Barn Conversion Costs | Complete Guide 2025

With plenty of popularity amongst homeowners in recent years, barn conversions continue to be one of the most sought-after types of home. One of the most important factors of a barn conversion project is being able to estimate the overall project cost. From initial surveys to interior finishes, understanding the typical costs involved in building a barn conversion can help you budget accordingly.

Brought to you by the experts at BASE architecture, learn everything you need to know about financing a barn conversion in our detailed cost guide.

Explore our architectural services

What’s the average cost of a barn conversion in the UK?

The average cost of a barn conversion in the UK is £275,000. A barn conversion can cost between £100,000 to £500,000, although the costs can increase depending on the factors involved and the project scope. On average, a cost of a barn conversion costs around £1,700/m2, but can be upwards of £2,500/m2 or more, again depending on the project’s scope, size and requirements.

Factors affecting the cost of a barn conversion

Site surveys and planning permission

Before permission for a barn conversion can be granted, the site will need to be assessed, surveyed and feasibility studies will need to be carried out. There will also be additional planning permission fees depending on the scope of your project. You will need to inform your local authority, and also obtain a lawful development certificate. You can find out more about planning permission for barn conversions in our guide, Navigating barn conversions in the UK.

Ecological surveys

Depending on the location of the barn, you will need to carry out appropriate ecological surveys as well as legal surveys. An ecological survey will determine whether or not your barn is located at the same site as a protected species habitat. Species such as dormice, bats, nesting owls and great crested newts are protected under UK law, and the interference or damage to such habitats can lead to a hefty fine and a conviction. Therefore, it’s recommended you hire an ecological surveyor to determine the suitability of your barn and surrounding land for renovation or conversion.

Learn more here

Bear in mind – a lot of protected species surveys can only be undertaken at certain times of year, in line with the species’ nesting habits – delays of up to seven months are possible, so ensure you factor this in as early as possible. Should a species be found, then your project may be delayed in order to determine a mitigation strategy to ensure the build can still go ahead. Preliminary ecological appraisals and the resulting surveys required can cost anything from £350 to over £1000.

The condition of the barn

You may need to restore, remove or renovate parts of the existing building depending on its condition. When you’re budgeting for your barn conversion, consider the following factors:

The structural integrity of the barn (i.e. timber frame repairs, weakened foundations, damaged beams, unlevel flooring)
Building insulation
Underpinning
The condition of the roof and sidings
Plumbing and any reinforcement works
Electric systems
Material damage due to pests/ rot/ wear and tear
Safety hazards and unsafe conditions (mould, asbestos, unstable structures)

Labour and contracting fees

If you’re converting a barn, you’ll need to hire the right tradespeople to ensure the project is legal, safe within your planning permissions. Typically, you’ll work with:

Surveyors
An architect
Safety inspector
Local planning authorities
Builders
Window fitters
Plumbers
Electricians

Our team can help you with tender and contracting negotiations, so you can find suitable, skilled construction contractors in your area.

Building materials

This will likely take up a large amount of your budget, and can incur a heavy cost depending on the size and condition of your barn. Every building material will need to be accounted for – from concrete for underpinning, to timber frames and support beams, to window glazing and brickwork. Don’t forget equipment hire, if you’re taking on some elements of the project yourself. Diggers, skips and machinery will be needed to be transported to site regularly.

Size of the barn

The larger the barn, the higher the final cost of your barn conversion will be. Having a larger barn can be great for project scope and additional space, but the extra square footage will need to be accounted for in the budget. A larger surface area will incur higher utility costs – installing and upgrading the electrics and plumbing will cost more overall as they’ll need to be more extensive.

As is standard practice, it’s advised to share any building plans and architectural designs with your local planning authorities to ensure any structural changes are approved. At BASE, we work with you closely to create measured surveys to assist with the application process.

Structural layout of the barn

Depending on the existing layout of the barn, you may find yourself facing a more complex build than expected. Any existing internal walls, additional levels, and entrance ways will need to be either restored or removed. If your build incorporates structural changes, such as additional rooms, internal walls, staircases, or even a new storey, this will also need to be factored into the final cost estimate. Final touches such as mezzanine balconies, double height windows and skylights or conservation rooflights will also require a fair amount of budget.

Get inspired with our case studies

Interior features

Beyond structural changes, you’ll also need to budget for interior finishes. This includes plastering, painting and decorating. You’ll need to budget for any interior utilities, including fitting the kitchen appliances, bathroom appliances and light fixtures, as well as furniture, storage and soft furnishings.

Access to the barn

Another hidden cost of a barn conversion is the location and access. It’s not uncommon for barns to be situated in remote areas, with tricky access, single track lanes and potentially limited access to the electrical mains or water system. Factor in how vehicles will access the site to make sure there’s a suitable route – it can cause lengthy delays if you block entrances or damage the surrounding land getting access. Ensure you hire suitable machinery that can access the site safely, and don’t forget about HGVs delivering building materials such as concrete, steel frames and glazing panels.

If you’re ready to start your journey, get in touch with the team at BASE. Our experienced, innovative architects will help bring your vision to life, working with you every step of the way.