Duplex Builder St Marys — From $750K Fixed Price
Fixed-price duplex construction in St Marys 2760. Two dwellings, one contract, no variations. Minimum lot 450m² under Penrith DCP 2014 (lower than most LGAs). Free feasibility.
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MBA NSW0476 300 300Quick Answer
A duplex in St Marys costs $750,000–$1,500,000+ for dual occupancy construction. Attached duplex from $750K, detached from $1M. Buildana manages feasibility, Penrith City Council approvals, construction and subdivision under one fixed-price contract.
St Marys Duplex Construction
A duplex in St Marys works on the R2 side streets, and Penrith's low duplex minimum helps the case. Lots run 450 to 750m2 against a 450m2 minimum under the Penrith DCP, so a large share qualify, though R3 and R4 redevelopment is ramping around the station ahead of the Western Sydney Airport rail link. On a $850K to $1.3M market, a Torrens-title duplex on a qualifying side-street block is a sound investor play.
The ground is Wianamatta Shale, so footings and the slab are engineered to suit, and the older fibro and brick stock nearly always carries asbestos, stripped under licence. Industrial-legacy contamination on the eastern edge needs checking where it applies.
What I would check first on your St Marys block: the zoning, the area against the low 450m2 minimum, and any eastern-edge contamination overlay.
We build these fixed-price, licence HBL 487805C. Send me the block and I will tell you what it carries.
Buildana manages the full duplex development process in St Marys — 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 St Marys from $750K
- Penrith City Council DA and CDC approvals managed
- R2 and R3 zones — established dual occ. provisions
- Minimum lot size 450m² under Penrith DCP 2014 (lower than most LGAs) in St Marys
- M — engineered dual-slab design included
- Strata or Torrens title subdivision available
- 6-year structural warranty per dwelling
- Free feasibility check — near St Marys station
Reviewed by Oliver Alameri
Licensed Builder (NSW 487805C) · Master of Property Development · PhD Student · Building across Western Sydney since 2010
R2 side streets, low minimum
St Marys lots run 450 to 750m2 against a 450m2 Penrith minimum, so a large share of side-street blocks qualify.
R3 and R4 redevelopment is ramping around the station ahead of the airport rail link, so the side streets are where a duplex fits.
Shale, fibro and contamination
The Wianamatta Shale means footings and slab engineered to suit, with older fibro stripped of asbestos under licence.
Industrial-legacy contamination on the eastern edge is checked where it applies before design.
Duplex builder in St Marys — key facts
- Suburb
- St Marys, NSW 2760
- Council / LGA
- Penrith City Council (City of Penrith)
- Primary zoning
- R2
- Typical lot size
- 450–750m² typical (Cranebrook/Werrington/Cambridge Park/Kingswood/St Marys); 250–450m² master-planned (Jordan Springs/Caddens/Glenmore Park new release)
- Soil class
- M
- Median house price
- $850K–$1.3M typical; $1.0M–$1.6M Glenmore Park/Jordan Springs premium master-planned; $1.6M–$3.0M+ Mulgoa/Wallacia/Castlereagh acreage
- Home era
- 1950s–1980s + 2010s+ R4 apartments
- 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.
Cost Guide
| Item | Estimated Range |
|---|---|
| Vacant R2/R3 block in St Marys — duplex build | $750,000 – $1,500,000 |
| KDR duplex (demo 1950s–1980s + 2010s+ R4 apartments home + dual build) | $820,000 – $1,600,000 |
| Subdivision-ready block (existing survey & titles) | $750,000 – $1,400,000 |
| Corner block dual-frontage duplex | $900,000 – $1,600,000 |
| Investor scenario (neutral-gear focus, rental-ready) | $850,000 – $1,250,000 |
Prices are indicative for Western Sydney (2025). Actual costs depend on site, specifications, and approvals.
How It Works
From First Call to Final Key
Feasibility covers the planning side and the financial side. Yes-or-no on whether the block supports dual occupancy under Penrith City Council controls, plus indicative end values, build cost, and likely yield.
⏱Dual occupancy floor plans designed for your St Marys block — attached or detached configuration, vehicle access, private open space, and full Penrith City Council compliance..
⏱Full approval management: Statement of Environmental Effects, plans, reports, and all supporting documentation lodged with Penrith City Council or private certifier. We handle RFIs and conditions.
⏱Construction follows a tight programme: dual slabs in one mobilisation, paired frame stand, simultaneous lock-up, then trades rotate between sides for fit-out so no day is lost waiting on availability. The schedule is engineered, not optimistic.
⏱Both dwellings handed over with individual Occupation Certificates. Subdivision lodged for separate titles.
⏱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.
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Liverpool, NSW
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Last updated: 1 July 2025
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Other Buildana services in St Marys
Costs, approval pathway and fixed-price contract detail for every other build type we deliver in St Marys 2760. Penrith City Council regulations and local controls are covered on each page.