How can you tell whether a house is in a flood zone before buying?
Enter the address on Géorisques: the page shows whether it lies within a flood risk prevention plan (PPRi), a territory at significant flood risk (TRI) or a flood zone atlas. Only an adopted PPRi is a servitude that governs building; the other maps inform. The seller must then give you the state-of-risks report from the first viewing, and the mairie (town hall) tells you which rules apply to the plot.
The four sources to know
In France, flood information does not fit on one map. Each document has a different status, and that status is what matters to a buyer.
| Document | What it shows | Legal effect |
|---|---|---|
| PPRi (flood risk prevention plan) | Regulatory zones, often red and blue, with rules | Public-interest servitude annexed to the PLU |
| TRI (territory at significant flood risk) | Flood extents for a frequent, medium and exceptional event | Information, not a servitude |
| AZI (flood zone atlas) | The highest known water levels, often from past floods | Information, not a servitude |
| Natural disaster orders (catnat) | Floods recognised in the commune, with their date | History that matters for insurance |
TRI maps distinguish three scenarios: a frequent event (return period of 10 to 30 years), a medium event (at least a 100-year flood, often the reference flood of the PPRs) and an exceptional event, around a 1,000-year flood. Their accuracy is about 1:25,000: they do not settle things to the metre.
Other data often matter for the same house, such as clay shrink-swell and the state-of-risks report. You can see how a dossier sets them out register by register in the sample dossier.
How to check an address step by step
- On Géorisques, under 'Know the risks near me', enter the address and read the flood section: PPR, TRI, AZI and natural disaster orders.
- If a PPRi exists, ask the mairie or consult the PLU to read the rules of the zone the plot is in, not just the colour on the map.
- Ask the seller for the state-of-risks report and check that it is less than six months old.
- Ask the seller whether they have ever been compensated after a flood: the state-of-risks report must list claims paid out under a natural disaster order.
- Look at the site: ground-floor level, basement, water marks, closeness to a river or ditch.
What a PPR can require of a house
A natural risk prevention plan is drawn up by the State (art. L562-1 of the Environment Code). In the most exposed zones it can prohibit new building; elsewhere it can allow it under conditions, for example a floor above the reference flood level or no basements. It can also require measures for existing buildings, such as a refuge area or non-return valves.
For an existing building these mandatory works remain limited: their cost cannot exceed 10% of the market value of the property (art. R562-5 of the same code). The state-of-risks report says whether the rules require works for the property and whether they have been done: a precise question to put to the seller. For an extension or rebuilding, only the planning department of the mairie says what is allowed in the zone.
The PLU zones and what they allow
Insurance, price and timing
A house in a flood zone remains insurable: natural disaster cover is part of the home insurance policy, and it applies when an order recognises a natural disaster. Ask for an insurance quote before you sign, giving the exact address.
Risk also shows in the price. Compare with actual sales in the street and in higher neighbouring streets: a gap may reflect the exposure, or something else. If the state-of-risks report reaches you after the compromis is signed, the ten-day cooling-off period (art. L271-1 of the Construction and Housing Code) only starts the day after you receive it.
Reading actual sale prices (DVF)
For one address, ScanAdresse brings together the Géorisques hazards (including flooding and natural disaster orders), the PLU zone and the servitudes, with found, not found or source unreachable for each register; the preview is free and the dossier costs €29 including VAT.
Frequently asked questions
Does a blue PPRi zone stop you buying?
No. The PPRi governs building and works, not sales. In a blue zone, building is usually allowed under conditions; what you may do on the plot is in the rules, and the mairie assesses it when you apply for consent.
Can a house outside the maps flood?
Yes. The maps show scenarios and known floods at a limited scale. Surface run-off, rising groundwater or a blocked ditch can affect a house outside any zone. Ask the seller and the neighbours.
Must the seller say if the house has flooded?
The state-of-risks report must list claims paid after a natural disaster order. For anything else, ask in writing before the compromis; in a dispute, a lawyer or the court assesses it.
Is the PPRi part of the PLU?
An adopted PPR is a public-interest servitude and must be annexed to the PLU. It applies on top of the rules of the PLU zone.
Sources
- Géorisques: floods
- Géorisques: risks near me
- Service-public.fr: state-of-risks report
- Environment Code, art. L562-1 and R562-5
- Construction and Housing Code, art. L271-1
ScanAdresse is a private service by SRI Group BV (VAT BE1037052239), not connected to any public authority: it brings together public data, with the source and date of every item.
Updated on