Mosman Home Extension Builder — Live In, Build On
Buildana extends homes across Mosman 2088 while you stay in place. 1880s–1940s heritage-era structure, Mosman Council rules, weatherproofing during build — all managed locally from Fairfield.
HIA Member
MBA NSW0476 300 300Extending Homes in Mosman
A home extension in Mosman is premium heritage work, and the market here is unforgiving about it. The homes are 1880s to 1940s on 500 to 1,000m² blocks, and a $4.5M to $8.0M postcode expects the wing to be built behind the conserved fabric to an exacting standard — anything that looks like a compromise stands out and costs you at resale.
So the heritage position leads every decision and is mapped before a line is drawn. Where the blocks drop away the sandstone falls are engineered properly, and the oldest fabric gets licensed lead and asbestos handling throughout.
With the village, the schools and the harbour all on the line, extending beats leaving every time — you keep the lot and simply build the house up to the standard the address already implies.
We build these fixed-price, licence HBL 487805C. Get our extension scope, with the heritage position mapped, before you commit.
Buildana manages the complete home extension process in Mosman — 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 Mosman from $150K
- Mosman Council DA and CDC approvals managed
- Ground floor, rear and second-storey additions
- M — structural engineering included
- 1880s–1940s heritage-era homes assessed for extension suitability
- Connect new to existing — clean, matched finish
- 6-year structural warranty
- Free design consultation — near North Sydney (4 km, ferry from Mosman Bay) station
Reviewed by Oliver Alameri
Licensed Builder (NSW 487805C) · Master of Property Development · PhD Student · Building across Western Sydney since 2010
Exact, or it costs you
Mosman's market pays for heritage-respecting wings done exactly and punishes anything less — so the addition builds behind the conserved fabric, finished to the standard the postcode enforces.
The 500 to 1,000m² blocks give the design genuine room to do it properly.
Heritage, fall and fabric
The heritage position is mapped before design, and the sandstone falls are engineered where the blocks drop.
Lead paint and asbestos both go through the licensed processes, and all of it is priced into the job from the outset.
Home extension builder in Mosman — key facts
- Suburb
- Mosman, NSW 2088
- Council / LGA
- Mosman Council (Mosman)
- Primary zoning
- R2 Low Density
- Typical lot size
- 500–1,000m²
- Soil class
- M
- Median house price
- $4.5M–$8.0M
- Home era
- 1880s–1940s heritage
- 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.
Quality Promise
Mosman home extension specialists: we work on your home while you live in it, weatherproof the site nightly, finish clean.
How It Works
From First Call to Final Key
Walk through your Mosman home with our designer and structural engineer. We measure, photograph, and check the bones — footings, frame condition, roof structure. The cost estimate that follows is grounded in what we found, not a generic per-m² number.
⏱Our designer works with your existing home's layout — connecting new living areas to existing rooms, matching materials and roof pitch, and maximising natural light. You approve floor plans and 3D renders before we proceed.
⏱Most rear extensions in Mosman qualify for CDC — cleaner, faster, no neighbour notification. Second-storey additions typically need DA through Mosman Council because of overshadowing and privacy assessments. We choose based on your design, not on what's easier to lodge.
⏱Extension built from new footings to completion — connecting structurally to your existing home. Class M soil design managed. Temporary weatherproofing maintains liveability where possible.
⏱Walk through the completed extension, confirm finishes, collect your OC. Six-year structural warranty covers all new work including the junction with your existing home. Maintenance guide provided.
⏱Our Team
Oliver Alameri
Founder / Director / Builder · MPropDev · PhD Student
Ahmad Alameri
Accounts Manager
Claire Wendell
Project Manager
Estimate Your Build Cost
Use our free calculator to get an instant cost estimate for your project
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.
Frequently Asked Questions
Buildana built our granny flat in just 12 weeks. Fast approvals, great communication, and a beautiful final product. Highly recommend.
Fatima Al-Rashid
Liverpool, NSW
We Build Across Sydney
Headquartered in Western Sydney's Fairfield. Active across all 28 metropolitan Sydney LGAs — from Penrith to the Eastern Suburbs, the Hills to the Sutherland Shire.
Last updated: 1 April 2026
Add Space to Your Mosman Home
Free design consultation for Mosman 2088. We'll assess your home, design the extension, and provide a fixed-price quote.
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Other Buildana services in Mosman
Costs, approval pathway and fixed-price contract detail for every other build type we deliver in Mosman 2088. Mosman Council regulations and local controls are covered on each page.