Investment Granny Flats: A Case Study

When it comes to improving return on investment through renovations, it can be helpful to think outside the box.

Something investors might not have considered is a granny flat – an increasingly popular approach for improving ROI. A separate building is the most common choice, but depending on the property, there is also the option to reconfigure part of a house to encompass a granny flat.

Case study

In 2017, one of our owners purchased a four-bedroom, two-garage home in Aberglasslyn for $408,000 (+stamp duty). Potential was identified to convert the property to a three-bedroom, one-bathroom house with a one-bedroom, one-bathroom granny flat.

This renovation would have a dual purpose: increasing rental income and achieving overall capital growth.

A designer, private certifier and builder were engaged, with planning permission engaged afterward to speed up the process.

The project was initially expected to take five months, but was extended to seven months.

Granny flat shown in outline above.

 BEFORE                                            AFTER 

Rent: $390/week                                     Rent: $640/week (combined)

Sale value:   
                                           Sale value (estimated):
$408,000                                                  $530,000

This equates to $13,000 additional annual income and 9.9% ROI on the total cost of the improvements (approx. $131,000, inclusive of vacancy period).

The new sale value is not yet confirmed by a sales agent, but the owners were advised that the new price would be equivalent to the purchase price plus the cost of renovations. On that basis, the sale value is estimated to be in the vicinity of $530,000.

Works completed

  • Firewall built between main property and granny flat
  • Roof altered to achieve the above (unanticipated cost)
  • Hallway reconfigured
  • Kitchen and laundry facilities added to granny flat
  • Separate living areas and gardens established
  • Painting completed
  • New blinds installed
  • Carpets cleaned
  • Landscaping completed and pergola added
  • Alarm system added
  • Fencing and security mesh installed
  • Currently considering adding a carport for granny flat.
Granny flat interior
Backyard before (Image via realestate.com.au)
Backyard after


If you’re interested in discussing potential renovations to improve your property’s return on investment, chat to your property manager, or get in touch with our Investment Services team.

Leah Jay charges 5.5% on invoice costs (inc. GST) for all facilitation of property improvement/refurbishments.

Disclaimer: This information is general in nature and does not take into account your personal situation. You should consider whether the information is appropriate to your situation, and for professional advice, seek out a financial adviser.


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