Demountable hangar: do you need a building permit?

Three criteria decide the permission: height above ground, ground footprint and floor area, and how long the structure stays in place. A useful hangar is rarely 20 m² or less: once it exceeds that, the principle of article R*421-1 applies, under which new buildings require a building permit.

There are two exceptions. The first is the small structure, exempt from formalities or subject to a simple prior declaration depending on its size. The second is the temporary structure, exempt from formalities while it stays in place for a short time. Both are governed by precise thresholds, set out below.

That a hangar can be taken down, bolted together or placed on pads rather than foundations does not change its status. What the authorities look at is what is installed, its size and how long it stays. A demountable hangar kept for ten years is a building like any other.

The practical consequence: do not count on a structure being reversible to avoid an application. The thresholds of article R*421-2 (exemption), article R*421-9 (prior declaration) and article R*421-1 (permit) decide, and the local urban plan (PLU) of the commune says whether the site can be used for it at all.

Outside protected areas, a structure is exempt from all planning formalities if it is no more than 12 m high and its ground footprint and floor area are each no more than 5 m². That is a shed, not a hangar.

Above 5 m² and up to 20 m² of both footprint and floor area, with a height of 12 m or less, a prior declaration is enough. As soon as either area exceeds 20 m², a building permit is required. The rules of the PLU (zone, setbacks, external appearance) apply in every case, including when no formality is required.

In protected areas, a prior declaration is required up to 20 m² (the 5 m² exemption does not apply there), and a building permit above that. The town hall can tell you whether your land lies within such a perimeter (surroundings of a listed monument, remarkable heritage site, listed site).

Article R*421-5 of the Code de l'urbanisme exempts from all formalities structures that stay in place for only a very short time. The base rule is three months or less. A longer period is allowed for certain uses, for example a structure tied to a cultural, commercial, tourist or sporting event, for the duration of the event and within a limit of one year.

In that case the builder must restore the site to its original condition at the end of the planned period. If the hangar ends up staying longer, the exemption falls away. A structure planned for three months that stays for a full season is therefore outside the framework.

In protected areas these periods are shortened: fifteen days instead of three months for the base rule, and three months instead of one year for the longest period, under article R*421-7. Check this before promising a client or a worksite a date of availability.

The commune's PLU divides its territory into zones, and each zone sets what can be built there. Even where no formality is required, a hangar must comply with the rules of its zone: a site can be refused or restricted even though the area is under the thresholds.

The surroundings of listed monuments, remarkable heritage sites and listed sites add a further check: a prior declaration from 5 m² and longer processing times (see the table). If your land is affected, build those weeks into your schedule.

A rigid demountable hangar, with walls and a heavy frame, is thought of as a small building. A storage tent or fabric large-span structure is designed to be installed and removed, and suits a need of a few weeks or months better. LocationTente offers these fabric structures on its storage tent and large-span pages.

The fire safety regulations distinguish “marquees, tents and structures” (CTS articles): they cover establishments designed to be enclosed in whole or in part, itinerant and covered with a flexible fabric, from 50 people admitted. Between 20 and 49 people, only article CTS 37 applies. These rules concern admitting the public and do not replace planning permission.

If the public enters the hangar (sales, reception, trade show), fire safety adds to planning and the safety commission and the mayor decide. Storage with no public falls outside that question, but remains subject to planning rules.

The file is lodged at the town hall: a prior declaration or a building permit application, depending on the area. The processing clock runs from the filing of a complete file: one month for a prior declaration, three months for a building permit outside protected areas. If the file is incomplete, the town hall has one month to ask for the missing documents, and you then have three months to supply them.

Then allow for ordering, manufacturing and assembling the hangar: a realistic schedule starts from the date of the decision, not the filing. If the project is tied to an event or a worksite with a fixed date, the temporary structure is often the only option compatible with the deadline.

This list avoids the two most common mistakes: ordering before knowing whether the site is allowed, and underestimating how long the structure will really be used.