Every barn conversion quote starts with the same honest answer: it depends on the barn. But that is not much use when you are trying to work out whether a project stacks up before you commit. Here are the real ranges we see on brick and pantile barns around Peterborough and the surrounding Fens, and the things that quietly move the number.
For a straightforward conversion of a sound agricultural building into a finished home, budget £1,500 to £2,500 per square metre of internal floor area. A modest specification with a simple layout sits at the lower end. Bespoke joinery, large structural glazing, natural stone and a complex roof push you to £2,500 to £3,500 per m² or beyond.
So a 180 m² barn, which is a common size once you work within Class Q's 150 m² per dwelling cap or apply for full planning, typically lands between £270,000 and £450,000 for the building work alone. That excludes the purchase of the barn, VAT where it applies, and professional fees.
The single biggest variable is the starting condition. A dry, level, structurally sound building with an intact roof can come in near the bottom of the range. A leaning gable, rotten wall plates and a failed roof can add £40,000 before you have laid a single floor.
It helps to see the spend split out, because homeowners are often surprised by how much disappears before anything looks like a house. Indicative figures for a mid sized conversion:
Much of the land around Peterborough, Whittlesey and the Fen villages sits on soft ground with a high water table. Ground conditions frequently mean piled or reinforced foundations rather than a simple slab, and that can add £10,000 to £30,000. If the site falls within Flood Zone 2 or 3 near the Nene or the Great Ouse, expect a flood risk assessment and possibly raised floor levels.
Many barns here are off the mains gas network, so heating means a heat pump or LPG, and that in turn raises the insulation standard you need to hit for the system to work sensibly. Electricity supply is another one to check early: bringing a new three phase or upgraded supply across a field can run to £5,000 or well beyond.
Ecology is not optional. Bat and barn owl surveys are routinely required with a planning or prior approval application, and the initial survey costs £500 to £1,500. If bats are present, mitigation such as a dedicated roost adds cost and can restrict roof works to certain months of the year, which affects your programme as much as your budget.
This is where people find real savings. Converting a non-residential building into a dwelling usually qualifies for the reduced 5% VAT rate on labour and on materials supplied by the contractor, rather than the standard 20%. On a £350,000 project that difference is worth over £50,000, so it is worth confirming eligibility with your accountant or HMRC before work starts.
On top of the build, allow 10% to 15% for professional fees covering the architect or designer, structural engineer, ecologist and building control. Planning or prior approval application fees are a few hundred pounds, and a measured and structural survey is typically £800 to £2,000.
Then set aside a contingency of 10% to 20%. On new build we would say 10%. On barns, where you genuinely cannot see what is behind the render or under the floor until you open it up, 15% to 20% is the sensible number.
Get a structural engineer to inspect the barn before you exchange contracts, not after. That one report tells you more about your final cost than any square metre rate.
Fix the specification before work begins. Changing a kitchen layout on paper is free; changing it once first fix electrics are in costs hundreds. And be wary of a headline price that seems far below the others: it usually means the structural repairs, drainage or utility connections have been left out and will arrive later as variations.
Usually not. New build often works out at £1,800 to £2,400 per m² with fewer unknowns, whereas a barn carries the extra cost of stabilising and repairing an existing structure. People choose barns for the character, volume and setting rather than to save money.
Class Q permitted development can allow an agricultural building to become a dwelling without full planning permission, subject to prior approval and limits on size and structural work. It does not apply to listed buildings, and many barns in conservation areas or with significant structural need require a full planning application instead.
Allow six to nine months on site for a typical single dwelling conversion, plus three to six months beforehand for surveys, design and the planning or prior approval decision. Bat mitigation, listed building consent or awkward ground conditions can extend that noticeably.
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