Indicative investment assessment

Secondary dwelling feasibility

The most comprehensive feasibility tool for secondary dwelling investments in South East Queensland. Regions covered by this tool — Brisbane, Ipswich, Logan, Moreton Bay, Redlands and Sunshine Coast.

01

Property details

Existing property details and key investment fundamentals.

Link to the REA listing

Optional. Prints on the first page of the report so the reader can open the listing themselves.

URL

Addresses from the Queensland address register — pick one and the suburb and council fill automatically.

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m²
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m²

Optional. Prints on the property page of the report, as written. Your own words or the listing's.

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Building and pest inspection, conveyancer, accounting and miscellaneous acquisition costs. Leave blank for none.

Primary dwelling capital works

Scope of works Essential Cost
Essential costs $0 Renovation or repair works to the existing dwelling to achieve the market rent. Essential costs are added to the cost of the property alongside transfer duty and acquisition costs; optional costs are recorded but not costed into the feasibility. Optional costs $0 Total $0

A clearer first decision

From property inputs to an investable summary.

01

Property & market

Match the property to the Queensland suburb and council dataset.

02

Design & funding

Test four secondary dwelling designs, valuation uplift and LVR assumptions.

03

Site & approvals

Add overlays, infrastructure charges and the works needed for a tenant-ready home.

04

Feasibility result

See total cost, equity required, rent, yield and the model's hurdle result.

Model notes

Important assumptions

This calculator translates the Marsh Homes Secondary Dwelling Feasibility model into an interactive estimate. Market guidance is drawn from its July 2026 suburb dataset (realestate.com.au suburb profiles). All prices include GST.

  • The yield hurdle is a subjective measure with no defined industry standard. A 5.0% gross yield hurdle is adopted for suburbs whose median house yield is above 3.5%, and 4.5% at or below 3.5%. Source: realestate.com.au suburb profiles.
  • Gross yield is calculated on the property purchase (including any essential capital works) and secondary dwelling costs, including the dwelling's approvals and statutory charges. Transfer duty and other acquisition costs are excluded from the yield, as is industry standard, and included in the equity required. The yield excludes vacancy, management, maintenance, interest and tax.
  • The feasibility runs on the market rent entered for the primary dwelling, not the current rent, which is recorded for reference.
  • Interest is charged on the loan drawn at the target LVR against the as-if-complete valuation, at a long-term average of — a year held constant. It is the Reserve Bank's discounted variable investor rate averaged over its full published life, so it is a long-run average and not a forecast — short-term interest costs will differ. Interest shown against the primary property and the secondary dwelling separately is the whole loan split by the security each contributes to the valuation.
  • Rent is escalated at — a year less a — management fee, and capital value grows at — a year. Where any of these is adjusted on the summary, the rate returns linearly to the adopted figure so the ten-year average is unchanged.
  • Transfer duty uses Queensland investment-purchase brackets.
  • QBCC home warranty premiums use the table effective 1 July 2020 and require current confirmation.
  • QLeave is modelled at 0.575% where construction is at least $150,000.
  • Infrastructure charges and compliant-size settings are indicative and must be checked with the relevant authority.
  • Consultancy agreement and infrastructure charges are always equity-funded.