Home Extension Builder St Marys — Approved in 60 Days
St Marys 2760 extensions with tight approval timelines. CDC where eligible (~15 days), DA via Penrith City Council in 40–60 days. Construction 12–24 weeks depending on scope.
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MBA NSW0476 300 300Quick Answer
A home extension in St Marys costs $150,000–$600,000+. Rear extension from $150K, second-storey addition from $300K. Buildana manages design, Penrith City Council approvals, and construction under one fixed-price contract.
St Marys Home Extensions — Fixed Price
A home extension in St Marys reads the block against the corridor — the R4 pockets near the future Metro station carry value the wing is checked against, while the 1950s-1980s homes beyond extend on the value read.
The fibro gets the licensed strip-out first, the older framing gets checked, and the junctions are engineered.
At the $850K to $1.3M entry, the wing on the settled streets keeps the money in the building.
We build these fixed-price, licence HBL 487805C. Get our extension scope, with the zoning checked, before you commit.
Buildana manages the complete home extension process in St Marys — 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 St Marys from $150K
- Penrith City Council DA and CDC approvals managed
- Ground floor, rear and second-storey additions
- M — structural engineering included
- 1950s–1980s + 2010s+ R4 apartments-era homes assessed for extension suitability
- Connect new to existing — clean, matched finish
- 6-year structural warranty
- Free design consultation — near St Marys station
Reviewed by Oliver Alameri
Licensed Builder (NSW 487805C) · Master of Property Development · PhD Student · Building across Western Sydney since 2010
The Metro reprices the core
St Marys' future Metro station is repricing the blocks around it — some carry R4 value worth more than any wing, so I check the position before design money moves.
The settled streets beyond extend on the standard value logic.
Older stock handled
The 1950s-1980s framing is checked before it borders new structure, and fibro gets the licensed strip-out first.
Both sit in the quote from the outset, not billed as the cladding comes off.
Home extension builder in St Marys — key facts
- Suburb
- St Marys, NSW 2760
- Council / LGA
- Penrith City Council (City of Penrith)
- Primary zoning
- R2
- Typical lot size
- 450–750m² typical (Cranebrook/Werrington/Cambridge Park/Kingswood/St Marys); 250–450m² master-planned (Jordan Springs/Caddens/Glenmore Park new release)
- Soil class
- M
- Median house price
- $850K–$1.3M typical; $1.0M–$1.6M Glenmore Park/Jordan Springs premium master-planned; $1.6M–$3.0M+ Mulgoa/Wallacia/Castlereagh acreage
- Home era
- 1950s–1980s + 2010s+ R4 apartments
- 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 |
|---|---|
| Simple rear extension (single wall removal, no roof change) | $90,000 – $200,000 |
| Moderate extension (multiple openings, roof extended) | $200,000 – $380,000 |
| Complex extension (structural steel portals, re-roofing) | $380,000 – $600,000 |
| Second-storey tie-in (existing house re-engineered) | $350,000 – $650,000 |
Prices are indicative for Western Sydney (2025). Actual costs depend on site, specifications, and approvals.
How It Works
From First Call to Final Key
The first job on an extension is finding out what you're extending onto. St Marys homes from the 1950s–1980s + 2010s+ R4 apartments were built to different standards — we open walls, check footings, verify load paths. The existing house has to carry the new work.
⏱Design follows the existing roof. A bad extension looks like a bolt-on; a good one reads as original. Matched brickwork or contrasting render (whichever the architecture calls for), tied-in roofline, continuous flooring where it should be continuous.
⏱Construction happens while you live in the house. That means weatherproofing every night, staging the works so kitchens and bathrooms don't disappear on the same week, and keeping the site clean of debris that doesn't belong in a family home.
⏱Finish is seamless. Paint match, floor match, roofline match, brick match where possible. The only way to tell the extension is new is the date on the plans.
⏱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
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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
Extend Your Home in St Marys
Free design consultation for St Marys 2760. We'll assess your home, design the extension, and provide a fixed-price quote.
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Other Buildana services in St Marys
Costs, approval pathway and fixed-price contract detail for every other build type we deliver in St Marys 2760. Penrith City Council regulations and local controls are covered on each page.