Geological report in Italy: when you need one and what it costs

You need one when the project includes works that bear on the ground: the foundations of a new house, retaining walls, excavation, strengthening existing foundations, work on a slope. Italy’s 2018 technical building standards (NTC, chapter 6) make the relazione geologica an integral part of the design, separate from the geotechnical report. Professional fee scales were abolished in 2012: the price depends on the site investigations, and the professional must quote it in writing before starting.

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When the standards require it

Italy’s technical building standards, the Norme tecniche per le costruzioni of 2018 (NTC, Ministerial Decree of 17 January 2018), devote chapter 6 to works that bear on the ground: foundations, retaining structures, underground works, earth structures, excavation faces, ground improvement and the strengthening of existing structures. The chapter also covers the stability of natural slopes.

For these works, the results of the geological study of the site, «drawn from specific investigations», must be set out in a relazione geologica, a geological report (section 6.1.2). Section 6.2.1 adds that the report «is an integral part of the design»: it is not an optional extra produced only if the comune asks.

A new house on agricultural or building land always has foundations, so it is covered. So is an extension, a retaining wall on a sloping plot or digging out a basement. Work that does not touch the ground, such as wiring or finishes, does not raise the question.

The standards lay the design out in a fixed order, summarised in the diagram below. Geology comes first, and the geological model is what the designer uses to frame the ground problems and decide which tests to run.

Sources: NTC 2018, chapter 6; accessed 13 November 2026.

Geological report and geotechnical report

They are two different documents, and your quote should say which one it covers.

The geological report builds the site’s geological model: the formations present, rock and soil types, the structure of the subsoil, groundwater, landforms and the geological hazards that follow from them. Which investigations are needed depends on the type of work and on how complex the local geology is; the standards set no fixed package.

The geotechnical report (relazione geotecnica) starts from that model and turns to numbers: the test programme and results, the geotechnical ground model, the calculations that size the foundations, the construction stages (section 6.1.2). Geotechnical tests cover the volume significativo, the ground affected by the building and affecting it in turn. The designer is responsible for the test plan, the ground description and the geotechnical model (section 6.2.2).

Laboratory tests on soil and rock are carried out and certified by laboratories authorised under Article 59 of DPR 380/2001, listed with the Central Technical Service of the Higher Council of Public Works.

Who signs it

Commission a qualified geologo registered in section A for the geological report on civil engineering works (DPR 328/2001, Article 41(1)(c)). Check the territorial Ordine professional register and the competence for the assignment. Law 112/1963 preserves other statutory professional powers; anyone relying on them must identify the specific legal basis.

The exception for minor works

Section 6.2.2 allows a lighter route: for minor buildings or works in areas whose ground is well known from a geotechnical point of view, the design may rely on existing documented investigations and tests, with the designer still fully responsible for assumptions and choices.

Both conditions must hold, and neither comes with a number: the standards do not say how many square or cubic metres make a work minor. The designer decides, signs the design and answers for it. The passage concerns geotechnical investigations; it does not remove the geological report from the design.

Ask the designer which existing investigations will be used and why they represent the ground affected by your particular works. If the designer proposes to rely on existing tests, ask which ones, where they were done and how far from your plot.

Investigations: what happens on site

Investigations look at the ground where the building will stand. Public price lists include penetration tests, which measure how hard it is to push a probe down through the soil, undisturbed sampling, the SPT, vane and pressuremeter tests, and boreholes fitted with a piezometer to read the water level. In the laboratory, samples are tested for grain size, Atterberg limits, water content and shear strength.

The investigations themselves, when they are temporary geotechnical exploration works outside the built-up centre, need no building permit (DPR 380/2001, Article 6, paragraph 1, letter c). The comune’s plan, seismic rules, hydrogeological rules and the Cultural Heritage and Landscape Code still apply.

On someone else’s land, however, nobody drills without the owner’s consent. If you want tests before completion, the preliminary contract (the compromesso signed before the deed) should say who carries them out, who pays and by when. How to word that kind of condition is explained in the guide to the conditional preliminary contract.

What it costs and what drives the price

Since 2012 the fee scales of the regulated professions have been abolished and the fee is agreed when the job is given (Decree-Law 1/2012, Article 9). The professional must tell you in writing how complex the job is and give a written estimate listing, for each service, every cost item, including expenses, charges and contributions (paragraph 4).

The bill grows with the number of tests, their type, their depth and the laboratory work. For a sense of unit prices you can look at a regional price list for public works, which applies to public contracts and is not a price list for private clients. The chart uses the Friuli Venezia Giulia 2025 list for laboratory tests, priced per sample; the table below has the field tests, priced per metre.

Sources: FVG price list 2025, item 11.2.UD2; Decree-Law 1/2012, Article 9; accessed 13 November 2026.

The public data a geologist reads

Before drilling, a geologist reads what is already published. The main sources are national and free to consult.

• Geological Map of Italy at 1:50,000 (ISPRA’s CARG project). The project needs 636 sheets to cover the country; according to ISPRA, 281 geological sheets, about 44% of the coverage, and 32 thematic sheets have been produced. Where a sheet is missing, older or regional maps are used.
• Italian Landslide Inventory (IFFI) and the IdroGEO platform. Compiled by ISPRA with the regions, autonomous provinces and regional environment agencies, it records over 635,000 landslides covering 24,700 km², 8.2% of the country (ISPRA presentation of 11 December 2024).
• Hydrogeological plans (PAI). In 2024 landslide hazard areas in the PAI plans covered 69,500 km², 23% of Italy, against 55,400 km² in 2021; ISPRA puts the increase mainly down to more detailed studies. How to read them is in the guide to flood and landslide risk in the PAI.
• Seismic classification and microzoning. Seismic zones are set by the regions after consulting provinces and comuni (DPR 380/2001, Article 83); some use four zones, others three or sub-zones, so the meaning is in the regional rules. Microzoning studies separate stable zones, stable zones where shaking may be amplified and unstable zones prone to landslides, faulting or liquefaction. What the zones mean for a buyer is in the guide to seismic zones.
• ISPRA archive of subsurface investigations (Law 464/1984). It holds records of investigations, mostly deep ones, with depth and, where available, stratigraphy and water data.

In seismic areas the design is filed with the comune’s one-stop desk, which passes it to the region’s technical office; that office sets the minimum content, and the design comes with the documents required by the technical standards (DPR 380/2001, Article 93). If the land is also under the hydrogeological constraint, the works need a separate clearance, explained in the guide to the hydrogeological constraint.

Before you buy: what to ask, and whom

1. Before the offer, on the public portals. Look the parcel up on IdroGEO, the river basin authority’s PAI maps and the region’s seismic classification, and note zones and distances.
2. Before the offer, with a geologist. Ask for a first reading of public data and existing investigations nearby, and whether the house you have in mind will need extensive testing. The geologist’s estimate gives the time and cost of that reading.
3. At the comune’s planning office or building desk. Ask for the certificato di destinazione urbanistica (CDU, the zoning certificate) and whether the town plan includes geological studies for that zone.
4. In the preliminary contract. If building is the reason for the purchase, write down who runs the tests, by when, and what happens if the results make the project too costly.
5. Before the deed. Make sure the reports paid for during negotiations are in your name, or that you have permission to use them.