Duplex Builder Mortlake — From $750K Fixed Price
Fixed-price duplex construction in Mortlake 2137. Two dwellings, one contract, no variations. Minimum lot 600m². Free feasibility.
HIA Member
MBA NSW0476 300 300Dual Occupancy Developments in Mortlake
Duplex in Mortlake works R2 detached pockets outside HCAs meeting 600m² minimum. End values $2.2M–$3.2M per attached dwelling. Mandatory paid feasibility.
On the ground in Mortlake (2137), the practical numbers shape every duplex development. Class M–H (Wianamatta Shale) / H (river/bay fall) soil — moderately to highly reactive clay — pushes engineered foundation work into the $24,000–$42,000 bracket on most 400–800m² blocks. R2 Low / R3 Medium / R4 (Rhodes/Concord West) zoning under City of Canada Bay Council sets the building envelope, with R3 Medium Density pockets that open up dual occupancy options on qualifying lots. Median sale price across Mortlake sits at $1.9M–$3.5M, which frames the build-versus-buy decision from the start. Nearest rail is North Strathfield (2 km) / Mortlake ferry to Putney, and that proximity affects everything from rental demand to construction site access.
Buildana manages the full duplex development process in Mortlake — 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 Mortlake from $750K
- City of Canada Bay Council DA and CDC approvals managed
- R2 and R3 zones — established dual occ. provisions
- Minimum lot size 600m² in Mortlake
- Class M–H (Wianamatta Shale) / H (river/bay fall) soil — engineered dual-slab design included
- Strata or Torrens title subdivision available
- 6-year structural warranty per dwelling
- Free feasibility check — near North Strathfield (2 km) / Mortlake ferry to Putney station
Reviewed by Oliver Alameri
Licensed Builder (NSW 487805C) · Master of Property Development · PhD Student · Building across Western Sydney since 2010
Why Build a Duplex in Mortlake?
Mortlake is the riverside suburb adjacent to Breakfast Point — Federation cottages, inter-war heritage, post-war stock and contemporary on 400–800m² blocks. Heritage Conservation Areas cover several streets. Wianamatta Shale soil. Mortlake Wharf with Putney ferry connection.
Mortlake sits in the City of Canada Bay local government area with 400–800m² residential blocks and R2 Low / R3 Medium / R4 (Rhodes/Concord West) zoning. Building costs are around the Sydney metro average, balancing construction value with lifestyle and growth. Transport access via North Strathfield (2 km) / Mortlake ferry to Putney connects Mortlake to the wider Sydney network. Dual occupancy is well-established in Mortlake's R3 zones. Minimum lot size for duplex: 600m². Ground conditions (Class M–H (Wianamatta Shale) / H (river/bay fall)) across Mortlake are well understood by local builders — Buildana's engineering accounts for moderately to highly reactive soil movement.
Duplex feasibility in Canada Bay is one of Sydney's strongest mid-tier markets — R2 detached pockets meeting 600m² minimum cover most of Concord, Five Dock, Russell Lea, Canada Bay, Wareemba, Mortlake and North Strathfield outside HCAs. R3 along Lyons Road, Great North Road, Concord Road and Parramatta Road permits attached duplex with stronger end-value yield. End values $2.2M–$3.5M per attached dwelling typical, $3M–$5M+ on river-fall premium peninsulas (Drummoyne, Abbotsford). Five Dock Metro 2030 is reshaping feasibility — station-precinct sites carrying density bonuses already trading at premium. Heritage Conservation Areas effectively rule out duplex on the riverside peninsulas (Abbotsford, Chiswick, Cabarita, parts of Drummoyne, Rodd Point). Mandatory paid feasibility — site selection determines everything.
Planning Controls — City of Canada Bay Council
Canada Bay LEP 2013 & Canada Bay DCP 2017. R2 Low Density covers most older residential streets: FSR 0.5–0.55:1, building height 8.5–9m, front setback 6–7.5m, landscaped area 35–40%. R3 Medium Density along Lyons Road, Great North Road, Concord Road and Parramatta Road permits FSR up to 0.85:1. R4 High Density and B4 Mixed Use concentrated on Rhodes peninsula (Rhodes Waterside, Concord Road towers), Concord West / North Strathfield station precincts, and Five Dock village (gearing up for Sydney Metro West 2030 — Five Dock station precinct already designated TOD). Heritage Conservation Areas cover the riverside peninsulas (Abbotsford, Chiswick, Cabarita, Mortlake, Drummoyne) plus pockets in Concord, Five Dock, Russell Lea, Wareemba, Rodd Point. Tree Preservation Order LGA-wide. Wianamatta Shale soil with sandstone outcrops on the river-fall peninsulas — fall to Parramatta River, Iron Cove, Hen and Chicken Bay, Canada Bay drives suspended slab engineering on premium river-fall lots. Five Dock Sydney Metro West (under construction, opening 2030) is the LGA's signature planning event — station-precinct overlay opens density bonuses inside 400m of Five Dock station. Rhodes peninsula has industrial-legacy soil contamination management protocols on remediated former Union Carbide site.
Duplex builder in Mortlake — key facts
- Suburb
- Mortlake, NSW 2137
- Council / LGA
- City of Canada Bay Council (City of Canada Bay)
- Primary zoning
- R2 Low / R3 Medium / R4 (Rhodes/Concord West)
- Typical lot size
- 400–800m²
- Soil class
- Class M–H (Wianamatta Shale) / H (river/bay fall)
- Median house price
- $1.9M–$3.5M
- Home era
- 1900s–1960s
- 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
Building in Mortlake — Local Context
Mortlake Block Realities
Typical Mortlake blocks are 400–800m² on Class M–H (Wianamatta Shale) / H (river/bay fall) ground (moderately to highly reactive clay). For a duplex, the structural envelope is more constrained than the headline lot size suggests — once you subtract setbacks, easements, landscaped area requirements, and any tree preservation, the actual buildable area is usually 35-45% of the block. We map that early in the feasibility stage so you're designing to what's actually allowed, not what looks possible from the title plan. Foundation cost band on most Mortlake blocks: $24,000–$42,000.
Planning Controls in Mortlake
Mortlake is zoned R2 Low / R3 Medium / R4 (Rhodes/Concord West) with R3 Medium Density pockets. City of Canada Bay Council controls FSR, height limits (typically 8.5–9m), site coverage, landscaped area minimums, and setbacks. For a duplex, the binding constraints on most 400–800m² blocks here are: front setback (around 4.5–6m), side setbacks (1.0–1.5m articulated), rear (3–6m depending on lot depth), and landscaped area (usually 35–40%). Buildana's design team works to those numbers from the first sketch — no late re-design when council comes back with comments.
Where the Money Goes on a Mortlake Duplex
Cost breakdown for a typical duplex in Mortlake: structure and frame around 30%, slab and foundations 8–14% (driven by Class M–H (Wianamatta Shale) / H (river/bay fall) soil), roofing and external 10–12%, services (plumbing, electrical, HVAC) 12–18%, fit-out (kitchen, bathrooms, joinery) 18–25%, and finishes (paint, tiles, flooring) 8–12%. The remaining 4–6% covers approvals, certifications, and site establishment. Buildana itemises every line so you see what you're paying for — no lump sums hiding margin.
Designing for the Mortlake Streetscape
Mortlake's housing stock is predominantly from the 1900s–1960s. North Strathfield (2 km) / Mortlake ferry to Putney from the nearest station. The local anchor is Mortlake ferry wharf. For a duplex development, the streetscape question matters more than most builders admit — a brand-new double-storey on a street of single-storey 1900s–1960s weatherboards will draw council attention on bulk and scale, even if technically compliant. Buildana designs the front elevation to read appropriately for the street while modernising the floor plan and structure behind it. Materials palette, roof pitch, fenestration rhythm — all chosen to settle into the existing rhythm rather than fight it.
What Recent Approvals Show
City of Canada Bay Council's recent decisions for Duplexs in Mortlake reveal a clear pattern — applications that lock in compliant FSR (under 0.5:1 in most cases), maintain proper articulation, and address neighbour overshadowing on the front foot are getting through cleanly. Sloppy lodgement adds 4-8 weeks of round-trip; clean lodgement doesn't.
Builder's Take on Mortlake
One Mortlake mistake I see: duplex owners trying to maximise floor area and ending up with zero garden. Buyers and tenants in this area value a usable backyard more than an extra 15m² of living room. Good dual occ. design leaves both dwellings with genuine private open space.
The real edge on Mortlake duplex projects is sequencing. Two slabs on one pour, two frames standing up the same week, two sets of trades rolling in convoy. If each dwelling is treated as a separate build, the programme blows out by 8–12 weeks. We build them as one job.
Mortlake vs Nearby Suburbs
Mortlake vs nearby suburbs — key metrics for building a duplex.
| Suburb | Median Price | Typical Lot | Soil Class | Min Duplex Lot | Station |
|---|---|---|---|---|---|
| Mortlake2137this suburb | $1.9M–$3.5M | 400–800m² | Class M–H (Wianamatta Shale) / H (river/bay fall) | 600m² | North Strathfield (2 km) / Mortlake ferry to Putney |
| Cabarita2137 | $2.5M–$5M | 500–1,000m² | Class M–H (Wianamatta Shale) / H (river/bay fall) | 600m² | North Strathfield (2 km) |
| Breakfast Point2137 | $2.0M–$4M | 200–500m² | Class M–H (Wianamatta Shale) / H (river/bay fall) | 600m² | North Strathfield (3 km) |
| Concord2137 | $2.2M–$4M | 500–900m² | Class M–H (Wianamatta Shale) / H (river/bay fall) | 600m² | Concord West (1 km) |
Median price, soil class, and lot size shape build feasibility and final cost. Buildana assesses every site against these and other constraints during the free feasibility stage.
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Quality Promise
Buildana delivers Mortlake duplexes as a single project — one contractor accountable from site check to subdivision.
How It Works
From First Call to Final Key
A duplex is really a feasibility problem wearing a construction outfit. Before anything else, we verify your Mortlake block against City of Canada Bay Council's LEP — lot size, frontage, FSR, landscape area. If it doesn't stack up, you find out in a week, not after 3 months of design.
⏱Design runs dual from day one. Two dwellings, one coherent streetscape, party-wall acoustics and fire rating built into the structure rather than bolted on. The plan accommodates R2 Low / R3 Medium / R4 (Rhodes/Concord West) zoning without looking like two mismatched houses sharing a fence.
⏱Approval and construction get sequenced together. Slab pours are choreographed so the trades show up once, frame up both sides, and keep rolling. Two separate meters, two separate services, but one crew, one programme.
⏱Handover is dual. Both dwellings walked at the same time, both OCs in the same issue, both titles subdivided before settlement. You leave the final inspection with the option to live in one and rent the other, or to sell both.
⏱Our Team
Oliver Alameri
Founder / Director / Builder · MPropDev · PhD Student
Ahmad Alameri
Accounts Manager
Claire Wendell
Project Manager
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Last updated: 1 July 2025
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