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19 January 2021

Extension costs

Ever wondered how much an extension costs? We've got the latest figures from RICS to help make it that little bit clearer
Extension plans_jul19 483003
RC
Rachel Christie
In this article

There's no doubt that extensions cost a lot of money, but a lot of the time they're well worth the investment. It's always a sensible idea to get two or three quotes before you commit, but here's a general idea of costs to get you started.

If you're a Which? member, you can log in now to unlock RICS pricing data for various sizes of extensions.

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Total project costs of house extensions

House extensions size and costs Floor size (metres) Flat roof Pitched roof
Single storey with one window 3x3
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  3x5
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  4x4
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  4x6
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Double storey with two windows 3x3
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  3x5
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  4x4
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  4x6
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Extension planning

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