Carros: Clay Soil, Subsidence and Cracks – Official Data

Carros, clay and drought: what the official figures really say

Your house is cracking in Carros and you want to know whether it is linked to drought: the GASPAR database lists 3 drought natural disaster decrees (2005, 2023, 2024) and 11 flood decrees, i.e. 14 natural disaster declarations (Cat Nat). On the weather side, the finding fits: two rainfall-deficit years in 2021 and 2022, then a rebound to 1,248 mm in 2024 – precisely the scenario that puts foundations to work, in the village as in the new Les Plans district.

Cassini Expertise, an independent building expert, deals with cracks and drought-related damage in Carros and throughout the 06. This page brings together the commune’s official data, with no commercial angle, to help you determine whether your cracks are linked to the phenomenon and what to do next.

How many drought natural disaster decrees in Carros, and what use are they?

The GASPAR database (decrees published in the Official Gazette since 1982) lists 14 natural disaster decrees for the commune:

• 3 drought decrees (differential ground movement due to clay shrink-swell)
  • event of 01/07/2003 (decree of 27/05/2005)
  • event of 01/01/2022 (decree of 03/04/2023)
  • event of 31/12/2022 (decree of 23/09/2024)
• 11 flood and storm decrees

What to take from it in practical terms: if your cracks appeared during one of these three recognised periods, you can claim Cat Nat compensation – but only if you declared the claim to your insurer within 30 days of the decree. If you let that deadline pass, or if the damage predates your purchase of the property, there remains the route of latent defect or fraudulent misrepresentation against the seller (see below).

Is Carros in a risk clay zone? The official ranking

The GéoRisques platform (BRGM) classifies Carros at high exposure to clay shrink-swell (RGA), with some sectors at medium exposure. This is the level your insurer and your notaire already consult to assess the risk on your plot – you can carry out the same check free of charge on georisques.gouv.fr before buying or having works done.

This ranking complements the decree history above: the hazard tells you what can happen, the decrees tell you what has already happened. If your house is in a high-exposure area and has already been through one or more dry summers, the risk of damage is all the better documented – an argument to keep to hand in the event of a dispute or an insurance file.

The geological and climate context of Carros

Carros is a commune of contrasting faces: the old perched village dominates the Var valley, while the industrial zone and the residential estates have developed below and on the hillsides, between La Grave and Les Plans. It is precisely this topographical diversity that creates risk situations for buildings. On the south-facing clay slopes, the Mediterranean vegetation – Aleppo pines, holm oaks, olive trees – pumps water from deep in the soil during the summer, accentuating the shrinkage of the clay beneath the shallow foundations of villas built in the 1970s-80s, at a time when soil surveys were not systematic. The more recent constructions, from the estates of the 2000s on ground reworked with cut and fill, are not spared either: compaction heterogeneities favour differential settlement from the first markedly dry periods. We are regularly called out to Provençal houses in the La Collette or Le Moulin area, where stair-step cracks on façade corners betray this movement of expansive clay that shrinks in summer and swells again with the autumn rains. The pronounced relief of Carros, with its sloping ground often requiring retaining walls and asymmetrical foundations, further aggravates the vulnerability of many homes to these cycles of soil desiccation and rehydration.

Rainfall: the commune’s long memory

The weather archives for the area cover 35 complete years (1991-2025). The driest ever recorded: 2007, with 451 mm over the year, against a local average of 843 mm. 2022 ranks as the 3rd driest year out of 35 (510 mm against an average of 843 mm); 2023 follows in 13th place (735 mm).

This ranking gives the true measure of the recent sequence: when the years 2020-2023 crowd into the top of the drought table, the clay has not had time to rehydrate between episodes – the classic scenario for delayed cracks. The reverse is just as instructive: a very wet year following an exceptional drought causes abrupt swelling of the ground.

Forty years of decrees: the complete chronology of Carros

Each line = an event recognised by an interministerial decree published in the Official Gazette (GASPAR database):

• 🔵 11/1982 → 11/1982 – Cyclones / Storms (decree of 15/12/1982)
• 🔵 11/1994 → 11/1994 – Floods (decree of 21/11/1994)
• 🔵 10/1999 → 10/1999 – Floods (decree of 03/03/2000)
• 🔵 10/2000 – Floods (decree of 19/12/2000)
• 🔵 11/2000 – Floods (decree of 29/05/2001)
• 🔵 08/2002 → 08/2002 – Floods (decree of 17/01/2003)
• 🔴 07/2003 → 09/2003 – Drought (clay shrink-swell, RGA) (decree of 27/05/2005)
• 🔵 11/2019 → 11/2019 – Floods (decree of 28/11/2019)
• 🔵 12/2019 – Floods (decree of 28/04/2020)
• 🔵 10/2020 → 10/2020 – Floods (decree of 23/11/2020)
• 🔴 01/2022 → 12/2022 – Drought (clay shrink-swell, RGA) (decree of 03/04/2023)
• 🔴 12/2022 → 09/2023 – Drought (clay shrink-swell, RGA) (decree of 23/09/2024)
• 🔵 03/2024 → 03/2024 – Floods (decree of 29/04/2024)
• 🔵 10/2024 → 10/2024 – Floods (decree of 30/10/2024)

Expert’s reading: 3 droughts and 11 floods. Clusters (several decrees close together) mark the crisis periods – the summer of 2022-2023 is the best recent example. An owner whose damage dates from a covered period has a solid Cat Nat file; outside a covered period, the route is the action against the seller.

Damp, water ingress and rising damp in Carros

Damp in a wall can have four causes – rising damp, water ingress, condensation or a leak – and the treatments are completely different depending on the origin.

We regularly take calls from owners in Carros, often in the sloping neighbourhoods or the old houses of the village, worried about a stain or a musty smell. The reflex is to search the internet and land on an advert promising emergency resin injections or a ventilation system. My message: not so fast. A poorly targeted treatment solves nothing and can cost several thousand euros for nothing.

The four causes and how to recognise them

• Rising damp: stain starting at ground level, rising as a tide mark, often stopping around one metre, render blistering at the foot of walls.
• Water ingress: localised stain near a window, roof or poorly protected outside wall, worsening after rain.
• Condensation: misting on the glazing, mould in corners or the bathroom, linked to lack of ventilation.
• Leak: pinpoint stain near a pipe, a bathroom or a gutter, sometimes with a variation in water flow.

The trap of the diagnosis sold by the treatment contractor

Many companies that sell anti-rising-damp injections are also the ones that carry out the diagnosis. The outcome is predictable: the diagnosis almost always concludes rising damp, even when the real cause is water ingress or condensation. It is a structural conflict of interest, not a question of individual dishonesty.

Before committing to works in Carros, request an independent diagnosis, carried out by an expert who sells no treatment. You can also consult our damp guide for the 06, 83 and 13 to understand reliable diagnostic methods before choosing a treatment.

The official exposure to clay shrink-swell

The GéoRisques platform (BRGM) classifies Carros at high exposure to clay shrink-swell (RGA), with some sectors at medium exposure. This is the benchmark level used by insurers and notaires to assess the risk on a plot.

This ranking complements the decree history above: the hazard tells you what can happen, the decrees tell you what has already happened. A house in a “high exposure” area that has been through one or more dry summers carries a risk of damage that is all the better documented.

Why the weather of 2021-2024 explains your cracks

Annual rainfall recorded on the Carros weather grid (Open-Meteo data):

• 2019: 1,173 mm · 2020: 747 mm · 2021: 694 mm · 2022: 510 mm · 2023: 735 mm · 2024: 1,248 mm
• Average over the period: 851 mm/year, low point in 2022 (510 mm)
• Two dry years in a row: 694 mm in 2021, then 510 mm in 2022
• Clear rebound in 2024: 1,248 mm (+47%)

Clay shrink-swell plays out in two stages, and that is why your cracks appeared long after the drought itself. First the drought dries the clay at depth, the ground shrinks, the first cracks appear. Then the return of the rain rehydrates the ground in one go – swelling and fresh differential movements. If you live in a 1970-2000 villa on shallow foundations, yours is the house that takes the first hit, often 12 to 24 months behind the weather episode: a crack opening today may perfectly well date from the 2022 drought.

Cracks in Carros: the signs that should make you call an expert

• Stair-step crack, through-wall, open by more than 2 mm – measure it with a ruler, that is the threshold from which we start to worry
• A crack that moves over time: fit a tell-tale (a plaster strip or a glass tell-tale) and compare a few months apart
• Other signs to watch together: doors and windows sticking, floor tiles splitting diagonally, render delaminating
• Aggravating factors on your plot: clay soil, tree close to the house, drainage no longer doing its job

With 3 drought decrees to Carros’s name, a combination of several of these signs justifies a survey before any repair – and before any signature, whether you are buyer or seller. Do not have a crack filled before having it dated and surveyed: you would lose the evidence needed for compensation or legal action.

Is my cracked house in Carros compensable? What the law says when buying or selling

Between the recent drought decrees and the volume of transactions, quite a few properties change hands in Carros with damage passed over in silence. If you discover cracks after the purchase, you have two levers:

• Latent defect (Article 1641 of the Civil Code): serious cracks, invisible at the viewing, predating the sale → you can claim a price reduction or cancellation, within 2 years of discovery
• Fraudulent misrepresentation (dol) (Article 1137): the seller knew and concealed the damage → cancellation and damages possible, within 5 years; the commune’s GASPAR decree then supports your file

To engage this action, first have the cracks dated and characterised by an independent expert, then entrust the file to a property lawyer.

What to expect during a drought/clay survey in Carros

• Technical visit at your home: crack mapping and classification, opening measurements, functional damage
• Context: clay zone, the commune’s Cat Nat history (3 drought decrees), local drought episodes
• Repair cost estimates: underpinning, injections, drains – with several scenarios to suit your budget
• Written report, which you can pass directly to your insurer or your lawyer

Independent expert, with no ties to any works company. Request a visit in Carros – also worth reading, our complete RGA and Cat Nat guide for the 06, 83 and 13.

Soil surveys on clay ground: what the regulations say

The requirement for a prior geotechnical study has applied since 1 October 2020 (ELAN Act, art. 68); the new exposure map of 1 July 2026 widens its scope. This obligation, stemming from ELAN Act no. 2018-1021, article 68 (Decree no. 2019-495 of 22 May 2019), applies particularly to Carros (high exposure in the BRGM ranking).

• What it changes for building: the soil survey is no longer an option – the ELAN Act mandates it in exposed zones for any sale of building land and any construction contract. Adapted foundations, ground treatment, drainage arrangements: the specifications flow directly from the survey.
• What it changes when buying a recent property: ask whether the survey was carried out and which specifications were applied. A house built without heeding the geotechnical recommendations on clay ground is a medium-term cracking risk.
• What it changes when selling: the absence of a survey on a property built before the obligation is not a defect in itself – but if damage appears, a seller who knew about it and concealed it exposes themselves to an action for fraudulent misrepresentation.
• The link with the data above: Carros combines high exposure and a documented history of drought decrees. Building or buying here without checking the nature of the ground means building on a known and measured risk.

Cassini Expertise handles these files: compliance checks between geotechnical specifications and execution, surveys of damage on clay ground, second-opinion expert assessments. Request a consultation.

Frequently asked questions

Is Carros among the clay risk zones?

Yes. The Alpes-Maritimes is very largely affected by the clay shrink-swell hazard (BRGM mapping, consultable on georisques.gouv.fr). For Carros, the GASPAR history with its 3 drought decrees confirms that the risk is very real where you live, not merely theoretical on a map.

Can a crack in Carros give rise to Cat Nat compensation?

Only if the damage dates from a period covered by a decree (the last recognised drought periods: 2005, 2023, 2024) and if you declared the claim to your insurer within 30 days. If you have passed that deadline, or if the damage predates your purchase, the action against the seller remains – and in that case, precisely dating the appearance of the cracks through a survey becomes the central element of your file.

Can the figures quoted on this page be checked?

Yes, and we encourage you to do so. The decrees come from the GASPAR database (Official Gazette, open-data datasets, 2025 update), the rainfall from Open-Meteo weather archives for the Carros grid. Cassini Expertise reproduces this data as it stands, without adjusting it.

The drought right now (as at 04/10/2026)

In the commune: recent rain (3 days ago). Rainfall over the last 30 days: 5 mm, against roughly 58 mm expected at this time of year – a 91% deficit.

A sustained deficit over this window, especially in the growing season, often precedes by a few weeks the drops in the water table shown above: it is the first signal owners can track themselves, before the cracks.

This week’s drought watch (as at 05/10/2026)

In the commune: recent rain (4 days ago). Rainfall over the last 30 days: 5 mm, against roughly 59 mm expected at this time of year – a 92% deficit.

A sustained deficit over this window, especially in the growing season, often precedes by a few weeks the drops in the water table shown above: it is the first signal owners can track themselves, before the cracks.

The drought right now (as at 12/10/2026)

In the commune: recent rain (5 days ago). Rainfall over the last 30 days: 19 mm, against roughly 66 mm expected at this time of year – a 71% deficit.

A sustained deficit over this window, especially in the growing season, often precedes by a few weeks the drops in the water table shown above: it is the first signal owners can track themselves, before the cracks.

The drought right now (as at 19/10/2026)

In the commune: no notable rain for 12 days. Rainfall over the last 30 days: 19 mm, against roughly 73 mm expected at this time of year – a 74% deficit.

A sustained deficit over this window, especially in the growing season, often precedes by a few weeks the drops in the water table shown above: it is the first signal owners can track themselves, before the cracks.

Water table memory: 30 years of measurements, a well-documented context

The reference piezometric station for the sector (002FFSZ) has been monitoring the water table since 1997 – 30 years of records. As at 26/09/2026, the mean level over the last thirty days is 70.81 m NGF. Across the whole record, the water table has spent only 24.0% of its time below this level: a low level, in the lower quartile of known values.

• Last comparable episode: 30/10/2023 – 2.9 years ago
• Frequency: 19 similar episodes recorded since 1997, i.e. a return every 2 years on average – in hydrologists’ language, an intermediate episode
• Historical minimum: 65.58 m NGF, reached on 24/10/2022

This long memory changes how the risk is read: a low level is not merely a weather episode, it is an event whose frequency is known. For a house on clay, it is that frequency that informs the probability of further settlement – and hence the urgency of precautions.

Survey carried out by Frédéric Faucouneau, independent building expert – Antibes, Alpes-Maritimes (06), Var (83), Bouches-du-Rhône (13). Find out more

📅 Last updated 24/10/2026 - Cassini Expertise, independent building expert – departments 06, 83 and 13.