---
title: "We Added a Granny Flat to a $700K Cranbourne House. Now It Pulls $790 a Week."
description: "Real case study: 700sqm Cranbourne property, $700K purchase, $100K granny flat build, $470 + $320 = $790/week total rent. 5.1% gross yield on $800K total cost. Full numbers inside."
author: Yan Zhu
date: 2024-03-07
category: Renovation & Development
url: https://premiumrea.com.au/blog/cranbourne-granny-flat-700sqm-790-week-case-study
tags: ["granny flat", "Cranbourne", "dual income", "cash flow", "value add", "Melbourne southeast", "rental yield"]
---

# We Added a Granny Flat to a $700K Cranbourne House. Now It Pulls $790 a Week.

*By Yan Zhu, Co-Founder & Chief Data Officer at PremiumRea — 2024-03-07*

> Everyone tells you Cranbourne is a rough area. Too much crime. Too far from the city. Too working class. I hear it all the time. And every single time, I smile, because the people saying it are the same people who cannot work out why their inner-city apartment has gone backwards over ten years.

Everyone tells you Cranbourne is a rough area. Too much crime. Too far from the city. Too working class. I hear it all the time. And every single time, I smile, because the people saying it are the same people who cannot work out why their inner-city apartment has gone backwards over ten years.

Let me put something on the table. An $800,000 house pulling $790 a week in rent. Sitting on 700-plus square metres of land where the land value makes up over 80 per cent of the total price. That is not a hypothetical. That is a deal our team closed recently. And I want to walk you through every single number so you can see exactly how we turned an average-looking property into a serious income generator [1].

Before I get into the specifics, a quick note on my background. I trained as an actuary. I think in probabilities, not feelings. When I evaluate an investment suburb, I do not care whether it looks pretty or whether my friends would want to live there. I care about three things: affordability ratios, population growth trends, and land scarcity. Cranbourne ticks all three boxes, and the data is not even close.

## Why Cranbourne Keeps Showing Up in Our Portfolio

Cranbourne sits in Melbourne's far southeast corridor. It is one of only two suburbs in the region with an activity zone designation, which means state government has earmarked it for ongoing infrastructure and commercial investment. There is a major shopping centre within walking distance of most residential streets—not a strip of dodgy takeaway shops, but a genuine retail and services hub that anchors employment and foot traffic [2].

The median house price in the area sits around $680,000. That sounds like a lot until you look at family incomes. The median household income in Cranbourne is approximately $117,000 per year. Divide the house price by the income and you get an affordability ratio of about 5.8 times. That is extremely affordable by Australian standards—Melbourne's average sits above 9 times. Sydney is closer to 13 [3].

This affordability is the engine behind the suburb's population growth. Young families aged 30 to 45, the demographic with the highest earning trajectory, are flooding into Cranbourne at roughly 6 per cent annual population growth. That is well above the Victorian state average of around 1.9 per cent [4]. These are not retirees downsizing. These are dual-income households with children who need three-bedroom houses and cannot afford established eastern suburbs. They are teachers, tradespeople, nurses, mid-career professionals. The kind of people who pay rent on time because they have too much to lose if they do not.

Owner-occupier rates remain high. Unit and apartment stock is almost non-existent. That means when you own a house on land in Cranbourne, you are competing in a market segment with genuine scarcity—you cannot build apartments on these residential blocks to flood supply. Compare that to suburbs like Point Cook or Craigieburn where new estates pump out hundreds of identical dwellings every quarter, diluting demand and capping rent growth.

Yes, crime statistics are above the Melbourne median. I will not pretend otherwise. But we are talking about investment, not lifestyle. The question is not whether you want to live there. The question is whether tenants want to live there, and whether the numbers work. The vacancy rate in Cranbourne has been below 1.5 per cent for the past eighteen months [5]. That answers the tenant demand question definitively.

I always tell my clients: you are not buying a home. You are buying a business that happens to be made of bricks. And the business fundamentals in Cranbourne are among the strongest in Victoria right now.

## The Property: What We Bought and Why

The house is a three-bedroom, one-bathroom, single-living-area home. The most standard, most boring floor plan you can imagine. Weatherboard cladding. Original kitchen. Carpet that has seen better decades. That is exactly what we wanted. Boring houses on big blocks are the highest-returning asset class in Australian residential property, and nobody wants to hear that because it is not exciting.

The block: 700-plus square metres. Flat. Square frontage. Wide street access. No slope. No flood overlay. No bushfire zone. No high-voltage powerlines. No easement cutting through the backyard. We checked every single one of these before making an offer. Our team physically walks each property and inspects for drainage issues, proximity to industrial zones, and council overlays that might restrict future development. This due diligence takes half a day per property. Most buyers skip it entirely [6].

Our offer price was $700,000. At that price, you are essentially buying land and getting the house for free. The land value alone—based on comparable vacant lot sales in the area—was conservatively $550,000 to $600,000. That means the dwelling sitting on it was valued at $100,000 to $150,000 at most. A $150,000 house generating $470 per week in rent is not a bad deal by itself.

The existing dwelling returns $470 per week in rent, which translates to a gross yield of about 3.5 per cent on the total purchase price. Nothing special. If we stopped there, this would just be another average Melbourne investment. The kind of property that ticks along unremarkably for twenty years while you wonder whether it was worth the effort.

But we did not stop there.

The backyard had more than enough room—well over the 550 square metres minimum block size required under Victorian regulations—to accommodate a secondary dwelling. The side access was over three metres wide, which is the minimum for construction vehicle entry. We measured it ourselves; do not trust the listing photos. The sewer connection was within ten metres of the proposed build site—anything further and trenching costs escalate. The switchboard had capacity for an additional circuit. Every box we check before recommending a granny flat build came back positive [7].

## The Granny Flat Build: $100,000 That Changed Everything

We engaged our partner builder to construct a 30-square-metre, one-bedroom granny flat at the rear of the property. Under Victorian planning rules, any dwelling under 60 square metres requires only a building permit—no planning permit needed. That removes the single biggest source of delay and risk in small-scale development. No planning permit means no neighbour objections, no council panel hearings, no six-month waiting period while bureaucrats deliberate. You lodge the building permit, your builder starts when the permit is issued, and you are collecting rent four to five months later [8].

The total build cost was $100,000 inclusive. That covers everything: slab, frame, roofing, plumbing, electrical, kitchen, bathroom, internal finishes, connection to the existing sewer, and a separate meter box. Our client financed 80 per cent through their existing lender by doing a small equity top-up against the main property. The out-of-pocket cash requirement was $20,000.

Let me repeat that. Twenty thousand dollars in cash. Not $200,000. Not $100,000. Twenty grand.

The build timeline was just under five months from permit lodgement to handover. Our builder has done enough of these in the southeast corridor that the process is almost formulaic. Same floor plan. Same materials. Same subcontractors. That consistency keeps costs predictable and quality reliable.

The granny flat, once completed, rented immediately at $320 per week. There was no vacancy period. We had applicants lined up before the painter finished the second coat. In a market where vacancy sits below 1.5 per cent, a brand-new one-bedroom dwelling with its own entrance, kitchenette, and bathroom is essentially guaranteed to lease within the first open inspection.

Now watch what happens to the numbers.

Main house rent: $470 per week. Granny flat rent: $320 per week. Total weekly rent: $790.

Total investment: $700,000 purchase plus $100,000 build equals $800,000.

Gross rental yield: $790 multiplied by 52, divided by $800,000, equals 5.1 per cent.

At 5.1 per cent gross yield, the rental income essentially covers the mortgage repayments on a standard principal-and-interest loan at current interest rates. This property is close to cash-flow neutral from day one, with two independent income streams providing redundancy if one tenant vacates. If the main house goes empty for two weeks between tenants, the granny flat keeps paying. If the granny flat tenant leaves, the main house keeps the lights on. Dual income is not just about yield—it is about resilience [9].

## The Exit Strategy Nobody Talks About

Here is the part that separates good investors from average ones.

A 700-plus square metre block in Cranbourne with activity zone proximity is not just a rental asset. It is a development site waiting to happen.

In ten years—maybe sooner depending on market conditions—the original house will be approaching end of life. The granny flat will be ageing too. At that point, the owner has two choices.

Option one: demolish everything and subdivide the block into two or three lots. Sell the lots to a developer or build townhouses yourself. In today's terms, vacant land in Cranbourne sells for $350,000 to $400,000 per lot. Two lots from a single property is $700,000 to $800,000 in land value alone [10].

Option two: sell the entire site to a developer as a single parcel. Developers pay a premium for blocks with existing planning precedent and dual-frontage potential.

Either way, the capital growth over that decade—driven by population influx, infrastructure spending, and land scarcity—compounds on top of the rental income you have been collecting the entire time.

This is what I mean when I say we are not just buying houses. We are buying land with income attached. The house is temporary. The land is permanent.

## The Common Objections, Answered

I get three objections to this strategy almost every week.

First: "But Cranbourne is dodgy." I have addressed this above. You are investing, not hosting dinner parties. The tenants are there. The vacancy rate proves it. If you cannot separate emotional preference from financial logic, property investment may not be for you.

Second: "Why not buy a nicer house in a better suburb?" Because a nicer house in a better suburb costs $1.2 million and rents for $600 a week. That is a 2.6 per cent yield. You are bleeding cash every single month. You are betting everything on capital growth in a market that may or may not deliver. My clients prefer to own assets that pay for themselves.

Third: "Granny flats are a hassle." They can be, if you use the wrong builder or skip the compliance checks. We have built dozens. Our process is industrialised. Building permit, not planning permit. Established builder relationships with fixed-price contracts. Tenant placement handled by our property management team. The hassle is a one-time, five-month process. The income is permanent [11].

I spent years making mistakes in property—paying too much tax, choosing the wrong ownership structure, ignoring cash flow in favour of chasing capital growth in expensive postcodes. Those mistakes taught me that the only sustainable investment strategy is one where the asset pays for itself from day one. Cranbourne, with a granny flat, does exactly that.

## What This Means for Your Portfolio

If you are sitting on a budget of $700,000 to $800,000 and wondering where to deploy it, I want you to consider this comparison.

Scenario A: You buy a two-bedroom apartment in Richmond for $750,000. It rents for $450 a week. Your yield is 3.1 per cent. You are losing money every month after mortgage repayments, strata fees, and council rates. The land component of your purchase is effectively zero because you own a fraction of a building [12].

Scenario B: You buy a three-bedroom house on 700-plus square metres in Cranbourne for $700,000. You add a granny flat for $100,000. Your total outlay is $800,000. You earn $790 a week. Your yield is 5.1 per cent. Your mortgage is covered. You own 100 per cent of the land. And in ten years, you have a subdivision-ready site.

The numbers do not lie. And as an actuary, I can tell you—numbers are the only thing I trust.

If you are interested in exploring a granny flat strategy for your next investment, or if you already own a property with a large backyard and want to know whether it qualifies for a secondary dwelling, reach out. I have seen too many investors leave money on the table by ignoring what is sitting right behind their house.

I am Yan, actuary turned buyer's agent. I will be back with more numbers next week.

## References

1. [PremiumRea client transaction records, Cranbourne 2021. Dual-income property generating $790/week on $800K total investment.](#)
2. [City of Casey, Cranbourne Town Centre Structure Plan. Activity zone designation and commercial precinct infrastructure.](https://www.casey.vic.gov.au)
3. [ABS Census 2016, Cranbourne median household income data. SA2 level income and affordability calculations.](https://www.abs.gov.au)
4. [Victorian Government, Victoria in Future 2019. Population projections for Casey–Cardinia growth corridor.](https://www.planning.vic.gov.au)
5. [SQM Research, Cranbourne residential vacancy rates, Q1 2021. Vacancy consistently below 1.5 per cent.](https://sqmresearch.com.au)
6. [PremiumRea due diligence checklist. Flood overlay, bushfire, easement, powerline, and slope assessment conducted pre-purchase.](#)
7. [Victorian Building Authority, Guide to Dependent Person's Units (Granny Flats). Minimum block size and access requirements.](https://www.vba.vic.gov.au)
8. [Planning and Environment Act 1987 (Vic), Clause 52.18. Buildings and works not requiring a planning permit for dwellings under 60sqm.](https://www.legislation.vic.gov.au)
9. [PremiumRea rental yield calculation. $790/week x 52 weeks / $800,000 total cost = 5.14% gross yield.](#)
10. [CoreLogic RP Data, Cranbourne vacant land sales 2020-2021. Median lot price $350,000-$400,000 for 300-350sqm lots.](https://www.corelogic.com.au)
11. [PremiumRea granny flat build pipeline. Average build time 4.5-5.5 months from permit lodgement to tenant placement.](#)
12. [Domain Group, Melbourne apartment rental yield data Q1 2021. Inner-city two-bedroom apartment median yield 2.8-3.2%.](https://www.domain.com.au)

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Source: https://premiumrea.com.au/blog/cranbourne-granny-flat-700sqm-790-week-case-study
Publisher: PremiumRea (Optima Real Estate) — Melbourne buyers agent