What is usually allowed on a plot?

Hello experienced self builders!

I am aware that the most obvious answer to this question will be “that completely depends on the plot” but I will ask anyway just in case anyone has some information about a rule of thumb :wink:

When you buy a plot of land with the intention of building a house, the planning permission needs to come from the local authorities, my questions are:

  • is it reasonable to expect that if you buy a house from a French builder/manufacturer, it should in principle comply with what is commonly seen as normal requirements the local authorities would have? I understand that if you intent to build a house that looks like a Spaceship in a traditional French village, you might run into some issues but as long as you purchase the house from a French chalet manufacturer, would it be safe to assume it will be accepted?

  • Is there a rule of thumb around what percentage of the size of the plot would be allowed to build on? Say you buy a 1000m2 plot of land, is it common to find that they usually accept houses of up to Xm2? And what about multiple small chalets?

Thanks in advance!

Hello Andre

In my experience, it does not pay to presume anything… the best thing is to discuss with the folk who control Urbanism. Areas differ widely and there might be all sorts of restraints/guidelines to follow.

Ask at your Mairie. They may be able to help you themselves but, if not, they will give you the right info of where to go and who to speak with re Planning/building.

Wait until you have the official permission to build, with all the t’s crossed and the i’s dotted - before you think about going ahead… and be sure to comply with all the requirements of the Permit. :hugs:

Just noticed you talking about multiple chalets - that is yet another ball game. Talk with the Planners/Urbanism folk, sounds like this would be a business venture ???


Hi Stella,

Yes indeed, I have a few options open to me but the one that has my preference is a plot of land of around 1000m2 with 1 larger wooden house of around 120m2 and 3 smaller chalets of around 50m2 to rent out. (We’d be lookig around the ski areas in Haute Savoie, Chamonix, St Gervais or Megeve). I’m wondering if a plot of 1000m2 is even something that could possibly allow for 4 builds. Heading down there in January and hoping to start a build in May.

thanks for your advice!

We’re looking at houses/chalets of this type:


It depends on the POS drawn up by the mairie and then the COS, and this varies from commune to commune. You need to talk to the mairie where you have the bit of land. A plot of 1000m2 with a COS of 0,35 allows one 350m2 building to be built. It depends on all sorts of things and there is no nation-wide rule.
POS is plan d’occupation des sols, ie what is building land at all.
COS is coefficient d’occupation des sols ie how big you can build on any given plot.

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Thank you Veronique! The COS is the thing I was unaware of, great to know that this is just a simple question I can ask the vendor to see if my plans are realistic.

I think if you have a COS of eg 0.5 on your 1000m2 plot, but you want to build 1x0.15 and 3x0.05 then you really need to talk to the mairie and they will tell you what is possible or not.

And now I come to think of it POS have been changed into PLU (plan local d’urbanisme) which may change something.
Bref it is a bit confusing and I hope I haven’t told you a load of out of date stuff! Talk to the mairie!

So POL/PLU is ok to plan a build when it’s described as “terrain a batir” or “viabilisé”?

I think the POS and now the PLU which replaced it recently are just the map of the commune with buildable areas marked on it, including the density etc. An actual permis de construire is delivered when your plan for something specific has been approved, then you have 3 years to get the work done or it lapses.
Terrain à batir means you can build on it and viabilisé means there is access and electricity water etc close by for connexion.

As I understand it (almost certainly incompletely), the PLU is the “new” (it isn’t really new, now, but replaces the old POS) designation for urban development in any given commune or group of communes, and it lays down the rules for the minimum/maximum urban density, the areas that are no-go building permit wise (risks, such as flooding, landslides, fires, earthquake, etc), and potentially the type and sizes of buildings that will be allowed dependent on the land use categorisation. Unfortunately, the PLU has to be voted and accepted by each and every commune affected by it in order to replace the old POSes (which were much more localised/specific to given communes). Some communes still haven’t got around to adopting/validating the new PLUs, which means that there can be somewhat of a legal vacuum as to the rules that actually apply. Sometimes a mairie will drag its feet in adopting a PLU because the conseil municipal doesn’t like it…This aspect of it I don’t really understand because I was under the impression that a particular commune affected by a grouped PLU didn’t really have any say in the matter…

In the previous village where I lived, for example, the PLU had been decided by the “regroupement de communes”, but for some reason (allegedly due to mayor of the village disagreeing with parts of the PLU) was never adopted by the conseil municipal. This meant that the village was relying on an outdated POS from about 15 years ago…shakes head in disbelief.

Yes, that happens! Foot dragging and obstruction, in the hope that something won’t be applied.

The only reason I learned any of this is because when it came to selling some land we owned in the village, the question was raised by the potential buyer…for which obviously I had no clue. Told the potential buyer to ask the mairie, the mairie stonewalled…

In the end it didn’t matter (for us), because the mairie bought the land under a “droit de préemption”.

I have to say that I was rather surprised at the proposed building density with which the first potential buyer wanted to develop the land - 6 or 8 >130m2 houses on 5000m2 land - seemed a bit tight to me !

Andre - fair enough to ask the Vendor - but, please, do not take whatever reply is given as gospel. The Mairie is the place to contact…

I know folk who mistakenly thought that existing buildings on a site, meant it was “building land”. Well, yes, it was to the degree that they could extend some of the existing buildings (by a percentage) - but they could not do the extra builds they had hoped for. They put the plot back on the market, but it took some years to sell… not a happy outcome.

(my heart sank when I read your post, seemed almost like déjà vu)

Had they checked with the Mairie, all the upset and disappointment (and expense) could have been avoided.


Terrible. I suppose it depends on where you are, in town or not but even so that is extremely cramped, you wouldn’t be allowed it in my commune.

That particular (rural) commune used to have a minimum 1000m2 plot requirement per house. Clearly that must have changed in recent years because a house got built round the corner on a plot of land of barely 200m2 - it is what the neighbours all disparagingly called a “boite à sucre”.

Our house stands on a plot that precisely corresponds to the footprint of the house, with not a millimetre to spare beyond any of its walls, on all point of the compass.

Even an emaciated termite would fail to get a foothold in its perimeters.

How did that get past the urban planners in the mid XIX Century?

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Ha ha… I suspect the roads were not quite as well defined as they are nowadays… :thinking:

In so many towns the houses/buildings are right onto the pavement…