Licensed Home Extension Builder Box Hill
NSW licensed extension specialist. Box Hill 2765 extensions on 2015+ contemporary-era homes require structural sign-off, Class M footings, and matched connection — we engineer and document properly.
HIA Member
MBA NSW0476 300 300Quick Answer
A home extension in Box Hill costs $150,000–$600,000+. Rear extension from $150K, second-storey addition from $300K. Buildana manages design, The Hills Shire Council approvals, and construction under one fixed-price contract.
Box Hill Home Extensions — Fixed Price
A home extension in Box Hill gets a straight answer — most of this 2015+ new-release stock is too young to extend, and I will say so rather than take the job.
Where the family has genuinely outgrown the plan, the 300 to 600m² blocks take a designed-to-the-metre rear addition, with the estate guidelines and the clay junctions both handled.
At the $1.1M to $1.6M range, the targeted wing can still beat the cost of trading up within the release.
We build these fixed-price, licence HBL 487805C. Tell me what you are chasing and I will give you the honest read.
Buildana manages the complete home extension process in Box Hill — 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 Box Hill from $150K
- The Hills Shire Council DA and CDC approvals managed
- Ground floor, rear and second-storey additions
- M — structural engineering included
- 2015+ contemporary-era homes assessed for extension suitability
- Connect new to existing — clean, matched finish
- 6-year structural warranty
- Free design consultation — near Bus to Rouse Hill Metro (5 km) station
Reviewed by Oliver Alameri
Licensed Builder (NSW 487805C) · Master of Property Development · PhD Student · Building across Western Sydney since 2010
The honest read comes first
Box Hill's homes are mostly under ten years old — extending them rarely stacks up yet, and I say that upfront rather than invoice you to learn it.
The exception is the genuinely outgrown plan: a young family that bought small and needs the extra room now.
When it does stack up
The compact blocks take precise rear additions — designed to the metre, estate guidelines checked, clay junctions engineered.
Fixed against a measured scope, so the number holds from quote to handover.
Home extension builder in Box Hill — key facts
- Suburb
- Box Hill, NSW 2765
- Council / LGA
- The Hills Shire Council (The Hills)
- Primary zoning
- R2 Low
- Typical lot size
- 300–600m² (new release)
- Soil class
- M
- Median house price
- $1.1M–$1.6M (new release)
- Home era
- 2015+ contemporary
- 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.
Cost Guide
| Item | Estimated Range |
|---|---|
| Single-room addition (bedroom/study) | $57,000 – $130,000 |
| Kitchen/living extension | $140,000 – $330,000 |
| Master suite + ensuite addition | $120,000 – $270,000 |
| Second storey (full or partial) | $270,000 – $520,000 |
| Multi-room ground floor wrap | $330,000 – $570,000 |
Prices are indicative for Western Sydney (2025). Actual costs depend on site, specifications, and approvals.
How It Works
From First Call to Final Key
On-site assessment of your 2015+ contemporary-era home in Box Hill. We check structural condition, block dimensions (300–600m² (new release)), setback availability, and The Hills Shire Council's DCP requirements. Written feasibility and cost estimate provided.
⏱Designing an extension is half about the new space and half about how it joins the old one. Doorway position, ceiling height transition, floor level matching, light wells — the junction makes or breaks how the finished home feels.
⏱We lodge your extension approval — CDC for eligible designs or DA through The Hills Shire Council. Full documentation including structural engineering for Class M soil, BASIX, and shadow diagrams. CC issued before works start.
⏱For ground-floor rear extensions you usually stay in the house during the build, with temporary weatherproofing at the junction wall until the new section is locked up. Second-storey additions need a 4–8 week relocation during the roof-off and frame-up phase.
⏱Final inspection, Occupation Certificate, 6-year structural warranty. Your Box Hill home now has the space your family needs.
⏱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.
Add Space to Your Box Hill Home
Free design consultation for Box Hill 2765. We'll assess your home, design the extension, and provide a fixed-price quote.
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Other Buildana services in Box Hill
Costs, approval pathway and fixed-price contract detail for every other build type we deliver in Box Hill 2765. The Hills Shire Council regulations and local controls are covered on each page.