House extension: what permissions?

The house extension

saves valuable m2.

An additional floor for your parental suite, a new office conducive to teleworking or a bright veranda as a living room allow you to enlarge your accommodation.

What is a house extension?

In terms of town planning, a house extension is an

of the surface of the latter.

The extension has the following features:

• It must enlarge the initial dwelling, not create it

• It must have a lower surface than the initial housing

• It must be attached to the initial accommodation

• It can be horizontal or vertical

• It can be created by elevation, excavation or enlargement

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The house extension can pursue several objectives, in particular, to create:

• an additional bedroom

• veranda

• a parental suite

• a desk

• a floor

• a dining room

Before embarking on the work, planning permission can be issued to you to carry it out legally.

What planning permissions are required for a house extension?

The main planning permissions required for house extensions are the prior declaration of work and the building permit.

They depend on the surface created.

Read alsoBuilding permit: formalities and procedures

Check the PLU before any house extension project

The Local Urbanism Plan (PLU), which replaced the Land Use Plan (POS), is a veritable mine of information for you.

It allows you to find out what is or is not authorized to be done in terms of town planning in your municipality or in your community of municipalities.

In particular, it can specify information specific to house extensions.

For instance :

• a maximum height for an elevation

• maximum footprint

• a particular color for the shutters of an additional bedroom

• a material to use

The objective of the PLU is to aim for architectural harmony throughout the city.

But even more, to enforce environmental, thermal or acoustic standards.

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The PLU can be consulted at your town hall.

Some municipalities also make it available to users on their website.

Find out before you start your extension work.

House extension and prior declaration

When they are not subject to a building permit, the law requires

.

Concretely, must be preceded by a prior declaration, house extension work located:

• In the urban area of ​​a municipality with a Local Urbanism Plan (PLU) or a Land Use Plan (POS): for

  extensions up to 40 m²

  , if the

  total surface area envisaged is less than 150 m2

  .

• In other areas of a municipality with a PLU or a POS: for

  extensions up to 20 m²

  .

• If the municipality has no PLU or POS: for

  extensions up to 20 m2

  .

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House extension and building permit

The building permit is mandatory for all the following house extension projects:

• In the urban area of ​​a municipality with a PLU or a POS: for

  house extensions of more than 40 m2

  .

  But also those of

  more than 20 m2, if the total surface is more than 150 m2

  .

• In other areas with a PLU or a POS: for

  house extensions of more than 20 m2

  .

• If the municipality has no PLU or POS: for

  house extensions of more than 20 m2

  .

Good to know

Prior declaration and building permit are deposited at the town hall.

Are there planning permissions to be obtained at the end of the work?

If you have made an extension to your house subject to prior declaration or building permit, you are not freed from administrative constraints on completion of the work.

You must

with the building permit issued or the non-opposition to the prior declaration

.

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Here's the procedure to follow :

• Download the

  Declaration Attesting to the Completion and Compliance of the Works

  (Cerfa form 13408*06), called

  Daact

  .

• Complete the document, and specify whether you are within the framework of a declaration of partial or total completion of the extension work.

• Attach the requested documents, depending on your project (the list appears on the Cerfa document).

• Send the Daact to your town hall: electronically according to the procedures defined by your municipality.

  By paper, by registered letter with request for acknowledgment of postal receipt to the mayor of the municipality.

  or deposited against discharge at the town hall.

From the receipt of the declaration at the town hall, the Administration has a period of

to contest the conformity of the works with the permit or the prior declaration.

After this period, the town hall can no longer contest the conformity of the work.

What do you risk in the event of extension work being carried out without the necessary authorisation?

Carrying out house extension work without a prior declaration or building permit is not a good idea.

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In the context of unauthorized work, the owner of the house can:

• See the demolished extension.

• Be ordered to pay a fine of between 1,200 euros and an amount that cannot exceed 300,000 euros.

• In the event of a repeat offence, in addition to the fine imposed, be sentenced to a prison term of 6 months.

Do I have to declare the extension to taxes?

As soon as you increase the living space of your home, you must send a

.

The work has an impact on the calculation of the property tax and the housing tax.

They may also lead to the payment of a development tax.

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You must complete and send form No. 6704 model IL and file the declaration within 90 days of the completion of the extension work.

How much expansion can be done without a building permit?

If the total area of ​​the planned extension work is

before you start the work.

How do I know if I have the right to make an extension?

To be certain that you comply with all the town planning authorizations required, but also with the PLU, do not hesitate to inquire with the town planning department of your city's town hall.

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Do you need an architect for a house extension?

As soon as the house extension covers a floor area of ​​more than 150 m2 after work, the use of an architect is not mandatory

.

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Conversely

, the use of an architect is mandatory when the planned floor area covers more than 150 m2.

If you live in a safeguarded or protected area, the extension project will be subject to additional authorization from the Architecte des Bâtiments de France.

Good to know

Even if the architect is not required by law, you can perfectly call on this building professional to help you draw up the plans for your extension project or to find out about the feasibility of your extension.

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