Funding your build

Granny flat finance —four ways owners actually pay for the build.

Most owners don't write a $121k inc GST cheque. They release equity from the home they already own, or draw a construction loan in stages as the build progresses. Here are the four funding paths we see on real E2ES projects — with a fully worked cash-flow example, the post-completion revaluation play, and the questions every lender will ask.

By Yan Zhu · Co-Founder & Chief Data Officer, E2ES

The four funding paths

Every E2ES client funds their build through one of these four routes. We are builders, not lenders — but we work alongside licensed mortgage brokers every week and can refer you to one who knows granny flat lending inside out.

① Equity release / top-up on your existing home

The most common path by far. Lenders rarely write a construction loan secured against a granny flat alone — the granny flat sits on the same title as your main house, so there is no separate security to lend against. Instead, your broker tops up (or splits) the existing mortgage against your home's current equity. If your house is worth $850k and you owe $500k, most lenders will let you borrow up to 80% of value ($680k) — releasing up to $180k without Lenders Mortgage Insurance. The funds land as cash, so you can pay E2ES's staged invoices directly with no bank inspections between stages. Fastest approval of the four paths, usually 2–4 weeks.

Best forOwners with 20%+ equity in their current home — which is most owners who bought before 2022.

② Construction loan

The structured route: 20% of the ex-GST build price plus all GST in cash (~$33k–$46.5k for the Victorian 34 m² / 60 m² illustrations), with 80% of the ex-GST build price drawn down in four stages that mirror the build — slab, frame, lock-up, fit-out. You pay interest only on what has been drawn, at investment interest-only rates of about 6.3% p.a. (2026 market), so the interest bill ramps up gradually across the three-month construction programme instead of hitting on day one. The lender sends a valuer to sign off each stage before releasing the next payment. Slower to arrange than a top-up (allow 4–6 weeks) and more paperwork, but it suits owners who want the build debt ring-fenced from the family home loan.

Best forInvestors who want the build debt separated, or owners whose existing loan can't be topped up.

③ SMSF (self-managed super fund)

Possible, but the most heavily regulated path. Borrowing inside super must comply with section 67A of the Superannuation Industry (Supervision) Act — a limited recourse borrowing arrangement (LRBA) — and the ATO takes the view that borrowed SMSF money generally cannot fund improvements that change the character of an existing asset, which catches many granny flat builds on an already-owned SMSF property. If the fund buys the property and builds with its own cash (no borrowing), the rules are more workable. Two hard lines either way: you and your relatives cannot live in it, and you cannot rent it to related parties. This is licensed-advice territory — talk to an SMSF-accredited financial adviser and accountant before signing anything. We can refer you to brokers who work on SMSF granny flat projects.

Best forTrustees with an SMSF-held investment property and professional advisers already in place.

④ Cash

The simplest path: pay the staged invoices as they fall due, keep the asset unencumbered, and keep 100% of the rent. On the 34 m² plan the target rent is $380/wk — $19,760 a year before any costs — against a $121k inc GST all-in build price including connections. Rent divided by the build price is not a rental yield (it leaves out the land, vacancy and every holding cost). E2ES owner-stated upper range (21 October 2026): rooming-house gross yield of up to 13% in Melbourne and up to 15% in Queensland — not a forecast; the result depends on site, rents, vacancy and costs. The trade-off is opportunity cost: many investors deliberately borrow anyway, because the interest is tax-deductible on an income-producing build and the preserved cash funds the next deposit.

Best forDownsizers, business owners with cash reserves, and owners who value simplicity over leverage.

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Victorian worked example — 34 m² Compact Studio, financed

The numbers below use the E2ES fixed price and a illustrative interest-only rate. Your rate, rent and costs will differ — treat this as a template, not a promise.

Build price (34 m² Compact Studio)$121,000 inc GST
Cash contribution (20% ex-GST + all GST)~$33,000
Amount financed$88,000
Rate assumption (investment, interest-only)~6.3% p.a.
Interest cost≈ $107 / week
Typical rent (34 m² studio, metro Melbourne)≈ $380 / week
Net cash flow before running costs≈ +$273 / week

Before running costs means before property management (~7–8% of rent if you outsource), insurance, extra council rates, maintenance and vacancy. Even with a conservative $70–$90/wk allowance for all of those, the studio remains solidly cash-flow positive from the first tenant — the rent covers the loan roughly 3.5 times over.

After the build: revaluation, refinance, depreciation

The OC-triggered revaluation. The moment your occupancy certificate (OC) is issued, the granny flat stops being a construction project and becomes recognised, income-producing floor area. Lenders will now order a new valuation of the whole property. A compliant, certified second dwelling is usually counted in that valuation, but how much it adds depends on your lot, the valuer and the market at the time. We do not estimate it, and no one can promise it will exceed what you spent.

Refinancing to release the uplift. That revaluation is not just a number on paper. Many E2ES investor clients refinance within 1–3 months of OC: the higher valuation drops their loan-to-value ratio, which unlocks a further equity release — often enough to cover the deposit on the next investment property. The granny flat effectively becomes the deposit factory for purchase number two. A broker can usually run the top-up against the new valuation in 2–4 weeks.

Depreciation. A brand-new granny flat is one of the most depreciation-rich assets per dollar in Australian residential property, because 100% of the build is new construction. As a rule of thumb, an illustrative $110k ex-GST capital-works base (within the $121k inc GST build price) supports roughly $2,750/yr in Division 43 capital works deductions (2.5% p.a. over 40 years), plus Division 40 plant-and-equipment deductions (hot water heat pump, air conditioner, appliances) that are front-loaded in the early years. Order a quantity surveyor (QS) depreciation schedule after handover — it costs $600–$800 once, is itself tax-deductible, and typically pays for itself several times over in year one. Your accountant applies it at tax time.

Granny flat finance FAQs

Important disclaimer

E2ES (Optima Real Estate) is a residential builder. We are not a licensed credit provider, mortgage broker, financial adviser or tax agent, and nothing on this page is credit, financial, tax or investment advice. All rates, valuations, rents, deductions and cash-flow figures are general illustrations only — they do not take your personal objectives, financial situation or needs into account, and they will differ from your actual outcome. Before making any borrowing or investment decision, obtain advice from an Australian Credit Licence holder (for lending), a licensed financial adviser (for SMSF and investment decisions) and a registered tax agent (for depreciation and deductions). Where we refer you to a broker or adviser, they are independent licensed professionals and you are under no obligation to use them.

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