Granny flat or extension cost estimator

Work out an approximate cost for adding a granny flat or home extension in Perth based on size and project type.

Estimated project cost

A$ 143,000 - 190,000

The range accounts for site conditions, council requirements and finish level.

Local price context: based on 171 price points from reviews and provider websites across this directory. Recorded prices span jobs of very different sizes, so compare quotes for your exact project.

This is a rough estimate only; a builder needs to assess your site and plans to give an accurate quote.

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Your calculator details and the estimate go with your enquiry so builders can quote your actual project. Just add your area, timeline, and contact details.

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You agree that when you send this enquiry we share it with providers relevant to your request.

When you submit an enquiry through our forms, we may share it with partner providers who can do the work, and we may earn a referral fee from those introductions. Our rankings and scores are based only on our published scoring method and are never influenced by referral fees.

Get quotes from top-rated home builders

Ranked by our published rubric from recent Google reviews, weighted by relevance to this service (the same order as the category page).

Home Venting Solutions - Rangehood and Venting Specialists
4.9(285) 91
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HomeLux Renovations
5.0(50) 87
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NORMU
5.0(70) 85
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Addstyle Master Builders
4.7(61) 85
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Kev Renovations – Luxury Home Extensions & Bathrooms, WA
5.0(20) 71
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