Ex-Pat News

Friday Freebie – SHON, SHOB, COS… What?

morzine-property-agentEach week Sharon Scott of local estate agency 2 Valleys Properties shares a really useful, interesting and helpful guide to ex-pat life in the mountains. You’ll find the full back collection of Sharon’s blogs on our website, and on Sharon’s Facebook page.


This Week – SHON, SHOB, COS… What?

After a couple of Friday Freebie free weeks, I’m back! Today I will try and explain a bit about how to calculate the surface area of your house if you are thinking of applying for planning permission or a déclaration préalable.

From the 1st of March 2012, the terms and calculations ‘Surface de plancher’ and ’emprise au sol’ have replaced the old SHOB (surface hors-oeuvre brute) and SHON (surface hors-oeuvre net).

These calculations are very important if you are thinking of doing any building work or changes to your house or land and they are used by the tax office to calculate how much you have to pay in local taxes to the commune.

So what is the ‘Surface de plancher’ ?

It is equal to the sum of all the floor area of every level of a property closed and covered, calculated from the inside of the walls after the deduction of the following:

1. Any of the surfaces corresponding to the thickness of the walls surrounding any doorways and windows overlooking the exterior.

2. Any voids or space under stairways and lifts.

3. Any surface area with a distance under the ceiling  of less than 1.8m.

4. Any surface areas used for the parking of vehicles, including ramps and manoeuvring areas.

5. Any areas situated in the eaves of a house (attic space) that is not used as  living, professional, industrial or commercial space.

6. Any areas used as technical premises (i.e. where there is the electricity meter or water meter) necessary to the functioning of a group of buildings or a building other than an individual house, including any rubbish storage areas.

7. Surface areas of cellars, annex to the property used as communal space.

8. A 10% reduction can also be subtracted for any properties that have communal areas located in the interior of the building i.e an apartment in a building that shares a communal hallway.

So what is the ‘Emprise au sol?’

This is the vertical projection of the volume of construction, all eaves and over hangings included. The calculation of this is sometimes needed for the application of a permis de construire or a déclaration prélable as a compliment to the surface du plancher calculation, particularly if you are extending the property over and beyond its current footprint.

Do not confuse the rules concerning the emprise au sol with the COS, which represents the accumulated ‘surface de planchers’ of every level of the property and not the footprint.

How to calculate the ‘Emprise au sol’ maximum allowance for your property?

Example: You would like to extend your house which at the moment has an emprise au sol measurement of 40m2 on a plot of 256.5m2

The rule that applies to the particular zone says that you are limited to using 40% of the plot.

Therefore the maximum emprise au sol that can be used is calculated thus:

256.5 x 40 divided by 100 = 102.6m2

So the emprise au sol that can still be used is calculated thus:

102.6 – 40= 62.6m2

You can therefore build on upto 62.6m2 more of the plot

The Emprise au sol does not include decking or terraces on the ground level of a property or any outside parking spaces. Exterior access ramps are however included.

The COS: what is it?

The COS is the ‘coefficient d’occupation des sols’ or more simply it is the calculation used to work out how much of your land plot you are allowed to build on in relation to the overall surface du plancher. The COS will vary from one zone to another and from one commune to another. It is expressed as the percentage of the land that can be used for a construction in relation to the amount of ‘surface du plancher’ you have adding up all the floors of your house.

For example:

Land area = 1000m2 and the COS is 0.3

1000 x 0,3 gives 300m2

You can therefore build a property which will be 300m2 with all the floor levels combined i.e a house on 3 floors of 100m2.

I hope this has been of use to some of you. The rules in France change quite a lot and as previously mentioned, regulations vary from commune to commune and from zone to zone.

Click to comment

Leave a Reply

Your email address will not be published. Required fields are marked *

To Top