Conversion Mortgages > Valuing a barn conversion.
How to value a barn conversion?
Barn conversions involve transforming a non-residential building into a unique home, which means that standard ‘per square metre’ estimates or estate agent comparisons often won’t tell the whole story. Looking for the top line?
Barn conversions are valued similarly to residential homes, based on location, size, and the quality of the finish.
Lenders use your projected end value (GDV) to determine borrowing limits.
Stage valuations during construction guide the release of funds.
A final RICS valuation confirms your home’s completed worth for remortgage or sale.
Understanding barn conversion value
A barn conversion’s value is a balance of:
Starting value: the price or existing worth of the barn before conversion.
Build cost: materials, labour, and professional fees.
End (or “Gross Development”) value: what your finished home will be worth on the open market.
For most self-build or conversion mortgages, the end value is what matters most, as it defines how much you can borrow, the interest rate you’ll pay, and the equity you’ll create once the project is finished.
You will want your end value to exceed your total project cost by a comfortable margin.
How to estimate your barn conversion value
If you’re still planning your project or haven’t purchased a barn yet, it’s important to estimate the potential end value early. We recommend that you:
Research local comparables.
Check recent sales of converted barns or similar rural homes in the area.
Use the Land Registry or portals like Rightmove and Zoopla.
Compare size and setting.
Divide each comparable’s sale price by its internal floor area to get a £/m² rate.
Adjust for features like views, land, or parking.
Apply your rate to your proposed design.
Multiply the £/m² figure by your planned finished floor area.
Refine the specification.
Add 10–15% for high-end finishes, or reduce for basic ones.
Example:
Local conversions sell for around £3,400 per square metre. Your planned 160 m² home might therefore be worth around £545,000 on completion, if finished to a similar standard.
How valuers assess a barn conversion
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Before you build or buy
Valuers will look at:
- The barn’s current market value and land potential.- Existing permissions (Class Q or full planning).
- Your estimated build costs and project plans.
- Comparable completed conversions in the area.
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During construction
With self-build or conversion mortgages, funds are released in stages. Each stage is supported by an updated valuation confirming:
- Progress of works so far.
- Estimated value to date.
- Forecasted final value.
This is one of the most significant advantages of working with a broker like Mayflower, who can coordinate valuations and schedule them in conjunction with your contractor’s schedule.
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After completion
Once your home is complete, a RICS valuer conducts a final assessment. They’ll consider:
- Quality of materials and craftsmanship.
- Adherence to approved plans and building regulations.
- Energy performance (EPC).
- Internal layout and functionality.
- Market demand for similar properties.
The resulting figure from this is your final market value, which is used to refinance your mortgage or calculate your equity.
What does a realistic valuation look like?
Purchase a disused barn for £160,000.
Spend £240,000 on design, materials, and build.
Your total investment = £400,000.
Comparable local homes of similar size and spec sell for around £550,000.
Your final valuation = £550,000.
Meaning you’ve created £150,000 of equity even before considering long-term property appreciation.
What affects a barn conversions value?
Increases Value
Desirable location with good access and views.
High-quality insulation and EPC rating (A or B).
Structural integrity and compliance with Building Regulations.
Modern layouts and natural light.
Retained period features (beams, stonework, vaulted ceilings).
Professional documentation and warranty in place.
Decreases Value
Incomplete works or visible snagging.
Poor access, shared driveways, or right-of-way issues.
Agricultural ties are restricting occupancy.
Lack of certificates or warranties.
Overinvestment, by exceeding the area’s ceiling value.
Maximising long term value.
Once the conversion is complete, value is something you can continue to nurture and grow. Regular maintenance of the roof, stonework, and timber ensures the structure remains in peak condition, reassuring future buyers or valuers of its long-term durability. Investing in sound insulation, renewable energy systems, or smart-home technology can also raise the energy rating and comfort level, both of which are now key valuation drivers.
Keeping a simple ‘property file’ of every improvement, like boiler servicing or any new certificates, will also make future valuations faster and easier. And if you ever decide to extend, adapt, or refinance, these records will serve as proof of ongoing care and compliance.
Why use a barn conversion finance specialist?
At Mayflower, we’ve guided hundreds of clients through barn conversions, self-builds, and major renovations. With over 15 years of specialist experience, we understand what lenders require, the necessary paperwork to prepare, and how to ensure your project remains funded smoothly from the initial survey to final sign-off.
✔ Expert mortgage advice for conversion projects
✔ Access to exclusive lenders who understand non-standard properties.
✔ Quick, confident decisions that keep your build on schedule.
✔ A dedicated adviser supporting you through planning, VAT reclaim, and refinancing.
✔ Access to our Self Build Saver Solution, designed to save you thousands over the life of your project.
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Best Self Build Mortgage Advisory Firm
Design and Build Awards 2025
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Best Specialist Broker
Finalist at the 2025 Mortgage Strategy Awards
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Best Specialist Broker
Finalist at the 2025 Financial Reporter Awards
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NaCSBA Gold member
National Custom & Self Build Association
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NACFB Member
National Association of Commercial Finance Brokers
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AMI Member
Association of Mortgage Intermediaries
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STA
Structural Timber Association Member
Want help understanding the value of your barn conversion?
. Let’s ensure your hard work pays off with a valuation that accurately reflects the true quality of what you’ve built, and a mortgage plan designed to help you move forward.