Home Extension Builder Mortlake — From $150K Fixed Price
Fixed-price home extensions in Mortlake 2137. Rear extension $150K–$300K, second storey $300K–$500K. City of Canada Bay Council approvals managed. Free site consult.
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A home extension in Mortlake costs $150,000–$600,000+. Rear extension from $150K, second-storey addition from $300K. Buildana manages design, City of Canada Bay Council approvals, and construction under one fixed-price contract.
Second-Storey & Rear Additions in Mortlake
Extension in Mortlake is Federation cottage and inter-war heritage additions on 400–800m² blocks. HCAs restrict scope on character streets. Realistic budget $280K–$750K for 70–130m² addition. Pre-construction 5–7 months.
On the ground in Mortlake (2137), the practical numbers shape every home extension. 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 complete home extension process in Mortlake — from design consultation and structural engineering through to DA or CDC approval, and fixed-price construction to handover. Extend your home without the stress.
Read our Home Extension Cost Guide 2026 or explore extension approval pathways in NSW.
- Home extensions in Mortlake from $150K
- City of Canada Bay Council DA and CDC approvals managed
- Ground floor, rear and second-storey additions
- Class M–H (Wianamatta Shale) / H (river/bay fall) soil — structural engineering included
- 1900s–1960s-era homes assessed for extension suitability
- Connect new to existing — clean, matched finish
- 6-year structural warranty
- Free design consultation — 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 Extend Your Home 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's mix of 1900s–1960s-era housing on 400–800m² blocks creates strong opportunity for property improvement. Median prices of $1.9M–$3.5M support quality build investment. Transport access via North Strathfield (2 km) / Mortlake ferry to Putney connects Mortlake to the wider Sydney network. 1900s–1960s-era homes in Mortlake often have good structural foundations worth building on. Extensions add living space at a fraction of the full rebuild cost. Soil conditions in Mortlake (Class M–H (Wianamatta Shale) / H (river/bay fall), moderately to highly reactive) are factored into every Buildana foundation design.
Extension is the dominant scope across the Canada Bay riverside heritage peninsulas (Abbotsford, Chiswick, Cabarita, parts of Drummoyne, Mortlake) where KDR is restricted. Federation cottage additions, inter-war heritage extensions, river-fall heritage-grade work all common. Suspended slabs on river-fall sites; foreshore consent on direct waterfront lots. Heritage Council expects retention of stained glass, ornate plasterwork, slate roofing on protected streets. Apartment renovations the other major category — Rhodes high-rise, Concord West / North Strathfield station precincts, Liberty Grove townhouses. Realistic budget $300K–$900K for thoughtful 60–130m² addition; $700K–$1.8M premium river-fall heritage-grade work.
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.
Home extension 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
- $150,000 – $600,000+
- Typical timeline
- 6–12 months design to handover
- Approval pathway
- CDC for most rear extensions, DA for second-storey
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 extension, 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 extension, 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 Extension
Cost breakdown for a typical extension 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 home extension, 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 Extensions in Mortlake reveal a clear pattern — applications with proper structural engineering tied to the existing footings on Class M–H (Wianamatta Shale) / H (river/bay fall) soil and clean shadow analysis to neighbours' POS are progressing without RFIs. Sloppy lodgement adds 4-8 weeks of round-trip; clean lodgement doesn't.
Builder's Take on Mortlake
Timing on Mortlake extensions typically runs 14–24 weeks for ground-floor additions, 20–32 weeks for second-storey. Living in the house during the build is possible but requires staging — we plan around it so the kitchen and main bathroom aren't out at the same time.
Matching brick on a Mortlake extension: 1900s–1960s brick is often discontinued. We specify a close-match or deliberately contrast with render or cladding so the extension reads as intentional, not as a failed match. Done well, an intentional contrast looks better than a forced match.
Mortlake vs Nearby Suburbs
Mortlake vs nearby suburbs — key metrics for extending.
| Suburb | Median Price | Typical Lot | Soil Class | Era | Station |
|---|---|---|---|---|---|
| Mortlake2137this suburb | $1.9M–$3.5M | 400–800m² | Class M–H (Wianamatta Shale) / H (river/bay fall) | 1900s–1960s | North Strathfield (2 km) / Mortlake ferry to Putney |
| Cabarita2137 | $2.5M–$5M | 500–1,000m² | Class M–H (Wianamatta Shale) / H (river/bay fall) | 1900s–1940s | North Strathfield (2 km) |
| Breakfast Point2137 | $2.0M–$4M | 200–500m² | Class M–H (Wianamatta Shale) / H (river/bay fall) | 2000s+ master-planned | North Strathfield (3 km) |
| Concord2137 | $2.2M–$4M | 500–900m² | Class M–H (Wianamatta Shale) / H (river/bay fall) | 1900s–1960s | 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.
Have a question about your project?
Talk to our team — free site assessment and fixed-price quote.
How It Works
From First Call to Final Key
We assess your Mortlake home — existing structure, block size (400–800m²), R2 Low / R3 Medium / R4 (Rhodes/Concord West) zoning, setbacks, FSR, and your space requirements. You'll know what's achievable before spending on detailed design.
⏱Design phase covers the extension layout, junction with existing structure, window and door placement, and external finish to match your Mortlake home's streetscape. Multiple design options presented.
⏱Documentation pack covers structural engineering for the new footings sized to match existing depths on Class M–H (Wianamatta Shale) / H (river/bay fall) soil, BASIX 2025 compliance, shadow diagrams to neighbours' POS, hydraulic, and detailed sections through the wall-tie junction. Approval-grade, not concept-grade.
⏱Fixed-price construction of your extension. New footings engineered for Class M–H (Wianamatta Shale) / H (river/bay fall) soil, structural connection to existing home, frame, fit-out, and finishes.
⏱Handover documentation covers the new work specifically — OC for the extension, structural certs, BASIX certificate updates, and warranty for the new section plus the junction detailing. Existing house remains under whatever warranty position applied before.
⏱Quality Promise
Buildana's Mortlake home extension process: assess the existing structure, design the addition, approve, build. Fixed price throughout.
Cost Guide
| Item | Estimated Range |
|---|---|
| Adding a master suite (1900s–1960s Mortlake home) | $120,000 – $270,000 |
| Kitchen/living open-out to backyard | $140,000 – $330,000 |
| Second storey for teenagers/office | $270,000 – $520,000 |
| Extension + bathroom (growing family) | $190,000 – $380,000 |
| Full rear + roof tie-in (entertainer's zone) | $330,000 – $570,000 |
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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Last updated: 1 April 2026
Extend, Don't Move — Mortlake
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