AUD Build

DUPLEX BUILD COST SYDNEY · 2026 GUIDE

Duplex build cost in Sydney (2026): what two homes on one block really cost

Sydney duplex costs 2026: A$700k–A$1.8m to build both homes before land, A$2,200–A$4,500/m², plus demolition, council charges, HBC and subdivision.

Read the breakdown ↓Ask AUD Build

Published by AUD Build · Figures reviewed 26 October 2026

Short answer

Short answer (as of October 2026): published Sydney cost guides put the construction of a duplex — both dwellings, excluding land — at roughly A$700,000 to A$1.8 million, or about A$2,200–A$4,500 per square metre of total floor area, with architectural and luxury duplexes running higher. Once demolition, approvals, council and state contributions and external works are added, all-in budgets for a typical 2 × 150 m² knockdown duplex are quoted at about A$0.9–1.35 million in Western Sydney and A$1.5–1.8 million in premium council areas such as Ku-ring-gai, before land and any Torrens subdivision.

These are budgeting ranges taken from the dated sources listed at the end of this page, not a quote. Your block, council area, floor area and specification decide where you land.

What the 2026 guides say

Scenario (both dwellings, excluding land)Published rangeSource
Standard or project duplex, construction onlyA$1.0m–1.3m (A$2,500–3,200/m²)Provincial Homes [3]
Mid-range architectural, construction onlyA$1.3m–1.8m (A$3,200–4,000/m²)Provincial Homes [3]
Luxury or custom, construction onlyA$1.8m–2.5m+ (A$4,000–5,000+/m²)Provincial Homes [3]
2 × 150 m² attached, medium brick veneer, constructionA$700k–1.1mgiantA [4]
Standard Sydney duplex, constructionA$800k–1.6m+ (A$2,400–3,800+/m²)MNA Construction [5]
NSW duplex, build onlyA$700k–1.2m (A$2,500–4,500/m²)The Quote Yard [7]
400 m² duplex (2 × 200 m²), build onlyA$1.4m–2.4m (A$3,200–4,500/m² standard; A$4,500–6,500/m² premium)CPP Quantity Surveyors [8]
All-in, 2 × 150 m², medium brick veneer, Western Sydney (includes demolition, external works, council fees)A$885k–1.025mBuildana, May 2026 refresh [1]
All-in, medium spec 2 × 150 m², Western SydneyA$900k–1.35mgiantA [4]
All-in, same spec in Ku-ring-gai, Woollahra or Canada BayA$1.5m–1.8mgiantA [4]

Per-square-metre benchmarks from a Western Sydney builder using Rawlinson-based rates (May 2026): medium brick veneer A$2,295–2,475, medium full brick A$2,385–2,565, high-spec brick veneer A$3,215–3,465, high-spec full brick A$3,275–3,525 [1][2]. A Hills and North Shore builder quotes A$3,400–5,000/m² for dual occupancy [6].

Why the numbers differ so much

  • Location. The lowest per-m² figures come from Western Sydney builders on flat blocks [1][2]. North Shore builders and a quantity-surveying firm quote materially higher rates [6][8]. One North Shore builder says build costs in inner north shore councils run 10–20% above Hills District equivalents [6].
  • What "floor area" means. Some quotes include garages, alfresco and porticos in the rate; others count internal living area only. A rate that looks A$300/m² cheaper may not be [3].
  • Builder price vs QS benchmark. CPP QS publishes quantity-surveyor estimates; most other sources are builders describing their own pricing.
  • Recycled data. giantA's cost table cites Rawlinson and Buildana project records, so those two sources are not independent [4].
  • Internal inconsistency. Provincial Homes' tier table (A$1.0–1.3m for a standard duplex) sits above its own worked example (2 × 150 m² quality duplex at A$850k–1.0m) [3].

The full cost breakdown

A construction price covers the building. Ask every builder which of the items below are included, excluded or carried as provisional sums.

Cost itemTypical published rangeNotes and source
Demolition of the existing houseA$10k–50kBuildana A$10–20k [1]; giantA A$20–40k [4]; MNA A$25–45k+ [5]; Provincial A$25–50k [3]
Asbestos removalA$5k–25k[1][3]. A licensed removalist is required for friable asbestos and for more than 10 m² of bonded asbestos [23]
Detail survey and geotechnical reportA$3.5k–8kProvincial A$2–4k + A$1.5–3k [3]; Buildana A$5–8k [1]
Architectural design and documentationA$8k–50kProvincial A$8–25k [3]; giantA A$10–20k per dwelling [4]; Pearson A$25–50k [6]
Structural engineeringA$3k–6k[3]
BASIX and NatHERS assessmentA$1k–3k[3]. BASIX standards rose to 7-star NatHERS thermal performance from 1 October 2023 [22]; giantA estimates the upgrade at A$10–30k per duplex versus pre-2023 designs [4]
DA or CDC (fees and consultants)DA A$5k–15k; CDC certifier A$2k–5k[1][3][4]. The council DA application fee itself is a maximum of about A$2,750–4,780 for an estimated cost of A$0.7–1.8m (DPHI 2026/27 schedule, item 2.1), before notification fees and reports [16]
Local council contributions (s7.11 or s7.12)Builders quote A$18k–55k per dwelling[1][3][4]. Official position: most s7.11 plans can charge up to A$20,000 or A$30,000 per lot or dwelling unless IPART has reviewed a higher rate; s7.12 levies are usually no more than 1% of cost [15]
Housing and Productivity Contribution (state)About A$10,800 per net new dwelling (Greater Sydney)Dual occupancy is treated as medium-density; replacing one house with a duplex adds one net dwelling [14]. Rate A$10,812.18 as indexed on 1 January 2026, adjusted quarterly [13]
Sydney Water infrastructure contributionAbout A$2,950 in Sydney Water's worked exampleExample: one house replaced by an attached dual occupancy on 650 m²; full prices apply from 1 July 2026 and vary by area [17]. Dual occupancies need a Section 73 certificate [18]
Long service levy0.25% of cost (A$2,500 per A$1m)Applies to work of A$250,000 or more including GST; the CC or CDC is only released after payment [19]
Home Building Compensation (HBC) insuranceAbout 1.16% of contract value (metro base)icare metro base rate for new dwellings 1.158% including GST and stamp duty, before each builder's loading or discount [20]; compulsory over A$20,000 [21]
Engineered footings on reactive clayA$12k–22k per dwelling[1][3]
Sloping site (cut and fill, retaining)A$40k–90k per duplex[3]
On-site stormwater detentionA$10k–25k[4]
Service connections for the second dwellingA$5k–15k per dwelling[4]
External works (driveway, fencing, landscaping)A$30k–60k per dwelling[1][3]
Torrens title subdivision (optional)A$15k–60kgiantA A$15–25k plus council fees [4]; CPP QS A$15–30k [8]; Buildana and Provincial A$30–60k [1][3]
Contingency5–15%Provincial 8–12% [3]; CPP QS 5–15% [9]

Charges most guides leave out. None of the builder guides we reviewed itemises the state Housing and Productivity Contribution or the long service levy, and only one mentions Sydney Water, inside its subdivision allowance [1]. On a typical knockdown duplex these three add roughly A$16,000–A$18,000 at a A$1–1.8 million build cost (our arithmetic from [13][17][19]).

Council contributions are where sources disagree most. Builders report A$18,000–A$55,000 per dwelling [1][3][4]; the Department's guide says most s7.11 plans are capped at A$20,000 or A$30,000 per lot or dwelling unless IPART-reviewed [15]. Ask your council or certifier for the contributions plan that applies to your address before you rely on any figure.

Does your block suit a duplex?

  • Dual occupancies are permitted with consent in R2 zones state-wide [10].
  • A CDC (complying development certificate, a fast-track combined planning and construction approval) for a duplex is only available in R1, R2, R3 and RU5 zones where the council's LEP already allows dual occupancy. The lot must meet the LEP minimum lot size, or 400 m² if the LEP sets none, and CDCs are excluded on heritage items, heritage conservation areas and other excluded land [12]. A complying CDC can be issued within 20 days [11][12].
  • Within Low and Mid-Rise Housing areas (residential land within 800 m walking distance of nominated stations and town centres), non-refusal standards for dual occupancies include a 0.65:1 floor space ratio, 9.5 m height, one parking space per dwelling and 225 m² per lot for subdivision [10].
  • Builders disagree on how many duplexes qualify for a CDC; giantA estimates 20–30% of Western Sydney duplex projects [4].

Allow roughly 12–24 months from design to handover; published construction phases run 8–14 months [3][7]. See our knockdown rebuild timeline guide for stage-by-stage weeks.

Where AUD Build fits

AUD Build is the Sydney residential construction brand operated by Australian Urban Direct iBuying Pty Ltd (ABN 62 617 159 369). Its NSW contractor licence 475778C is in the Builder class, current from 18 March 2025 to 17 March 2029, with no compliance, enforcement or disciplinary record shown on Verify NSW when checked on 26 October 2026 [26].

  • Design and approval: AUD Design's DA/CDC design and application service is A$9,999 + GST (A$10,998.90 including GST). Eligibility, scope, revisions and deliverables are confirmed in a written quotation; third-party reports are excluded, and any government, certifier or consultant charges are itemised in writing. The fee is not an approval guarantee or a construction price.
  • Cost planning during design: construction cost is estimated alongside the design, so shared-site works and each dwelling's specification are priced before lodgement.
  • English and Chinese communication throughout the project.
  • AUD Build construction pricing: quoted per project in writing after reviewing the site and the design; AUD Build does not publish a fixed duplex price.
  • What the quote shows: inclusions, exclusions, provisional sums, material specifications, programme assumptions and the written variation process, so demolition, asbestos, external works, connections, HBC insurance, the long service levy and government charges are each listed as included or excluded.
  • Construction period: set out in the written quote and the building contract for each project.

As of 20 October 2026, AUD Group building companies report 21 homes completed since September 2024 and 10+ residential projects in construction across Sydney. These are group figures across AUD Group building companies, not figures for AUD Build or licence 475778C alone.

Send your address and plans to AUD Build · Duplex builder Sydney service

Send my site to AUD Build →

How to verify a builder before you sign

  1. Check the licence. Search the contracting company on Verify NSW or through Service NSW's licence check [25]. Confirm the licence holder matches the company on your contract, the class covers the work, and the record shows no conditions or disciplinary action. AUD Build's record: Verify NSW, licence 475778C.
  2. Check HBC cover before paying anything. For home building work over A$20,000, check the business has valid HBC cover before you pay any money, including the deposit [21]. Use the official HBC Check.
  3. Check the contract. Work over A$20,000 needs a large job contract with a five-clear-business-day cooling-off statement; the deposit must not exceed 10%, and progress payments should match work actually done [24].
  4. Review public evidence. AUD Build's third-party evidence page links its licence record, HBC certificates and planning records.

Frequently asked questions

How much does it cost to build a duplex in Sydney in 2026?

Published guides put construction of both dwellings at about A$700,000–A$1.8 million before land, with luxury builds above A$1.8 million. All-in budgets for a typical 2 × 150 m² knockdown duplex are quoted at A$0.9–1.35 million in Western Sydney and A$1.5–1.8 million in premium council areas, excluding land and subdivision.

What is the duplex build cost per square metre in Sydney?

Most 2026 guides quote about A$2,200–A$4,500 per m² across both dwellings. Western Sydney builders quote A$2,295–A$3,525 for medium to high specification, while North Shore builders and a quantity surveyor quote A$3,200–A$6,500 depending on finish.

What government charges apply to a new duplex in NSW?

Expect council contributions (s7.11 or s7.12), the state Housing and Productivity Contribution (about A$10,800 per net new dwelling in Greater Sydney), a Sydney Water infrastructure contribution and Section 73 certificate, the 0.25% long service levy, DA or CDC fees, and HBC insurance through the builder.

Is Torrens title subdivision included in the build price?

Usually not. Published estimates range from A$15,000 to A$60,000 for survey, legal, council and registration costs, and lots must meet the council's minimum lot size.

Is a CDC cheaper and faster than a DA for a duplex?

Where a site complies with every standard, a CDC can be issued within 20 days and certifier fees are usually lower than DA costs. Many duplex sites need a DA because of lot size, heritage or other constraints.

Does AUD Build publish a duplex price?

AUD Design's DA/CDC design and application service is A$9,999 + GST, subject to a written quotation. AUD Build's construction pricing is provided per project after reviewing the site and design. AUD Build does not publish a fixed duplex price.

YOUR SITE · YOUR PLANS · A WRITTEN QUOTE

Get a quote built from your own site and plans.

Send your address, plans or brief. We will review the site and design before quoting.

Send my site to AUD Build →

Sources (all read 26 October 2026)

  1. Buildana, "Duplex Build Cost Sydney — Complete 2026 Price Guide", published 14 Apr 2026, updated Sep 2026 — https://www.buildana.com.au/insights/duplex-build-cost-sydney
  2. Buildana, "Duplex Cost Per m² Sydney 2026", published 13 Apr 2026 — https://www.buildana.com.au/insights/duplex-cost-per-sqm
  3. Provincial Homes, "The Ultimate Guide To Building A Duplex In Sydney", updated 26 Aug 2026 — https://www.provincialhomes.com.au/the-cost-of-building-a-duplex-in-sydney/
  4. giantA, "Duplex Construction Cost Sydney 2026", published 23 Jul 2026, modified 30 Sep 2026 — https://www.gianta.com.au/blog/build-11/duplex-construction-cost-sydney-2026-complete-cost-guide-approval-pathways-zoning-requirements-70
  5. MNA Construction, "Duplex Development in Sydney: Is Your Block Suitable for Dual Occupancy?", 11 Aug 2026 — https://www.mnaconstruction.com.au/blog/duplex-feasibility-sydney/
  6. Pearson Industries, "Dual Occupancy Sydney: Costs, Approvals & What to Expect in 2026", 13 May 2026 — https://pearsonindustries.com.au/extensions/dual-occupancy-sydney-costs-approvals-guide/
  7. The Quote Yard, "Duplex Builders NSW" (no date shown) — https://www.thequoteyard.com.au/services/duplex-builders-nsw
  8. CPP Quantity Surveyors, "Cost to Build a House in Sydney: A 2026 Guide", 11 Jun 2026 — https://www.cppqs.com.au/post/cost-to-build-a-house-in-sydney-a-2026-guide
  9. CPP Quantity Surveyors, "NSW Construction Cost Update – Residential Homes (2026)", 29 May 2026 — https://www.cppqs.com.au/post/nsw-construction-cost-update-residential-homes-2026
  10. NSW Department of Planning, Housing and Infrastructure (DPHI), Low and Mid-Rise Housing Policy — summary of key provisions — https://www.planning.nsw.gov.au/the-planning-system/housing/low-and-mid-rise-housing-policy/summary-of-key-provisions
  11. DPHI, Complying development — https://www.planning.nsw.gov.au/the-planning-system/development-assessment/planning-approval-pathways/complying-development
  12. NSW Planning Portal, Low Rise Housing Diversity Code — https://www.planningportal.nsw.gov.au/development-and-assessment/codes-sepp/low-rise-housing-diversity-code
  13. NSW Planning Portal, Housing and Productivity Contribution (indexed rates as of 1 Jan 2026) — https://www.planningportal.nsw.gov.au/development-and-assessment/contributions/housing-and-productivity-contribution
  14. DPHI, Housing and Productivity Contribution — Applicant Guide to Dual Occupancies, Dec 2025 — https://planning.nsw.gov.au/sites/default/files/2025-12/applicant-guide-to-dual-occupancies.pdf
  15. DPHI, Guide to infrastructure contributions (2025) — https://www.planning.nsw.gov.au/sites/default/files/2025-05/guide-to-infrastructure-contributions.pdf
  16. DPHI, Schedule of planning and development fees and charges 2026/27 — https://www.planning.nsw.gov.au/sites/default/files/2026-06/schedule-planning-development-fees-charges-2026-27.pdf
  17. Sydney Water, Infrastructure contributions — how to calculate your charge (worked examples), 23 Feb 2026 — https://sydneywater.com.au/content/dam/sydneywater/documents/infrastructure-contributions-worked-examples.pdf
  18. Sydney Water, Types of development that need a Section 73 certificate — https://www.sydneywater.com.au/content/dam/sydneywater/documents/types-of-development-that-need-a-section-73-certificate.pdf
  19. NSW Government (Long Service Corporation), Long service levy, modified 15 Jun 2026 — https://www.nsw.gov.au/employment/rights-responsibilities/portable-long-service/bci-long-service-payments-scheme/long-service-levy
  20. icare, HBCF premium guidelines (rates effective 1 Nov 2025) — https://www.icare.nsw.gov.au/builders-and-homeowners/builders-and-distributors/premiums/premium-rates
  21. NSW Government, Insurance cover for building work, modified 6 Jul 2026 — https://www.nsw.gov.au/business-and-economy/licences-and-credentials/building-and-trade-licences-and-registrations/insurance-cover
  22. NSW Planning Portal, BASIX standards — https://www.planningportal.nsw.gov.au/BASIX-standards
  23. SafeWork NSW, Asbestos, modified 14 Aug 2026 — https://www.safework.nsw.gov.au/hazards-a-z/asbestos
  24. NSW Government, Contracts for building or renovating — https://www.nsw.gov.au/housing-and-construction/building-or-renovating-a-home/preparing/contracts
  25. Service NSW, Check a builder or tradesperson licence — https://www.service.nsw.gov.au/transaction/check-a-builder-or-tradesperson-licence
  26. Verify NSW, Contractor Licence 475778C (checked 26 Oct 2026) — https://verify.licence.nsw.gov.au/details/Contractor%20Licence/1-49ETYNF ; HBC Check — https://verify.licence.nsw.gov.au/home/HBCF
  27. AUD Build, Third-party evidence — https://audbuild.com/insights/third-party-evidence/

Published by AUD Build, which also offers duplex construction services. Market figures are third-party estimates for budgeting; they are not AUD Build prices.

Related guides: Knockdown rebuild cost in Sydney (2026): the full breakdown · How long does a knockdown rebuild take in Sydney? CDC vs DA, stage by stage (2026)