Home Extension Builder Chatswood — From $150K Fixed Price
Fixed-price home extensions in Chatswood 2067. Rear extension $150K–$300K, second storey $300K–$500K. Willoughby City Council approvals managed. Free site consult.
HIA Member
MBA NSW0476 300 300Quick Answer
A home extension in Chatswood costs $150,000–$600,000+. Rear extension from $150K, second-storey addition from $300K. Buildana manages design, Willoughby City Council approvals, and construction under one fixed-price contract.
Second-Storey & Rear Additions in Chatswood
A home extension in Chatswood splits by which side of the Pacific Highway you are on. East of the highway, the Federation and Californian Bungalow stock is solid double brick that carries a first-floor addition on its original walls. On the western flats, the post-war homes are better grown outward at ground level. Same suburb, two methods, and knowing which you own is the first question.
The land argument is strong either way. The Sydney Metro and T1 North Shore both stop here, and detached houses on the 500 to 800m² blocks are increasingly rare against the apartment towers, so at a $2.6M to $3.8M median extending holds something the precinct barely makes anymore. R3 zoning along the Help Street corridor adds duplex and townhouse options on the right block.
What I would check first on your Chatswood house: whether it is eastern double brick or western post-war, and whether an R3 Help Street pocket changes the options. Those decide up or out.
We build these fixed-price, licence HBL 487805C. Get us to read your walls and your zoning first.
Buildana manages the complete home extension process in Chatswood — 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 Chatswood from $150K
- Willoughby City Council DA and CDC approvals managed
- Ground floor, rear and second-storey additions
- M — structural engineering included
- 1920s–1970s (Federation, inter-war, mid-century)-era homes assessed for extension suitability
- Connect new to existing — clean, matched finish
- 6-year structural warranty
- Free design consultation — near Chatswood station
Reviewed by Oliver Alameri
Licensed Builder (NSW 487805C) · Master of Property Development · PhD Student · Building across Western Sydney since 2010
Which side of the highway
East of the Pacific Highway, the Federation and Californian Bungalow stock is solid double brick that carries a first-floor addition on its original walls. On the western flats, post-war homes do better added across the ground.
Same suburb, two methods, and knowing which you own is the first question we answer.
Metro-rated land
The Sydney Metro and T1 North Shore both stop here, and detached houses on the 500 to 800m² blocks are increasingly rare against the towers. At a $2.6M to $3.8M median, extending holds something the precinct barely makes anymore.
R3 zoning down the Help Street corridor opens duplex and townhouse options on the right block.
Home extension builder in Chatswood — key facts
- Suburb
- Chatswood, NSW 2067
- Council / LGA
- Willoughby City Council (Willoughby)
- Primary zoning
- R2
- Typical lot size
- 500–800m²
- Soil class
- M
- Median house price
- $2.6M–$3.8M
- Home era
- 1920s–1970s
- 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
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
Everything that has to be right before we touch the ground. We assess your Chatswood home — existing structure, block size (500–800m²), R2 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 Chatswood home's streetscape. Multiple design options presented.
⏱The Chatswood construction phase. Fixed price, programmed, supervised. Documentation pack covers structural engineering for the new footings sized to match existing depths on Class M 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 soil, structural connection to existing home, frame, fit-out, and finishes. Weekly updates from your project manager.
⏱The job isn't done when the site's clean; it's done when you have keys, certificates and warranties. 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
Every Buildana home extension in Chatswood is delivered under a fixed-price contract — from design consultation through to defect-free handover.
Cost Guide
| Item | Estimated Range |
|---|---|
| Small rear extension (up to 30m²) | $108,000 – $220,000 |
| Medium rear/side extension (30–60m²) | $220,000 – $380,000 |
| Large ground-floor extension (60–100m²) | $380,000 – $600,000 |
| Second-storey addition (60–120m²) | $340,000 – $660,000 |
| Wrap-around (ground + 1st floor) | $600,000+ |
| Structural engineering & tie-in | 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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Frequently Asked Questions
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Fatima Al-Rashid
Liverpool, NSW
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Last updated: 1 April 2026
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Costs, approval pathway and fixed-price contract detail for every other build type we deliver in Chatswood 2067. Willoughby City Council regulations and local controls are covered on each page.