planning to build from scratch on a plot.
From the 1st January 2012 it has been permissible to construct an extension of up to 40m²
without the need to submit a planning application (permis de construire). It is still necessary to
submit a works declaration (déclaration préalable de travaux).
The change only applies to extensions to existing buildings; new and separate construction,
such as a detached garage or workshop, will continue to require a planning application.
A plan of the proposed works is still required. Although the process is quicker, approval of a
works application is not automatic; it will still have to comply with local planning and building
Reasons for refusal can include a lack of suitable infrastructure, non-respect of distances
between properties, architectural or landscape reasons, limits on the plot ratio (COS).
If the property is not within an area designated for construction by a local plan (PLU or POS)
then it will still be necessary to submit a planning application.
If the extension increases the floor area of an existing residential property to over 170m² then
a planning application will still need to be submitted and the use of an architect will continue to
be necessary. It appears that if the property already exceeds 170m² then existing rules apply,
including mandatory use of an architect.
Also the government has decided to simplify the calculation of habitable space within a
Up to the 29th February 2012 the terms 'SHOB' (Surface Hors Oeuvre Brute) and 'SHON'
(Surface Hors Oeuvre Nette) were used to define the different surface areas of a property.
From the 1st March 2012 there is a single, unified definition, called the 'surface de plancher'.
The new space definition is the surface area of the internal floors with a height of at least
1.80m. Apart from simplification of the calculation it is hoped to encourage construction of
energy efficient thicker walls which were penalized under the old system. It is also estimated
the change will increase the density of buildings on plots by about 10%.
Do not confuse the surface de plancher with the surface habitable seen on estate agent’s
particulars. The latter also has a legal definition and it excludes as well as internal walls,
partitions, stairs and stairwells, ducts, doorways and windows.
There is likely to be even more good news to come; at the time of writing it is still being
debated. The proposal is to increase the COS by 30% which for example would mean that a
plot of 1000m² with a COS of 0,2 could hold a dwelling with a surface de plancher of 260m² as
opposed to the existing 200m². The debate is over whether to exclude certain “protected zones”
and give Communes the right to opt out.