November 10, 2024

Barn conversions are rising in popularity in the UK, driven by the favourable planning rules and a growing demand for sustainable, character-rich properties for both the residential and holiday rental markets. But how much does it cost to convert a barn? And what is the cost per square metre?

In this article, we cover the costs of barn conversions for a single-storey and a double-storey conversion. We also bring you up to speed on UK planning rules and the differences between classifications of barn conversions in the UK.

Start your free trial with BuildPartner today to get the most accurate estimate of converting a barn based on your own dimensions and specifications.

Barn Conversion Cost Considerations

The costs in this guide assume that the barn conversions do not require new roofs or walls.

Since barn conversions vary in size and there is very limited data on the average size, we based our calculations on a ballpark figure of 80m2 of floor space per storey (160m2 for a double-storey conversion).

• The double-storey barn conversion comprises four bedrooms, one en-suite, a bathroom, a WC, a kitchen, a living room, and a cloakroom.
• The single-storey barn conversion comprises three bedrooms, a bathroom, a WC, a kitchen, and a living room.

We also provide a breakdown per square metre so you can work out the costs for your project – if you happen to know the dimensions.

In the cost breakdown provided later, you’ll notice a disproportionate amount of the cost is attributed to foundations and substructure. The main reason for this is that most barns have shallow foundations, which are unsuitable for modern residential standards. 

Therefore, underpinning – the technique that stabilises existing foundations – accounts for a significant part of the cost. 

Build Specifications and Supplier Benchmarks 

In terms of build specification, our BuildPartner pricing tool gives you three options (which can be revised by item at a later point):

 

• Basic spec is a basic finish; e.g. Leyland, Everest, Wickes.
• Standard spec is a standard finish; e.g. Dulux, Hamilton, Slim Line.
• Premium spec is a high-spec finish; e.g. Farrow & Ball, Fine Line, Siemens.

 

For this particular cost breakdown, we have selected standard spec. In addition, for each specification, we’ve provided a range of prices to reflect the varying types of contractors:

• Low benchmark – smaller companies are generally lower cost but less specialised and with low project management function; good for low/mid-spec projects and tight budgets.

• Mid benchmark – medium-sized companies offer a balanced mix of cost-effectiveness and specialisation; good for mid-range projects for effective execution within moderate budgets.

• High benchmark – larger companies generally have a higher cost base but can handle a wide variety of specialist tasks; good for mid/high-spec projects and project management.

 

Cost Of Building A Single-Storey Barn Conversion

Here’s a table showing the average building costs of converting a single-storey barn for a standard-spec project in the UK:

Single-Storey Barn Conversion	Total Average Build Cost			Average Cost Per Sq Metre
	Low Benchmark	Mid Benchmark	High Benchmark	Low Benchmark	Mid Benchmark	High Benchmark
East Anglia	£197,570	£215,531	£233,492	£2,470	£2,694	£2,919
London	£222,543	£249,590	£276,462	£2,782	£3,120	£3,456
Midlands	£193,633	£211,236	£228,839	£2,420	£2,640	£2,860
North England	£191,524	£209,931	£227,425	£2,394	£2,624	£2,843
Northern Ireland	£188,858	£202,767	£219,665	£2,323	£2,535	£2,746
Scotland	£191,845	£209,285	£226,726	£2,398	£2,616	£2,834
South East	£204,985	£229,210	£254,306	£2,785	£3,114	£3,418
South West	£195,676	£220,919	£242,473	£2,470	£2,761	£3,031
Wales	£193,781	£216,683	£232,060	£2,422	£2,709	£2,901
Average	£197,824	£218,350	£237,939	£2,496	£2,757	£3,001

 

All costs exclude VAT.

 

Here’s what the data shows for the cost of converting a single-storey barn to a standard spec:

 

• The minimum cost is £188,858, and the maximum cost is £276,462.
• The total average cost is £218,038, or £2,751 per square metre.

 

Barn Conversion Cost Breakdown By Project Stage – London

Here are the associated costs for the different stages of a barn conversion for a standard-spec project – when using a mid-benchmark contractor in London:

 

Total	£249,590	100%
Foundations and substructure	£74,492	29.8%
Preliminaries	£21,907	8.8%
External windows and doors	£15,658	6.3%
Units, worktops and kitchen appliances	£13,721	5.5%
External wall structure and lining	£13,199	5.3%
Floor preparation and finishes	£11,942	4.8%
Decoration	£10,739	4.3%
Heating and cooling	£10,617	4.3%
Demolitions	£9,779	3.9%
Steel and structural supports	£9,577	3.8%
Floor structure and lining	£9,546	3.8%
Wired appliances	£8,336	3.3%
Wall preparation and finishes	£7,888	3.2%
Ceiling structure and lining	£7,851	3.1%
Drainage and pipework	£7,120	2.9%
Plumbed appliances	£5,250	2.1%
Internal wall structure and lining	£4,328	1.7%
Internal doors and frames	£3,469	1.4%
Wiring and fuseboards	£1,767	0.7%
Ceiling preparation and finishes	£1,553	0.6%
Fixtures and fittings	£850	0.3%

Cost Of Building A Double-Storey Barn Conversion

Here’s a table showing the average building costs of converting a double-storey barn for a standard-spec project in the UK:

 

Double-Storey Barn Conversion	Total Average Build Cost			Average Cost Per Sq Metre
	Low Benchmark	Mid Benchmark	High Benchmark	Low Benchmark	Mid Benchmark	High Benchmark
East Anglia	£262,110	£285,938	£309,766	£1,638	£1,787	£1,936
London	£298,323	£334,438	£370,785	£1,865	£2,090	£2,317
Midlands	£256,607	£279,935	£303,263	£1,604	£1,750	£1,895
North England	£253,972	£278,056	£301,227	£1,587	£1,738	£1,883
Northern Ireland	£249,811	£267,930	£290,258	£1,535	£1,675	£1,814
Scotland	£254,019	£277,112	£300,205	£1,588	£1,732	£1,876
South East	£274,702	£307,166	£337,134	£1,866	£2,087	£2,290
South West	£259,449	£293,086	£321,680	£1,638	£1,832	£2,011
Wales	£256,788	£287,135	£307,782	£1,605	£1,795	£1,924
Average	£262,864	£290,089	£315,789	£1,658	£1,832	£1,994

 

All costs exclude VAT.

 

Here’s what the data shows for the cost of converting a double-storey barn to a standard spec:

 

• The minimum cost is £249,811, and the maximum cost is £370,785.
• The total average cost is £289,581, or £1,828 per square metre.

 

Barn Conversion Cost Breakdown By Project Stage – London

Here’s an example of the associated costs for the different stages of a conversion for a standard-spec project – when using a mid-benchmark contractor in London:

 

Total	£334,438	100%
Foundations and substructure	£74,492	22.3%
External wall structure and lining	£26,397	7.9%
Preliminaries	£23,963	7.2%
Floor preparation and finishes	£21,219	6.3%
External windows and doors	£20,677	6.2%
Floor structure and lining	£19,021	5.7%
Decoration	£17,434	5.2%
Units, worktops and kitchen appliances	£16,240	4.9%
Demolitions	£16,115	4.8%
Ceiling structure and lining	£13,675	4.1%
Heating and cooling	£13,657	4.1%
Wall preparation and finishes	£12,399	3.7%
Wired appliances	£11,152	3.3%
Steel and structural supports	£10,068	3.0%
Internal wall structure and lining	£8,657	2.6%
Drainage and pipework	£8,527	2.5%
Plumbed appliances	£7,992	2.4%
Internal doors and frames	£4,966	1.5%
Ceiling preparation and finishes	£3,088	0.9%
Wiring and fuseboards	£1,767	0.5%
Joinery	£1,624	0.5%
Fixtures and fittings	£1,308	0.4%

 

Do I need planning permission to convert a barn?

In most cases, you don’t need to submit a full planning application to convert a barn, but it’s a good idea to obtain something called a lawful development certificate.

Despite the name, it’s actually not a legal requirement, but it does protect you in the event of planning policies change. Without one, if your conversion is later deemed to be unlawful, this could result in fines or, worse, the demolition of your project.

To get started, you need to submit your designs by giving “prior notification” to your local authority. They’ll review your designs to ensure you’re within your permitted development rights and a host of other factors such as transport, noise, and flood risk.

It can take anywhere between two to three months to gain approval.

If you plan on extending your barn, however, you will need to apply for planning permission.

Barn Conversion Classifications – UK

In the UK, barn conversions have three main classifications (Q, R, and S). Here’s what each covers:

Class Q – Agricultural to Residential

Class Q allows the conversion of agricultural buildings, such as barns, into residential homes without full planning permission. 

To meet the criteria for Class Q, the barn must:

• Have been used solely for agricultural purposes before 20 March 2013.
• Be no greater than 1,000m2 of floor space.

If a barn conversion falls under Class Q, up to ten separate dwellings (previously five) can be created, providing that the maximum size of a dwelling is no greater than 150 square metres. In addition, structural alterations must not extend beyond the original footprint of the building.

Class R and Class S – Agricultural to Flexible Commercial Use

Class R permits the change of use from agricultural buildings to a range of commercial uses, such as retail, offices, restaurants, hotels, or leisure facilities.

Class S allows the conversion of agricultural buildings into state-funded schools or registered nurseries (education facilities).

To meet the criteria for Class R and S, the barn must:

• Have been used solely for agricultural purposes before 3 July 2012.
• Be no greater than 1,000m2 of floor space.

Also, the location must not be within protected areas, such as national parks or areas of outstanding natural beauty (AONB).

Proposed Legislation Changes

The previous Conservative government proposed plans to relax rules on barn conversions in national parks and AONBs. These were widely condemned by several key figures, including Kevin Bishop, the CEO of Dartmoor National Park Authority, who said:

“The ability to convert any agricultural barn to an open market house would cause untold damage to our landscapes and do nothing to support the provision of affordable housing.”

The new Labour government has yet to comment on these plans.

Average Cost To Convert A Barn In The UK

So, how much does a barn conversion cost in the UK? Based on the two types covered in this article, you can expect that converting a barn to cost on average (when using a mid-benchmark contractor):

• Single-storey barn – £218,038, or £2,751 per sq metre.
• Double-storey barn – £289,581, or £1,828 per sq metre. 

Depending on the specifications, the cost of the work for a barn conversion would range between £188,858 and £370,785. 

Please remember that these costs do not include VAT, and there may be other additional costs, such as obtaining planning permission, conducting structural surveys, making unexpected repairs, and completing custom finishes.

Start your free trial with BuildPartner today to get the most accurate estimate of converting a barn based on your own dimensions and specifications.