollar. A $120,000 granny flat typically adds $80,000 to $150,000 in assessed property value depending on location and rental demand. The primary return is the yield improvement during the holding period.
Can I subdivide the granny flat from the main property?
In most states, you cannot separately sell or subdivide a granny flat — it must remain on the same title as the main dwelling. Some states have strata subdivision options for dual occupancies, but this is a more complex and costly process.
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