The best duplex outcome on the Northern Beaches is often not selling both. It is selling one and moving into the other with no mortgage.
How it works
- You own a house on a 600 m²+ block inside an LMR ring. It has a mortgage.
- We prove the block holds two homes. Approval, then build.
- On completion, you sell one. The sale clears the construction loan and the old mortgage.
- You move into the other. Brand new, four bedrooms, Torrens title, no debt.
One sale clears both loans; the home you keep is the new one.
Same street. Same school. Same neighbours. New house. No repayments.
The three versions
- Keep and live. The one above. The family stays, the mortgage goes.
- Keep and rent. Sell one, keep one as an investment. The rent covers what is left of the loan, and you hold a new asset in a market where new stock is scarce.
- Sell both and walk away clean. You take the full profit and buy whatever you want next. The site on our portfolio page marked “Kept one, sold one” in Forestville went the first way. Plenty go the third.
Where you live during the build
The honest answer: not on site. A duplex build means the existing house comes down. Most owners rent nearby for 14 to 20 months. Some move in with family. We factor the rent into the feasibility so the number you see is the real one. If you have a granny flat or a second property, that changes the picture for the better.
Why the keep-one option often beats selling both
- You avoid agent fees and marketing on the second home.
- You avoid stamp duty on buying your next place.
- You stay in a suburb you chose for a reason.
- The home you keep is new. New roof, new plumbing, new warranty. Maintenance drops to near zero for a decade.
The tax question
Keeping one and selling one has tax consequences that depend on your situation — main residence exemption, timing, whether you are treated as carrying on a business. We are not your accountant and we will not pretend to be. We will put you in front of one before you commit, and we will build the structure the accountant recommends into the plan from day one.
Who this suits
Owners in their 40s to 60s on a block they have held for years. The mortgage is manageable but it is still there. The kids are in local schools, or they have left and the house is too big. The land has quietly become the biggest asset in the family. Keep one, sell one turns that paper value into a new home and a clear title without leaving the street.
Start with the block
None of this works unless the land qualifies. That is the two-minute check. Then it is a conversation at the showroom with the plans on the table.