Hello all, we have bought a property with two shops on the ground floor. We’d like to change them to ground floor flats. Do we need planning to do this? We are not looking to change the facade. Is this a simple mairie visit or more? What do you think? The shops are not restricted in their use and would be part of a commercial enterprise as we are doing flats above.
Thank you 
There is a useful reference here.
Your best place to start is at the mairie - you will need the maire on-side in the first place anyway and they will give you invaluable initial guidance as to what is required.
It really depends where they are and what the local plan says. It some places they are resisting the loss of commercial premises and it will be difficult, in other they are encouraging residential use and will bite your hand off to help you.
This gives you more information about change of use of commercial premises. Sometimes it is better to look at French references, as things like French Entrée don’ update their pages regularly.
You need a permit, which is 12 pages long and if you are lucky, the secretary of the mairie will help you. You will be confronted with the full paperwork the French have, to discourage any changes to their infrastructure.
But you are not the only one going through this and you better take it with humour, because it takes time and nerves.
No. You only need to do the full permis de construction if you are also doing works. For a change of use it is simply a déclaration préalable as long as a change of use is permitted in the local plan.
However if the transformation that goes ahead requires building work you will need a permis for the works, and if over 150m2 an architect.
Thank you all for your replies. We have contacted the mairie and will see how we go. Thanks again