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 160 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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Enquiries from contact forms may be shared with partner providers, and we may earn a referral fee from those referrals. Our rankings and scores reflect only our published methodology 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(284) 91
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HomeLux Renovations
5.0(50) 87
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NORMU
5.0(69) 85
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Addstyle Master Builders
4.7(61) 85
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Independent Building Advice
4.8(24) 79
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