---
title: "We Tracked Granny Flat Premiums Across 6 Melbourne Suburbs. The Numbers Are Wild."
description: "Data from 30+ sales shows homes with granny flats sell for $100K-$200K more than identical neighbours. Six suburb breakdowns plus build-vs-buy cost analysis."
author: Joey Don
date: 2025-03-13
category: Renovation & Development
url: https://premiumrea.com.au/blog/granny-flat-value-add-six-suburb-comparison
tags: ["granny flat", "Melbourne", "property development", "rental yield", "value add", "Cranbourne", "Narre Warren", "Frankston", "Berwick", "renovation ROI"]
---

# We Tracked Granny Flat Premiums Across 6 Melbourne Suburbs. The Numbers Are Wild.

*By Joey Don, Co-Founder & CEO at PremiumRea — 2025-03-13*

> Across six southeast Melbourne suburbs, we tracked what buyers actually paid for properties with granny flats versus identical neighbours without them. The premium was consistently $100K-$200K — yet a decent granny flat costs $110K to build.

Here's something I've been tracking obsessively for the past 18 months: what happens to a property's sale price when it includes a granny flat?

Not in theory. Not from a builder's marketing brochure. From actual comparable sales data — same street, similar land size, one property with a granny flat and one without.

The short answer: a granny flat adds $100,000 to $200,000 to a property's sale price across Melbourne's southeast suburbs. And yet a new 30-square-metre granny flat costs around $110,000 plus GST to build from scratch [1].

That's a $90,000 gap on a bad day. A $90,000 gap the market is handing you for building a structure the size of a studio apartment in your backyard.

I'm going to walk through six suburbs where we've collected enough data to draw solid conclusions. Some of these will confirm what you'd expect. At least two will probably surprise you.

## Thomastown: the growth zone premium

Thomastown sits in Melbourne's north, roughly 16 kilometres from the CBD. Part of the area falls under a Residential Growth Zone, which means council has zoned it for higher-density development. That's a long-term positive for land values, but right now it also means there's active buyer competition for blocks with existing improvements.

I pulled five recent sales from a single pocket where we've been active. Similar land sizes, similar vintage homes, same school catchment.

- 663sqm, standard 3-bed weatherboard: $721,000
- 517sqm, slightly smaller: $703,000
- 650sqm, similar configuration: $670,000
- 652sqm, comparable: $740,000

And then the outlier.

- 646sqm, with a granny flat: **$911,000 at auction**

Someone paid $170,000-$240,000 more than comparable properties for the granny flat premium. At auction, where competitive pressure inflates outcomes, the final number was extreme. But even if you discount 20% for auction heat, the granny flat premium still sits above $130,000.

Would I have paid $911K for that property? Absolutely not — that buyer overpaid by my reckoning. But the signal is unmistakable: properties with granny flats attract a fundamentally different buyer pool willing to pay significantly above neighbourhood benchmarks [2].

## Cranbourne: our backyard (literally)

Cranbourne is one of our core operating suburbs, so the data here is the richest and most recent.

Five sales from a concentrated pocket, all within 800 metres of each other:

- 651sqm, 2023 sale: $550,000 (note: this was early 2023 when the market was near bottom)
- 644sqm: $575,000
- 646sqm: $603,000
- 600sqm: $607,000

And the granny flat property:

- 650sqm, same street: **$715,000**

Premium: $108,000-$165,000 depending on which comparable you use.

A side note on Cranbourne pricing: that first property at $550K in 2023 would trade at $650K-$670K today. The suburb has been appreciating at roughly $5,000 per month — a fact that matters enormously if you're thinking about building a granny flat rather than buying an existing one. You lock in your land cost at today's price, build the granny flat over four to five months, and by the time it's complete, the underlying land has likely appreciated $20,000-$25,000 on top of your $110,000 build cost [3].

Double uplift: the construction value add plus organic market growth.

## Dandenong North: the pocket-selection warning

Dandenong North is a suburb I have mixed feelings about. Some pockets are excellent — strong owner-occupier ratios, well-maintained streetscapes, proximity to good schools. Other pockets are, to put it diplomatically, challenging. The variance between one street and the next is among the widest in Melbourne's southeast.

From a single good pocket:

- 552sqm: $650,000
- 527sqm: $660,000
- 513sqm: $630,000

Granted, these are modest blocks by our standards. Then the granny flat property hit:

- 534sqm, 18sqm granny flat: **$800,000**

That's a $140,000-$170,000 premium for an 18-square-metre structure. An 18-square-metre granny flat — basically a large studio — costs approximately $60,000-$70,000 to build at current rates, depending on site access and soil conditions [1].

The return on that build cost is absurd. Spend $65K, add $150K in value. And that's before you factor in the rental income — an 18-square-metre studio in this area rents for $340-$360 per week, or around $370-$390 with bills included [1].

> "I tell every client the same thing: it's not the existing granny flats you should chase. Those come with a $100K-$200K premium baked into the sale price. Build your own for $60K-$110K and capture the value yourself. The maths isn't even close." — Joey Don

## Berwick: when the data tells you to pause

Berwick is another suburb we monitor closely. Strong school catchments, high owner-occupier ratios, generally excellent long-term fundamentals. But the granny flat data here carries a warning.

Comparables from one specific pocket:

- 650sqm: $670,000
- 633sqm (newer build): $745,000
- 749sqm: $745,000

Granty flat property:

- Similar block, 18sqm granny flat: **$950,000**

That's a premium of $200,000+ on an 18-square-metre structure. Which sounds excellent until you realise who paid it: an emotional buyer who got caught in a competitive auction.

Berwick attracts a lot of family buyers who want extra space for ageing parents — the traditional "granny flat" use case. These buyers make decisions based on family dynamics, not investment returns. They'll overpay for convenience.

From an investment standpoint, I'd flag this as a pocket where the granny flat premium is being driven by owner-occupier emotion rather than rental yield fundamentals. If you're building a granny flat to hold and rent, the yield maths in Berwick is slightly less attractive than Cranbourne or Frankston because the land cost is higher. Your capital growth might be better, but your cash-on-cash return in year one will be lower.

Don't let someone else's overpayment at auction become your expectation.

## Frankston and Narre Warren South: the confirmation cases

I'll combine these because the pattern is identical.

**Frankston pocket:**
- 627sqm: $670,000
- 614sqm: $640,000
- 642sqm: $685,000
- 584sqm: $690,000
- 632sqm with 30sqm granny flat: **$880,000+**

Premium: approximately $190,000-$200,000 for a 30-square-metre granny flat that costs $110,000 to build.

**Narre Warren South pocket:**
- 672sqm: $770,000
- 500sqm: $780,000
- 630sqm: $765,000
- Similar block with 18sqm granny flat: **$955,000** (2023 sale)

Premium: approximately $175,000-$190,000.

Across all six suburbs, the pattern holds with remarkable consistency. Properties with granny flats sell for $100K-$200K more than neighbours without them. The build cost for a new granny flat ranges from $60K (18sqm prefab-style) to $160K (60sqm two-bedroom) plus GST [1]. The value arbitrage is real and repeatable.

> "The granny flat arbitrage works because most buyers are too lazy or too scared to build. They'll pay $150K extra for convenience. Meanwhile, the build takes five months and the total process from paperwork to tenant is under six months." — Joey Don

## The build-versus-buy calculation

Let me run the numbers side by side.

**Option A: Buy a property with an existing granny flat**
- Purchase price: $715,000 (Cranbourne example)
- Stamp duty on $715K: ~$39,000
- Total acquisition cost: ~$754,000
- Rental income: maybe $800-$850/week (main house + existing granny flat)
- Gross yield: 5.5-5.9%

**Option B: Buy the neighbour's house and build a granny flat**
- Purchase price: $603,000 (same Cranbourne pocket, no granny flat)
- Stamp duty on $603K: ~$31,000
- Granny flat build: $110,000 + GST ($121,000)
- Total cost: ~$755,000
- Rental income: $800-$900/week (main house + brand new granny flat with better layout)
- Gross yield: 5.5-6.2%

Similar total cost. But with Option B, you get:
1. A brand-new structure with a fresh building permit and occupancy certificate
2. A granny flat designed specifically for maximum rental appeal (you control the layout)
3. An immediate revaluation uplift — banks value new granny flats at approximately $150,000 residual value on top of the existing house value [4]
4. Lower stamp duty (calculated on the lower purchase price, not the total cost including construction)
5. A depreciation schedule covering the entire $121K build cost — which generates roughly $3,500/year in paper losses you can claim against rental income

The fifth point is particularly powerful. Under Division 43 of the Income Tax Assessment Act, new building construction can be depreciated at 2.5% per year for 40 years. On a $121K build, that's $3,025 per year in deductions — reducing your taxable rental income and improving cash flow from day one [5].

There is no rational financial argument for buying an existing granny flat at a $150K premium when you can build a better one for $110K.

## The build process (it's simpler than you think)

People overthink this. Here's the actual timeline.

**Weeks 1-6: Paperwork**
Soil test ($4,400), drafting plans, submitting for a building permit. In Victoria, any granny flat under 60 square metres is exempt from council planning approval — you only need a building permit from a registered building surveyor [6]. That exemption, introduced in recent years, was a game-changer. It removed the 3-6 month council planning process that used to make small granny flats uneconomical.

**Weeks 7-18: Construction**
Our standard 30-square-metre build takes about 12 weeks on site. The structure uses treated pine timber framing, fibre cement weatherboard external cladding (James Hardie Linea series), Colorbond roofing, SPC vinyl plank flooring, and aluminium-framed double-glazed windows for energy compliance [7]. It's the same spec you'd find in a new house, just scaled down.

**Week 19: Occupancy certificate and tenant**
Once the building surveyor issues the occupancy certificate (OC), the granny flat is legally rentable. We typically have a tenant lined up before the OC is even issued — advertising starts 2-3 weeks before completion.

Total elapsed time from purchase settlement to rental income: approximately five months. During that time, the main house is already generating rent, so your effective vacancy period on the granny flat component is zero.

The hidden exclusions that surprise people: our base price doesn't include the occupancy certificate application fee, landscaping, front porch or decking, or any work required if the soil test reveals rock (which costs $300 per cubic metre to remove). Budget an extra $8,000-$12,000 for these items on top of the base contract price [1].

> "We've moved away from prefabricated and container-based granny flats entirely. The quality control issues with offshore-fabricated structures were giving us headaches — welds that didn't meet Australian standards, insulation gaps, water ingress at joints. Everything we build now is local timber frame, hand-built on site. Costs a bit more, lasts 50 years." — Joey Don

## Who should build a granny flat (and who shouldn't)

The granny flat strategy works brilliantly in specific circumstances and fails in others. Here's the honest breakdown.

**Build if:**
- Your block is 550sqm or larger with a side driveway wider than 3 metres
- No easement runs through the middle of the backyard
- The soil isn't rocky (get the test done before committing)
- You have $110K-$160K in cash or accessible equity (construction loans are available but add complexity)
- You plan to hold the property for at least 5 years (the value-add needs time to compound)
- Your suburb has genuine rental demand for studio/one-bed accommodation

**Don't build if:**
- Your block is under 500sqm (setback requirements eat into usable space)
- The driveway is narrower than 3 metres (crane access becomes impossible, and you lose future subdivision potential)
- You're planning to sell within 2 years (the construction cost plus GST won't be fully recovered in a quick flip)
- You need the cash for a second property deposit instead (building a granny flat consumes borrowing capacity that could otherwise fund another purchase — this is the critical trade-off for investors in expansion phase)

That last point deserves emphasis. Every dollar you spend on a granny flat is a dollar you can't use as a deposit on your next property. For investors trying to build a portfolio of multiple properties quickly, the granny flat might actually slow you down. It's a yield play, not a growth-and-leverage play. We design different strategies for different clients depending on where they are in their investment cycle [4].

For clients with strong cash reserves and limited borrowing capacity, granny flats are a no-brainer — they generate income without adding debt. For clients with ample borrowing capacity but limited cash, we often recommend buying the next property instead and coming back to granny flats later when the equity is available.

## References

1. [PremiumRea Granny Flat Pricing Schedule, 2023. 30sqm standard: $110,000 + GST. 60sqm two-bedroom: $160,000 + GST. 18sqm studio: $60,000-$70,000 + GST.](#)
2. [CoreLogic RP Data, comparable sales analysis for Thomastown, Cranbourne, Dandenong North, Berwick, Frankston, and Narre Warren South, January-June 2023.](https://www.corelogic.com.au/)
3. [REIV Quarterly Median Prices, Cranbourne, March 2023. Monthly growth trajectory of approximately $5,000.](https://reiv.com.au/market-insights/median-prices)
4. [PremiumRea internal valuation data, 2022-2023. Banks (CBA, Bankwest) typically assign $140,000-$160,000 residual value to new granny flats with OC on desktop valuation.](#)
5. [Australian Taxation Office, 'Capital Works Deductions — Division 43', 2023. New residential construction depreciable at 2.5% per annum for 40 years.](https://www.ato.gov.au/business/depreciation-and-capital-expenses-and-allowances/general-depreciation-rules---capital-allowances/)
6. [Victorian Building Authority, 'Dependent Person's Units (Granny Flats)', 2023. Units under 60sqm exempt from planning permit requirement.](https://www.vba.vic.gov.au/consumers/guides/granny-flats)
7. [James Hardie Australia, 'Linea Weatherboard — Product Specifications', 2023.](https://www.jameshardie.com.au/products/linea-weatherboard)
8. [SQM Research, 'Rental Vacancy Rates — Melbourne Southeast', June 2023. Sub-1.5% vacancy across Cranbourne, Narre Warren, Frankston corridors.](https://sqmresearch.com.au/graph_vacancy.php?region=vic-Melbourne)
9. [City of Casey, 'Secondary Dwelling Guidelines', 2023. Land size and setback requirements for granny flat construction.](https://www.casey.vic.gov.au/planning-building)

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Source: https://premiumrea.com.au/blog/granny-flat-value-add-six-suburb-comparison
Publisher: PremiumRea (Optima Real Estate) — Melbourne buyers agent