A veranda is the most tempting addition to a French house. It is the room you sit in during March and October, when the garden is too cold and the house feels shut in. It adds light, it adds space, and compared with a proper extension it looks cheap.
It is also, in planning terms, an extension like any other. The French administration does not see a glass box. It sees new floor area, and new floor area brings formalities, thresholds, and two separate taxes that catch people out long after the glazing is in.
None of this should stop you. But it is a great deal better known before you order than discovered afterwards.
The surface decides everything
Forget what the veranda is made of. The only number that matters is the floor area it creates, and there are four bands.
Up to 5 square metres: no formality at all. Small, but real — a little lean-to porch can fit.
From 5 to 20 square metres: a déclaration préalable. This is the lighter of the two planning applications, it takes about a month, and it applies everywhere in France.
From 20 to 40 square metres: it depends where you live. If your house sits in a zone marked U on the commune's PLU — the urban zone, which is most villages and towns with a local plan — the déclaration préalable stretches up to 40 square metres. If your commune has no PLU, or your house is in an A, N or AU zone, the limit stays at 20 and anything above it needs a full permit.
Over 40 square metres: a permis de construire, every time, about two months.
That 40-square-metre band is the single most useful thing to know, and the single most commonly got wrong. It is not a national rule you can rely on. It depends on the letter attached to your plot in the local plan, and finding that letter is the first thing to do, before you ring a single supplier. We set out how to read a PLU and find your zone in fences and hedges in France — the method is the same whatever you are building.
The architect threshold nobody mentions
Here is the trap that turns a straightforward project into an expensive one.
If your veranda needs a permis de construire, and the total floor area of the house after the work comes to more than 150 square metres, you must engage an architect. Not an optional extra — a legal requirement, and the application will not be accepted without the signature.
Work the sum before you choose a size. A 140-square-metre house with a 25-square-metre veranda arrives at 165, and you have just bought yourself an architect's fee on top of the glazing. The same house with an 18-square-metre veranda stays inside a déclaration préalable in a U zone, needs no architect, and costs a great deal less in paperwork.
That is not a reason to build something too small to enjoy. It is a reason to decide the size with the thresholds in front of you rather than from a brochure.
One footnote worth knowing: if the property is held through a company rather than in your own name — an SCI, for instance — the 150-square-metre exemption does not apply at all, and an architect is required from the first square metre under a permit.
Heated or unheated changes what it is
A veranda counts as floor area for planning whether or not you heat it. Closed, covered, over 1.80 metres high: it counts.
But heating changes what it becomes afterwards. An unheated veranda is not habitable space — it stays out of the surface habitable figure used for a lease and quoted on the energy certificate. Put a radiator or a heated floor in it and it becomes living space, and it has to meet the thermal requirements that come with that.
This matters more than the paperwork suggests. A glazed room is a glorious thing in spring and a liability in August and January if it is built as a greenhouse. If you intend to use it all year, it needs the glazing specification, the ventilation and the shading to make that possible, and those are decisions taken at the quotation stage, not later. We go into how a modern French house is built to handle heat and cold in RE2020 explained.
The first tax: taxe d'aménagement
Every square metre you create carries a one-off development tax. It is calculated in a way that looks complicated and is not.
The state sets a national value per square metre each year. For 2026 that is 892 euros outside the Paris region, and 1,011 euros within it — both down slightly on 2025. Your commune then applies its own rate, somewhere between 1 and 5 per cent, and the department adds up to 2.5 per cent on top.
The relief is generous and people forget to count it: on a main residence, the first 100 square metres are halved. So an 18-square-metre veranda is taxed on nine.
Run the numbers on that example, with a commune at 4 per cent and a department at 1.5: nine square metres at 892 euros, at five and a half per cent in total, comes to a little over 440 euros. Not nothing, but not the horror story it is sometimes made out to be either. Ask at the mairie what the two rates are in your commune before you budget — they vary, and the difference between a 1 per cent commune and a 5 per cent one is real money.
The bill arrives from 90 days after the work is finished.
The second tax: what it does to your taxe foncière
This is the one that keeps costing you.
A veranda raises the rateable value of the house, and therefore your annual taxe foncière, for as long as you own it. How much depends entirely on the commune and the house, but it is an annual figure rather than a one-off, and it should be in your thinking before you commit.
There is a genuine piece of good news attached, and it has a deadline on it. You must declare the completed work within 90 days, through the "Gérer mes biens immobiliers" section of your account at impots.gouv.fr. Declare it on time and new construction qualifies for a two-year exemption from the communal part of the taxe foncière. Miss the 90 days and you lose the exemption and invite a penalty — for a form that takes twenty minutes.
Put the date in the diary the week the builders leave. It is the cheapest money you will make all year.
The wider picture of what a French house costs to run each year is in the annual cost of owning a house in France.
What the local plan can still refuse you
Meeting the surface thresholds gets you the right to apply. It does not get you a yes.
The PLU can dictate the appearance: the pitch of the roof, the colour of the frames, the materials, whether glazing is permitted on that elevation at all. Many rural communes are relaxed. Some are not, and a village with protected character can be very particular indeed about an aluminium structure on a stone façade.
There are three further layers to check. If the house sits within the protected surroundings of a listed building — commonly a 500-metre radius, though some communes have a specific delimited zone — the application goes past the architecte des bâtiments de France, and their opinion is binding in practice. If the house is on a lotissement, the estate's own cahier des charges may impose rules stricter than the commune's, and it binds you privately whatever the mairie says. And if the property is in a copropriété, the veranda usually alters the common appearance of the building and needs a vote at the general meeting.
None of these are discovered by looking at your own garden. All three are discovered by asking.
Boundaries and your neighbour
A veranda is a building, so it must respect the setbacks in the PLU — typically either built hard against the boundary or set back at least three metres, with the local plan deciding which.
There is also a rule about windows that applies to glazing as it does to any other opening, and it is worth raising before you site the thing rather than after a complaint. An opening that looks directly onto a neighbour's land must be at least 1.9 metres from the boundary; one that only looks obliquely must be at least 60 centimetres. A veranda built in the wrong corner of a plot can create a direct view where none existed, and that is the sort of thing that sours a relationship for twenty years.
Who should build it
Whoever fits your veranda must carry décennale insurance — the ten-year structural cover that is compulsory for building work in France. Ask for the attestation and look at the date on it before you pay a deposit. A veranda bolted to the house affects the fabric of the house, and if it leaks into the wall three years later you will want that cover to exist.
Be wary, too, of the firm that tells you no permission is needed because the structure is "demountable". If it is closed, covered and over 1.80 metres high, it counts, and the fact that it could in principle be taken down again does not interest the mairie.
What we would say
The order of work is the thing. Find your zone on the PLU first. Add the veranda to the existing floor area and see whether the total crosses 150. Ask the mairie for the two tax rates. Then decide the size, and then talk to suppliers.
Do it that way round and a veranda is one of the best-value things you can add to a French house. Do it the other way round and you discover the architect, the ABF and the tax bill one at a time, each of them after you have already committed.
If you are building with us, the sensible moment to put a veranda in is at the same time as the house — the slab, the drainage and the electrics are all open, the planning goes in as one application, and it costs considerably less than coming back to it in three years. Book a free half-hour and tell us what you have in mind, and we will tell you what your plot and your local plan will actually allow. You can also reach us on WhatsApp or by email for a same-day answer.