Nahuel Acosta Martinez
Perth, WA
“This is a great construction company, and I trust them completely. Tom is always communicative and professional, and his experience really shows in the quality of his work. Highly recommended.”
Google Review
Granny Flats
Granny Flats in Perth, Built for Family or Rental Income
Whether it's for ageing parents, adult kids, or extra rental income, we design and build ancillary dwellings across Perth's western suburbs with transparent, disclosed pricing from concept through to handover.
Licensed WA Builder (BC105853)
Permits and approvals handled for you
Based in Subiaco
Free Granny flat Calculator
Granny flat Cost Calculator Perth
Get an instant indicative estimate for your project. Cost of works and our disclosed management fee are shown separately, consistent with your formal quote. All prices include GST.
Estimating new builds only. Need a different project type? Try the full calculator.
1
Choose Project Type
2
Project Size
40
m²3
Finish Level
4
Optional Add-ons
Your Estimate
🏡Granny flat
Estimated Cost of Works
$78,200
$1,955 per m²
Materials, labour and subcontractors only — our management fee is shown separately below.
Low
$61,200
High
$102,000
Management fee (18.5%, locked & disclosed)$11,322 – $18,870
Estimated total project cost$72,522 – $120,870
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Estimates are indicative only. Cost of works excludes our locked, disclosed 18.5% management fee, shown separately above. Final pricing requires a formal site-specific quote from our team.
Overview
A Second Dwelling, Done Properly
A granny flat is one of the most efficient ways to add liveable space or rental income to a property without a subdivision — it sits on the same title as your existing home, which generally means a simpler and faster approval process than a full block split.
WA's April 2024 R-Codes update removed the minimum lot size requirement and, for most compliant designs under 70m², removed the need for full planning approval altogether — a building permit is usually enough. We track exactly which approval pathway applies to your block so you're not paying for a process you don't need.
As your licensed builder we manage the design, whichever approvals apply, and the construction, with every cost disclosed against a single, locked management fee — the same standard we apply to every project, regardless of size.
What's typically included
Design within your block's R-Code limits (no minimum lot size since April 2024)
Whichever approval pathway applies — building permit only, or full planning approval
Separate metering, plumbing and electrical
Full kitchen and bathroom fitout
Guidance on rental rules, including STRA registration if you're planning Airbnb-style stays
Full BCA-compliant construction, fully insured
Google Reviews
Real feedback from Regional Construct clients
5.0 stars across 19 Google reviews. Rotating through real client feedback below — see the full set on Google.
Read All Google ReviewsWhy We're Different
Why We Build This Way
Built to Finish What We Start
Our management fee is locked and disclosed before work starts, so we're financially committed to your build the same way on day one as on day one hundred — steady quality and pace, first brick to handover.
Full Cost Transparency
You see the real cost of your build and exactly what our fee covers, every time.
Fair, Disclosed Variations
Scope changes are billed at the real invoiced cost with the same disclosed fee added — what you see is what you pay, every time.
Flexibility
Change finishes or scope mid-build and your fee structure stays exactly the same.
FAQ
Common Questions
Granny flats we build typically land between $160,000 and $250,000+ depending on size and finish level. Our genuine entry point is a 40m² build at our budget per-m² rate, which runs from $72,000 cost of works — though most clients choose a larger or higher-finish build in the $160,000+ range. As a rough per-square-metre guide, budget roughly $1,800–$3,000/m² depending on finish — so a 60m² ancillary dwelling commonly runs from $160,000 upward including a separate meter and landscaping. Use the estimator below for an indicative figure based on your own size and finish, or get a free, site-specific quote.
Since WA's April 2024 update to the Residential Design Codes, most compliant granny flats under 70m² no longer need full planning approval in residential zones — a building permit is usually enough, which speeds up the process significantly. Whether your project qualifies depends on your specific block and design, so we confirm the exact pathway during the initial assessment and manage whichever approval is required.
WA removed the minimum lot size requirement for granny flats in April 2024, so nearly any residential block can now qualify, subject to setbacks, site coverage and other R-Code checks specific to your property. The old rule requiring the granny flat to match the main house's colour, roof pitch and materials has also been scrapped, giving you more design freedom than before.
Current WA rules allow you to rent a granny flat to any tenant, not just family — including standard long-term tenancies. If you're planning short-term or Airbnb-style stays, you'll need to register on the WA short-term rental accommodation (STRA) register. We'll walk you through what applies to your plans as part of the initial consultation.
No — a granny flat (ancillary dwelling) sits on the same title as the main house, unlike a subdivision. This generally makes approval faster than a full subdivision, though R-Codes still govern setbacks, size limits and parking.
Ancillary dwellings in WA are capped at 70m² of enclosed habitable floor area under the current R-Codes. Verandahs, patios and carports typically don't count toward that limit, provided they meet your local council's site coverage rules — so there's often more usable outdoor space available than the 70m² figure suggests. We confirm the exact limit for your property during the site assessment.
You see the real, invoiced cost of materials and trades, plus one flat, locked management fee agreed before work starts — the same rate regardless of project size, with no separate margin hidden inside supplier quotes.
Yes — the calculator above is completely free, gives an instant indicative estimate, and doesn't require you to submit any details unless you want a formal, site-specific quote afterward.
It's a genuine indicative range based on real Perth build rates for size and finish level, not a marketing number. Your exact cost depends on your block, chosen finishes and any site-specific factors, which we confirm during a free assessment.
Our Promise
Our 10% Guarantee
Transparent Pricing, Backed By Our Guarantee
If your final cost tracks more than 10% above our upfront estimate, we'll automatically bring in our in-house experts for a free consultation — reviewing where costs are tracking over and identifying options to bring your build back on budget. No extra charge, and we act on it proactively, before you have to ask.
Get Started
Ready to Start Your Granny Flat?
No pressure, no obligation — tell us a bit about your block and what you have in mind, and we'll come back with honest advice on size, approvals and cost.
Financing your project? Ask us about staged payment structures aligned to build milestones — we're happy to talk through options.
Where We Work
Based in Subiaco, working across the western suburbs including Shenton Park, Daglish, Jolimont, Karrakatta, Nedlands, Claremont and the wider Perth metro area.
Read our full guide: Granny flat costs in Perth