Duplex The Spit — Feasibility, Design, Approval & Build
End-to-end duplex delivery in The Spit 2088: yield analysis, design for R2 Low Density zoning, Mosman Council approvals, subdivision coordination, construction, separate services and handover.
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MBA NSW0476 300 300Quick Answer
A duplex in The Spit costs $750,000–$1,500,000+ for dual occupancy construction. Attached duplex from $750K, detached from $1M. Buildana manages feasibility, Mosman Council approvals, construction and subdivision under one fixed-price contract.
Building Duplexes in The Spit
A duplex at The Spit is almost never the right call, and the market tells you why. This is harbour-fall land at the southern end of the Spit Bridge, Federation mansions and contemporary harbour builds on 600 to 1,500m2 blocks, with a $4.5M to $10M market driven purely by the Middle Harbour outlook. The blocks clear the 650m2 Mosman minimum easily, but a single premium home makes far more of that outlook than two dwellings.
Where a duplex could be justified, it is a large family hold rather than a sale play. Heritage Conservation Areas cover most older streets, so that is checked first. The ground is sandstone-dominant with deep rock excavation typical, so a single build already carries serious cost, and splitting it in two rarely pays.
What I would check first on your The Spit block: the heritage status and the rock, then whether a single premium home or a considered dual-occupancy makes more of the harbour position.
We build these fixed-price, licence HBL 487805C. Send me the block and I will tell you honestly what suits it.
Buildana manages the full duplex development process in The Spit — from feasibility assessment and architectural design through to DA or CDC approval, and fixed-price construction to dual handover. One builder, one contract, two homes.
Read our Complete Duplex Building Guide or explore duplex developments across Sydney.
- Dual occupancy in The Spit from $750K
- Mosman Council DA and CDC approvals managed
- R2 and R3 zones — established dual occ. provisions
- Minimum lot size 650m² in The Spit
- M — engineered dual-slab design included
- Strata or Torrens title subdivision available
- 6-year structural warranty per dwelling
- Free feasibility check — near North Sydney (7 km) station
Reviewed by Oliver Alameri
Licensed Builder (NSW 487805C) · Master of Property Development · PhD Student · Building across Western Sydney since 2010
Harbour outlook favours a single home
The Spit runs 600 to 1,500m2 blocks that clear the 650m2 Mosman minimum easily.
At a $4.5M to $10M market a single premium home makes far more of the Middle Harbour outlook than two dwellings.
Heritage and deep rock
Heritage Conservation Areas cover most older streets, checked first.
Sandstone-dominant ground with deep rock excavation typical means serious cost even on a single build.
Duplex builder in The Spit — key facts
- Suburb
- The Spit, NSW 2088
- Council / LGA
- Mosman Council (Mosman)
- Primary zoning
- R2 Low Density
- Typical lot size
- 600–1,500m²
- Soil class
- M
- Median house price
- $4.5M–$10M
- Home era
- 1900s–1950s heritage
- Typical price range
- $750,000 – $1,500,000+
- Typical timeline
- 14–22 months design to handover
- Approval pathway
- CDC for compliant dual-occupancy, else DA
Want a real number for YOUR block — not a generic estimate?
Free site assessment, fixed-price contract, line-itemised quote within 48 hours. No high-pressure sales — just a real builder talking real numbers.
How It Works
From First Call to Final Key
Free feasibility check on your The Spit block. We measure frontage width, confirm zoning (R2 Low Density), check minimum lot size against 650m² requirement, and review Mosman Council's DCP controls. Written feasibility report within 5 business days.
⏱Two dwellings, one site — design is mostly about geometry. Frontage split, party wall position, garage stacking, private courtyard size, and the streetscape elevation a certifier will actually approve. We work the design until both sides feel like proper homes, not mirror-image apartments.
⏱DA through Mosman Council (40–90 days) or CDC (10–15 business days). The Spit is zoned R2 Low Density. Construction Certificate obtained before works commence.
⏱Dual construction runs 9–14 months. Engineered slabs sized for Class M soil, simultaneous frame-up, staggered fit-out for efficiency. Your project manager coordinates all trades and inspections.
⏱Two homes, two titles, two OCs, two warranty packs. We hand over a clean documentation set per dwelling: certifier reports, BASIX certs, structural sign-offs, appliance warranties, maintenance schedules. Whatever the next owner or buyer asks for is in the file.
⏱Quality Promise
Every Buildana duplex in The Spit is built under a fixed-price contract — feasibility through to dual handover and subdivision.
Cost Guide
| Item | Estimated Range |
|---|---|
| Attached duplex (side-by-side) | $1,050,000 – $1,540,000 |
| Attached duplex (stepped/offset) | $1,260,000 – $1,750,000 |
| Detached duplex (two fully separate dwellings) | $1,680,000 – $2,240,000 |
| Luxury detached duplex | $2,240,000+ |
| Party-wall acoustic & fire upgrade | Included |
Prices are indicative for Western Sydney (2025). Actual costs depend on site, specifications, and approvals.
Our Team
Oliver Alameri
Founder / Director / Builder · MPropDev · PhD Student
Ahmad Alameri
Accounts Manager
Claire Wendell
Project Manager
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Still got questions? Talk to Oliver directly.
30-min free call — bring your block, your brief, your budget. We'll map out feasibility, timeline, and realistic cost. No sales pitch.
Frequently Asked Questions
Buildana built our granny flat in just 12 weeks. Fast approvals, great communication, and a beautiful final product. Highly recommend.
Fatima Al-Rashid
Liverpool, NSW
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Last updated: 1 July 2025
Duplex in The Spit — Book Site Assessment
Free duplex feasibility assessment for The Spit 2088. We'll check your block, estimate yield, and provide a fixed-price budget.
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Other Buildana services in The Spit
Costs, approval pathway and fixed-price contract detail for every other build type we deliver in The Spit 2088. Mosman Council regulations and local controls are covered on each page.