Mount Colah Granny Flat Builder — Local, Fixed-Price
Buildana builds granny flats across Mount Colah 2079 from our Fairfield office. Typical Mount Colah rental yield: $520–$720/week (Hornsby Hospital + Hornsby TAFE + Macquarie University proximity). Free site assessment.
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MBA NSW0476 300 300Quick Answer
A granny flat in Mount Colah costs $150,000–$300,000+ depending on size and finishes. 1-bed from $150K, 2-bed from $200K. CDC fast-track approval in 10–15 business days. Buildana manages design, Hornsby Shire Council approval and fixed-price construction.
Building Granny Flats in Mount Colah
Mount Colah is a bushland-fringe suburb north of Asquith — 1960s to 1990s brick on generous 700 to 1,000m² blocks, many backing onto Berowra Valley National Park. The blocks are big, so a granny flat has room; the two things that shape the build are the bushfire rating and the sandstone.
Most blocks here carry a BAL rating — commonly BAL-12.5 to BAL-29, up to Flame Zone on the direct bushland edge — so a second dwelling has to be designed to the RFS requirements for its rating. That's normal for this pocket, just factored in from the start.
The Hawkesbury Sandstone means rock excavation is common, usually $30,000 to $120,000 above standard. I get a geotech bore and the bushfire assessment before I quote so both are in the number.
Fixed price with the bushfire and rock both sorted first. Licence HBL 487805C.
Buildana manages the full granny flat process in Mount Colah — from site assessment and CDC fast-track approval through to fixed-price construction and handover. We build studio, 1-bedroom, and 2-bedroom designs up to the NSW maximum of 60m².
Read our Complete Granny Flat Guide or explore granny flat builds across Sydney.
- Granny flats in Mount Colah from $150K
- CDC fast-track approval (10–15 business days)
- 700–1,000m² blocks — most qualify for 60m² granny flat
- Mount Colah zoned R2 Low Density predominant / R3 Medium Density on Hornsby/Asquith/Waitara/Pennant Hills station precincts / R4 (Hornsby CBD high-rise zone) / RU2 Rural Landscape (Galston/Berrilee/Arcadia/Forest Glen/Glenorie acreage belt)
- Fixed-price contract — design to handover
- Hawkesbury Sandstone bedrock — engineered slab included
- Rental yield $520–$720/week (Hornsby Hospital + Hornsby TAFE + Macquarie University proximity) in Mount Colah
- Free site assessment — near Mount Colah station
Reviewed by Oliver Alameri
Licensed Builder (NSW 487805C) · Master of Property Development · PhD Student · Building across Western Sydney since 2010
Room to build, bushfire to design for
Mount Colah's 700 to 1,000m² blocks give plenty of room for a proper second dwelling. The catch, and it's a real one, is that most of the suburb backs onto Berowra Valley National Park, so there's a bushfire rating to meet.
Usually that's BAL-12.5 to BAL-29 — manageable, with the right cladding, glazing and screening — up to Flame Zone on the direct bush edge. I get the bushfire assessment upfront so the design meets the RFS requirements from the start, not as an afterthought.
Sandstone rock, tested
The Hawkesbury Sandstone means rock excavation is common — usually $30,000 to $120,000 above a standard substructure — so I get a geotech bore and put the rock in the fixed price rather than hitting it mid-build.
Between the bushfire and the rock, this is a suburb where the upfront testing genuinely matters. Get both right and the fixed price holds.
Granny flat builder in Mount Colah — key facts
- Suburb
- Mount Colah, NSW 2079
- Council / LGA
- Hornsby Shire Council (Hornsby Shire)
- Primary zoning
- R2 Low Density predominant
- Typical lot size
- 700–1,000m²
- Soil class
- Hawkesbury Sandstone bedrock
- Median house price
- $1.8M–$2.6M Hornsby/Asquith/Mount Colah; $2.4M–$3.6M Cherrybrook/Beecroft/Pennant Hills; $3.0M–$8.0M+ Galston/Arcadia acreage
- Home era
- 1900s–1940s Federation heritage
- Typical price range
- $150,000 – $300,000+
- Typical timeline
- 4–6 months design to handover
- Approval pathway
- CDC via NSW Affordable Rental Housing SEPP (10–15 days)
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 |
|---|---|
| Attached granny flat | $160,000 – $220,000 |
| Detached granny flat | $190,000 – $260,000 |
| Above-garage granny flat | $230,000 – $300,000 |
| Premium detached (upgraded finishes) | $260,000 – $320,000 |
Prices are indicative for Western Sydney (2025). Actual costs depend on site, specifications, and approvals.
How It Works
From First Call to Final Key
Most Mount Colah blocks support a granny flat — the question is where it sits, how it accesses the street, and how it shares the yard with the main house. We work that out on site, with the existing house and existing services in front of us.
⏱1-bed or 2-bed floor plan designed for your Mount Colah block — up to the NSW maximum of 60m². Layout, window placement, kitchen and bathroom positioning optimised for liveability and rental appeal.
⏱We lodge your CDC application with all required documentation — BASIX, plans, site analysis, stormwater. Private certifier approval in 10–15 business days. CC issued and you're ready to build.
⏱12-week typical timeline for a 60m² 2-bed: slab pour week 1, frame stand weeks 2–3, lock-up week 5, internal fit-out weeks 6–10, finishes and external works weeks 11–12. We provide the dated programme upfront so you can plan move-in or tenant placement.
⏱OC issued, defect-free inspection completed, keys handed over. Your granny flat is ready to occupy or lease. Well-finished 2-bed units near Mount Colah station are achieving $520–$720/week (Hornsby Hospital + Hornsby TAFE + Macquarie University proximity) per week.
⏱Our Team
Oliver Alameri
Founder / Director / Builder · MPropDev · PhD Student
Ahmad Alameri
Accounts Manager
Claire Wendell
Project Manager
Estimate Your Build Cost
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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 July 2025
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Costs, approval pathway and fixed-price contract detail for every other build type we deliver in Mount Colah 2079. Hornsby Shire Council regulations and local controls are covered on each page.