Realistic London cost ranges for loft conversions, rear and side-return extensions, kitchen extensions and full renovations — by borough and specification level. Every figure is excl. VAT, drawn from dated 2024–2026 published cost guides and the Hampstead Renovations project ledger, with the source shown under each result. It is a planning range, not a quote.
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No black box. Each range states where it comes from and what it excludes.
Loft, extension and kitchen ranges come from published 2024–2026 London cost guides, with the publisher and figure date shown beneath every result.
Flat and house renovation bands draw on the Hampstead Renovations project ledger, cross-checked against published component costs.
Figures are normalised to exclude VAT wherever the source allows. Where a source's VAT treatment is unstated, the band is flagged as indicative market context and never multiplied.
Basement costs swing too widely on waterproofing, access and ground conditions for a headline range to be honest — the calculator routes you to a bespoke assessment instead.
When you are ready, our architects, engineers, surveyors and builders turn your range into a fixed, itemised quotation under one contract.
Tell us about your project and we will respond the same day.
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