The prior declaration of works sufficient for extensions of up to 20 m² is being extended. Indeed, as of 1 January 2012 this simplified approach will apply to area of up to 40 m² that is covered by a PLU or planning document. When this is not the case, the limit is 20 m².
Beware: a building permit is required when as a result of the extension the total area of the construction ends up being more than 170 m², if this threshold is reached the services of an architect are compulsory.
The drilling of an outside wall resulting in changes to the volume of an existing building will not be subject to building permits. This applies no matter what the surface area created is.
Source: Decree No. 2011 – 1771 December 5, 2011 on the formalities required to carry out works on existing buildings, OJ of December 7
Floor surface area
The rule applicable to surface area measurement in Urban Law has been simplified. So far, you should refer to the gross floor area (SHOB) and the net floor area (SHON).
The order of 16 November 2011 introduces the new single definition of the surface area applicable under Urban Law: « the total amount of the floor surface area closed and covered, under a ceiling height of more than 1.80 metre, calculated from the bare inside of the facades of the building.
The thickness of the walls is therefore no more taken into account, and as a result the efforts to insulate both the inside and the outside of the building are not penalised.
These measures came into force on March 1, 2012.
Finally, this new floor surface space sets the basis to the new local planning tax that replaces the TLE (local equipment tax) and the tax for the CAUE since March 1, 2012.
Source: Order No. 2011-1539 November 16, 2011 on the definition of floor surfaces taken into account in planning law, OJ of November 17