PAI flood and landslide risk in Italy: before you buy

PAI maps identify hazardous areas and land-use rules: before buying, check the parcel’s class and the provisions affecting your intended project.

Already have a parcel in mind? The report runs these checks on your land, with a source and date for every finding: €29 in English or Italian · €39 in both languages. Find it on the map →

What is the PAI and why does it matter when buying?

Save the map sheet with its legend, date and reference to the adopting decision. A screenshot without those details makes it difficult to establish whether its colours belong to the effective map or an earlier version.

PAI plans belong to the basin planning framework now managed by the Autorità di bacino distrettuali (district basin authorities). Legislative Decree 152/2006, current text, Articles 65–68 provides the framework: read the map together with its rules. Land zoned for building in the town plan is still bound by the basin plan’s rules and safeguard measures.

Describe the intended use: cultivating an olive grove differs from converting a farmhouse or excavating a pool. Even if the house is outside the boundary, access and utility works may cross it. Check the whole proposal.

The practical order is: identify every parcel, look at IdroGEO, read the district maps and NTA rules, ask the Comune for the CDU and geological maps, have a geologist assess the project, and only then talk about a deposit with the lender and the notary.

Be careful: a signed offer, once accepted, can already bind you, so make these checks before signing it or write them into the offer as conditions. The section “How do you check a parcel on IdroGEO and local maps?” walks through each step.

TerrenoCheck’s preliminary risk report organises public sources and questions for professionals. It is an initial review, not a professional opinion, and does not certify ownership, title or the right to build. Use the buying land in Italy checklist to organise the rest of the purchase file alongside these hazard checks.

What do landslide P3 and flood hazard P2 mean?

P describes pericolosità (hazard); R describes rischio (risk, including the consequences for exposed people and assets). Always identify the map subject: landslide and flood ladders are different classification systems.

For landslides, ISPRA’s national PAI mosaic harmonises P1 moderate, P2 medium, P3 high and P4 very high hazard, with AA attention areas alongside them. Local maps may use other codes or subdivisions. Use the local legend to interpret the designation and find its rule.

For floods, P1 denotes low probability, P2 medium probability and P3 high probability. Legislative Decree 49/2010, Article 6 distinguishes rare, less frequent and frequent events. Flood maps should also describe the extent and depth or level of water, together with flow characteristics. Colour alone does not explain a basement’s exposure or whether the access road would remain usable.

Risk classes R1 moderate, R2 medium, R3 high and R4 very high combine the physical event with what could be harmed, within the framework referenced by Article 6 of Legislative Decree 49/2010. An empty field may have few exposed assets, and so a low risk class, even in a hazardous area. Build a house there and the risk rises: today’s R1 is not permission for a new home.

The ISPRA national figures at the top of this page show the scale of the issue, not the probability of damage to your house, and the landslide and flood figures must not be added together.

Source: TerrenoCheck, conceptual diagram

How do PAI, PGRA and vincolo idrogeologico differ?

PGRA addresses flood risk management; vincolo idrogeologico (a soil and water protection constraint) regulates certain changes to land. These are separate checks from landslide PAI and seismic classification: a favourable answer on one does not resolve the others.

The Piano di Gestione del Rischio di Alluvioni (PGRA, flood risk management plan) derives from Directive 2007/60/EC, implemented in Italy by Legislative Decree 49/2010. It connects maps to prevention and management. Ask which PGRA, hydraulic PAI and regional rules operate together locally.

The vincolo idrogeologico under Royal Decree 3267/1923 is not a PAI class. It protects land against uses that could promote erosion or instability and disturb water regimes. It is not confined to woodland. Siena Municipality’s Hydrogeological constraint service illustrates the link with regional forestry legislation and authorisation. That is a Tuscan example, rather than a procedure applied identically nationwide.

Tuscany’s Geoscopio hydrogeological constraint metadata distinguishes decree-based boundaries from an indicative woodland inventory, explaining the latter’s limitations. For vegetated land, also consult the guide to woodland and permitted alterations. A PAI result does not settle forestry questions.

Can you build on land with a PAI designation?

The answer depends on the applicable norme di attuazione (NTA, implementation rules) and the precise category of work. Higher hazard classes can carry severe restrictions on new development; maintenance, refurbishment and hazard-reduction works have their own conditions.

Have the designer classify the proposal before looking for a favourable provision. “Restoring the farmhouse” might mean repairing a roof or demolition and reconstruction with an extension. Even municipally permitted work must meet applicable basin planning requirements. The guide to PRG, PUC and building rights helps assemble that wider planning check.

Safeguards apply to specified NTA provisions: AUBAC resolution 68/2026, Article 3, landslides and AUBAC resolution 67/2026, Article 3, hydraulics. Have the professional reconcile new prohibitions with earlier rules governing permitted works.

Landslide example: AUBAC landslide PAI NTA, Articles 9 and 10 prohibit private new buildings and extensions in P4 and P3 as specified; P4 also prohibits ristrutturazione edilizia (major renovation that can change the building). Defined works, including conditional maintenance, remain possible through the relevant routes. An estate listing’s word “restoration” does not identify an authorised category.

Flood example: AUBAC hydraulic PAI NTA, Article 9 prohibits P3 private new buildings and extensions outside the existing envelope, subject to exceptions, and new underground or semi-basement volumes. Mapped marginal areas have specific treatment; maintenance and other conditional works are provided for. Raising a floor alone cannot override a prohibition.

A private report can document local conditions and support an application, but does not itself amend the official boundary. Where a seller says the map is outdated following stabilisation works, request the final decision and updated mapping. A promise that “you only need to apply to remove the designation” leaves an uncertain administrative outcome with the buyer.

How do you check a parcel on IdroGEO and local maps?

Use IdroGEO to identify the issue, then compare the full parcel with the competent authority’s maps and rules. Complete the check through the regional geoportal, the municipal planning certificate and the geological maps of the local plan.

Obtain the comune catastale (cadastral municipality), any section, foglio (map sheet) and particella (parcel number). Include every parcel in the sale and the building. A rural address can place a pin in the wrong courtyard. Compare the cadastral extract with recognisable features. If the land was recently subdivided (frazionamento), get the new parcel numbers from the seller and check them against the listing before you look at any map.

On ISPRA’s IdroGEO, examine landslide hazard, flood hazard and the IFFI landslide inventory separately. ISPRA’s Introduction to IdroGEO describes searching and querying. IFFI, the Inventario dei Fenomeni Franosi in Italia (Italian landslide inventory), records mapped phenomena. A nearby inventory record and an intersecting PAI hazard boundary are different findings.

Italy has seven river-basin districts, listed in Article 64 of Legislative Decree 152/2006: Eastern Alps, Po, Northern, Central and Southern Apennines, Sardinia and Sicily. The regional geoportal shows which one covers the municipality; then open that basin authority’s map viewer.

For the Central Apennines, AUBAC’s District PAI presentation links its Digital Twin, maps and adopted texts. In another district use that district’s portal and legend. Check amendments and safeguards which may not yet appear in the national view.

On the regional geoportal, look for information relevant to the site, including local studies where available. Ask the Comune (municipality) for the certificato di destinazione urbanistica (CDU, planning designation certificate) and the geological and geomorphological studies behind its planning instrument, including the map of feasibility classes (carta della fattibilità) where the region requires one.

The CDU certificate guide explains how it fits into the purchase file. An omitted PAI reference in the certificate does not close the basin-map check.

In the Diano San Pietro sample report the summary page sets several results side by side: a P1 landslide area on the parcel, no flood area of the district plans (the nearest P3 is 177 m away) and the nearest landslide recorded in the national IFFI inventory 1.5 km away.

The next step it names is a geologist’s report. It is an example, not an assessment of a property for sale: do not judge another slope from it.

What should you ask a geologist before buying in a PAI area?

Request an assessment tied to the parcel and intended use, with a site visit and a clear statement of further investigations needed. A useful answer distinguishes map-based findings from questions requiring investigation or confirmation from the responsible office.

Give the geologist the designer’s file, the seller’s studies and protective-work records. Agree scope, quotation and timetable: an initial map review differs from a project report. There is no standard national fee covering every case: get the quotation and the delivery date in writing before the offer, so the deadline in your condition also covers the report.

At the site visit, flag cracks, distorted walls, standing water and erosion without diagnosing them. Include the slope beyond the boundary: uphill excavation or water can affect the property. For floods, have ground and entrance levels compared with potential water routes and access conditions.

A wall or ditch does not prove adequate protection. Request designs, consents and maintenance records. If a proposed solution depends on works on somebody else’s land, ask the technical professional and notary how access rights and responsibilities can be checked before treating that solution as achievable.

How does PAI affect mortgages, insurance and the deposit?

A PAI class can affect project feasibility, valuation and insurance terms. It does not by itself establish mortgage refusal or a standard price discount: obtain answers for the actual property and transaction before committing money.

If you are buying with a mortgage, talk to the lender before you sign an offer and send the technical findings as soon as you have them. Banca d’Italia’s Mortgage guide distinguishes property valuation from the lending decision. Ask which documents the valuer needs, which project the valuation assumes and what must be resolved before funds are released.

For insurance, disclose the location and actual use and request written terms. Compare the definitions of flood and landslide, exclusions, the excess and indemnity limits. IVASS’s Second survey of catastrophe-risk policies, June 2026 examines coverage differences and clarity. Read the conditions governing a claim.

Before negotiating price, budget for necessary works, future maintenance and access after an event. If the rules exclude your intended project, a discount does not resolve that incompatibility.

A signed proposta d’acquisto (purchase offer), once accepted and with acceptance communicated within the relevant terms, can already bind the parties (Civil Code, Article 1326).

Before signing, agree with the notary and your technical professional which project is to be checked, on what evidence, by what date, and what happens to the money if the answer is negative. Avoid an undefined “subject to checks”. If already signed, have the agreement examined without assuming automatic return of the caparra (contractual deposit); the guide to the preliminary contract and deposit covers commitments and money paid.

Checks in order, before the deposit

1. Identify every parcel and building in the sale and describe to the technician the use and works you are buying for.
2. Check IdroGEO separately for landslides, floods and the IFFI inventory, saving the map, key, version and date.
3. Read the maps and rules of the competent district basin authority and the regional geoportal, with any safeguards in force.
4. Ask the Comune for the CDU and the geological maps of the municipal plan.
5. Have the geologist assess the project, with a site visit, over the whole parcel and the access.
6. Take the technical picture to the bank and the insurer and ask for answers on this property.
7. Write the condition tied to the technician’s answer, and what happens to the money, into the offer; before the deed, re-check maps and safeguards.

Sources: ISPRA, IdroGEO; Legislative Decree 152/2006; Civil Code, Article 1326; accessed 15 October 2026.

A page from a delivered report

Detail of page 33Open the full page

Source: TerrenoCheck, Diano San Pietro, parcel 444, p. 33