French barn conversions: Paperwork comes first

Make sure that the work is covered by a permis de construire or a déclaration préable de travaux, and that the administrative use of the barn has been changed to habitable status

3 September 2019
By Brian McCulloch

Barn conversions have resulted in beautiful homes being created in buildings designed and built for a very different purpose.

Before starting the physical work, though, some paperwork is almost certainly required.

You have to make sure that the work is covered by a permis de construire or a déclaration préable de travaux, and that the administrative use of the barn has been changed to habitable status.

French administrative and tax codes usually apply one of nine different uses to buildings, with the uses being divided into habitable and non-habitable ones.

Most barns were for agricultural use, one of the non-habitable categories, and changing the coding of the building to habitable use is a key step towards getting the correct legal status for a barn conversion.

It involves filling out a form obtained from the local mairie or downloaded online.

Change of use such as this is not usually a problem but it is important to check that the change has been approved, or a pérmis de construire might be ruled invalid at a later stage.

The tax part of the change can be expensive, as agricultural buildings are not taxed, while habitable ones are. A small farmhouse with a barn attached often doubles or triples its habitable surface when the barn is declared habitable – and local taxes are still largely based on the habitable size of the property.

Administrative change of use applies whether the barn is attached to a house, is on its own but has neighbouring properties, or if it is isolated.

Problems getting the administrative change of use are rare but can happen.

Isolated barns are most likely to be affected, especially if the commune has a restrictive plan local d’urbanisme (PLU), or a plan d’occupation des sols, which the PLU replaced.

These plans can sometimes impose blanket bans on changes of use, even where there are solidly constructed barns that are ideal for conversion.

They can be changed by the local council, with amendments then having to be approved by the prefect, which takes time and involves getting the local council on your side.

This is often easier than you think, as rural communes are usually keen to have more people move in.

Where the barn is close to other homes, problems are less likely but can take the form of an arrêté municipal from the council, blocking the change for some reason, such as difficulty of access.

Usually, where the barn is attached to a house, getting an administrative change of use is no problem.

For a permis de construire, the same regulations apply for a barn as for a house.

If, in the case of a barn attached to an existing house, the new surface created by, for example, converting cow byres into an additional bedroom is under 40m², the formalities can be completed by making a déclaration préable de travaux from the mairie, as long as the commune has a PLU.

For projects of more than 40m², a full permis de construire is required. This 40m² rule replaced a previous 20m² rule to make it easier to expand existing houses.
If the commune does not have a PLU, the old 20m² rule still applies, meaning a déclaration is sufficient.

Usually there is no problem with the mairie unless it is judged that the barn to be converted is too far from electricity and water sources.

Some communes are open to projects involving autonomous supplies.

If the commune has a collective sewerage system, being too far away to be able to join it is not necessarily a reason for refusal, as long as you can install a septic tank or other approved sewage treatment system.

This will have to meet standards and inspections by water treatment experts, usually attached to the canton or communauté de communes.

Builders must be aware that any materials used have to meet thermal regulations introduced in 2012, known as RT2012.

Broadly, these state that replacement fixtures, such as windows, cannot degrade the thermal performance of the building, while new fixtures have to meet thermal standards, effectively meaning double glazing and insulation is now required.

Using an architect’s drawings is compulsory if the interior surface of the converted barn is more than 150m². 

This rule includes any mezzanine floors, and effectively means most barn conversions fall under the rule.

If you have a house with a barn attached, the 150m² will be measured by adding the surface of the existing house and the barn.

The same form is used for a permis de construire for a barn conversion as for building a house.

They often take a bit longer to process, though, so if you get a letter saying the regulatory timeframe will be extended, do not panic.

It is just that the urban planners take longer for projects which are outside the usual standardised plans they see, but outright refusals are rare.

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