barnconversioncost.co.uk

Barn conversion 18-month cashflow

Build-cost bands are the site's own indicative model, inflated to a Q2 2026 footing via the ONS Construction Output Price Index (April 2026). Class Q rules current to the 21 May 2024 GPDO amendment.

A £500,000 barn conversion typically front-loads spend at months 3 (re-roof / shell), 9 (M&E first fix) and 14 (kitchen and final). Retention 5% holds back ~£25,000 to month 18+.

Spend by quarter, £500,000 budget

Months 1-3: pre-constructiondesign, surveys, fees
£35,000
Months 4-6: strip-out & shellre-roof, structural, walls
£120,000
Months 7-9: M&E first fixASHP, drainage, electrics
£110,000
Months 10-12: second fixUFH, plaster, joinery
£95,000
Months 13-15: finishes & kitchenkitchen, bathrooms, decor
£85,000
Months 16-18: snag, completionretention release, landscaping
£30,000
Less VAT431C reclaim (month 19-24)
-£28,000

Retention

Standard JCT and JCT minor-works contracts hold back 5% retention, of which half (2.5%) releases at practical completion and the other half at end of defects (12 months later). Plan cashflow around the late release.

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Reviewed for build by O. Wakefield-Smith, Digital Signet research, Q2 2026. A chartered surveyor (RICS MRICS) sign-off is being procured for the live site. Statutory and tax figures bracket their published ONS, gov.uk or HMRC source on the page where they appear; the £/m² build-cost bands are the site's own indicative model, not a published dataset.