What is a barn conversion?

A barn conversion turns an agricultural or rural building into a home while keeping its character: the brick or stone walls, roof timbers and large openings. It involves structural repair, insulation, new services and often a new floor slab.
How much does a barn conversion cost in Tonbridge?
In Tonbridge, a barn conversion typically costs £2,000–£3,350 per m² of floor area, including VAT at usually 5% (reduced rate for creating a new dwelling). For a typical 150 m² project that is roughly £300,000–£502,500. We start from a UK-wide guide and adjust it for the South East, where labour and materials are typically about 12% above average. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| Smaller project (105 m²) | £210,000–£352,000 |
| Typical project (150 m²) | £300,000–£502,500 |
| Larger project (210 m²) | £420,000–£703,500 |
| Rate per m² | £2,000–£3,350 |
The biggest cost drivers are:
- Glazing and finishes
- Condition of the existing structure
- Planning conditions and ecology
- Services and drainage
Your exact price depends on the survey and drawings. The guide price tool gives a quick range in the meantime.
Do you need planning permission for a barn conversion in Tonbridge?
The approval route for Tonbridge is set by planning law in England. In England converting an agricultural building into a home needs either full planning permission or prior approval under Class Q of the permitted development rules, which limits floor space and the number of homes. Listed barns also need listed building consent.
Building regulations approval comes from the council’s building control service or a registered building control approver. The work is inspected at key stages, such as foundations, drainage and insulation, and a completion certificate is issued at the end.
We check this for your address before design work starts, so there are no surprises later.
What we handle
Handled as part of most barn conversions:
- New roof covering where needed
- Insulation that respects the existing fabric
- Planning or prior approval application
- Ecology and bat survey coordination
- Structural survey and feasibility
- Building control completion
How long does it take?
Expect 6 to 12 months on site depending on condition. Before that, surveys, drawings and approvals usually take 4 to 9 months, longer if the council asks for changes.
Building in Tonbridge
Commuter towns across the South East have many 1930s and post-war semis that suit rear extensions and hip-to-gable loft conversions.
Projects in Tonbridge (TN9) are surveyed in person before we quote, so the price reflects your actual property.
How it works
- 01
Free visit
We look at the property, talk through what you want and measure up. There is no charge and no obligation.
- 02
Design and fixed quote
Drawings, structural calculations and an itemised, fixed price for the agreed specification.
- 03
Permissions sorted
Applications, building control and neighbour arrangements, all before the start date.
- 04
Build and handover
Work follows the agreed programme, with inspections along the way and a completion certificate at the end.
Questions about barn conversions in Tonbridge
Do I need planning permission for a barn conversion?
Yes. A barn conversion needs planning permission or, in England only, prior approval under the agricultural permitted development rules where the building qualifies. Listed barns also need listed building consent.
Can I get a mortgage for a barn conversion?
Specialist self-build and conversion mortgages release money in stages. We can provide the staged costings lenders ask for.
How much does a barn conversion cost in Tonbridge?
In Tonbridge, a barn conversion typically costs £2,000–£3,350 per m² of floor area, including VAT at usually 5% (reduced rate for creating a new dwelling). A typical 150 m² project comes to roughly £300,000–£502,500. Your fixed price depends on the survey and drawings.
How long does a barn conversion take in Tonbridge?
Typically 6 to 12 months on site depending on condition. Design and approvals beforehand usually take 4 to 9 months.
Is VAT reduced on a barn conversion?
Usually yes. Converting a non-residential building into a dwelling normally qualifies for the reduced 5% VAT rate on building work. Our guide prices assume this rate.
