Arles: Clay Soil, Subsidence and Cracks – Official Data

The geological and climate context of Arles

Yes, probably, if your house sits on shallow foundations: Arles has 5 drought decrees (full list below) and 18 flood decrees, i.e. 23 Cat Nat decrees, and the commune is classed at high exposure to clay shrink-swell. The rainfall record confirms the mechanism: two deficit years (491 mm in 2020, 420 mm in 2023), then a rebound to 887 mm in 2024 – precisely the drought-then-rain scenario that puts foundations to work in this commune wedged between the Rhône and the Crau.

Cassini Expertise, an independent building expert, handles drought-related cracks and damage in Arles and across the whole of the 13. This page brings together the official data available for the commune, with no commercial angle, to help you work out whether your case is documented and what to do next.

Arles: drought, clay and cracks – what the official data says

According to GASPAR (decrees published in the Official Gazette since 1982), the commune of Arles has recorded a total of 23 natural disaster decrees:

• 5 drought decrees (differential ground movement linked to clay shrink-swell)
  • event of 01/01/2002 (decree of 18/04/2008)
  • event of 01/01/2018 (decree of 19/11/2019)
  • event of 01/04/2022 (decree of 03/04/2023)
  • event of 01/04/2023 (decree of 18/06/2024)
  • event of 01/10/2023 (decree of 18/06/2024)
• 18 flood and storm decrees

What to do with it: note the date your cracks appeared and compare it with the periods above. If it falls within a recognised window, the Cat Nat route is open – provided you declared the claim to your insurer within 30 days of the decree. If the date does not match, or the declaration was not made in time, the claim against the seller for hidden defect or fraudulent concealment remains (see below). In both cases, keep every dated photograph of your cracks: it is the most useful piece of evidence for dating the loss.

What the official clay mapping says

The GéoRisques platform (BRGM) classifies Arles at high exposure to clay shrink-swell, with some sectors at medium exposure. This is the benchmark level insurers and notaires consult to assess the risk on a plot – you can check yours free of charge on georisques.gouv.fr before buying or commissioning works.

This ranking complements the decree history: 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 – an argument that carries weight both in a survey and in a price negotiation when buying.

Why every file in Arles is read through its local context

In Arles, the question of cracks arises in a particular geological setting: the commune stretches between the alluvial plain of the Rhône, its silty terraces and a few drier hillocks such as the Trébon area or towards Pont-de-Crau, where clay soils alternate with old fill linked to the river’s historical wanderings. We are regularly called to renovated Provençal farmhouses, 1970s-80s villas built on the edges of the historic centre, and more recent houses from the estates that multiplied towards Raphèle or Moulès. These buildings mostly rest on shallow foundations, poorly suited to a clay soil that reacts strongly to moisture swings: in dry periods the clay shrinks and loses volume, causing differential settlement that shows up as façade cracks, often stair-step ones near openings. Plane trees, pines and cypresses planted right next to homes make things worse, their roots pumping water from the soil and deepening the clay shrinkage locally. Houses with no crawl space, set directly on shallow strip footings, are the most exposed – as are extensions built on ground different from the original structure, which create points of mechanical rupture. It is this combination of Rhône-inherited clay soil, unreinforced older buildings and tree cover close to the foundations that explains how often crack defects are observed on the ground in Arles.

Drought in the rear-view mirror: 35 years of measured rainfall

The weather archives for the area cover 35 complete years (1991-2025). The driest ever recorded: 2017, with 405 mm over the year, against a local average of 617 mm. 2022 ranks as the 15th driest year out of 35 (561 mm against an average of 617 mm); 2023 follows in 4th place (420 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.

Arles: 23 Cat Nat decrees since 1982, in chronological order

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

• 🔵 11/1982 → 11/1982 – Floods (decree of 18/11/1982)
• 🔵 11/1982 → 11/1982 – Cyclones / Storms (decree of 18/11/1982)
• 🔵 10/1988 → 10/1988 – Floods (decree of 20/04/1989)
• 🔵 09/1990 → 09/1990 – Floods (decree of 25/01/1991)
• 🔵 10/1993 → 10/1993 – Floods (decree of 29/11/1993)
• 🔵 01/1994 → 01/1994 – Floods (decree of 26/01/1994)
• 🔵 11/1994 → 11/1994 – Floods (decree of 21/11/1994)
• 🔵 09/1995 → 09/1995 – Floods (decree of 08/01/1996)
• 🔵 09/1998 → 09/1998 – Floods (decree of 23/02/1999)
• 🔵 08/1999 – Floods (decree of 02/05/2000)
• 🔵 10/1999 → 10/1999 – Floods (decree of 03/03/2000)
• 🔴 01/2002 → 06/2002 – Drought (RGA – clay shrink-swell) (decree of 18/04/2008)
• 🔵 09/2002 → 09/2002 – Floods (decree of 19/09/2002)
• 🔵 11/2002 → 11/2002 – Floods (decree of 24/02/2003)
• 🔵 09/2003 – Floods (decree of 03/12/2003)
• 🔵 12/2003 → 12/2003 – Floods (decree of 12/12/2003)
• 🔵 09/2010 → 09/2010 – Floods (decree of 02/12/2010)
• 🔵 11/2011 → 11/2011 – Floods (decree of 18/11/2011)
• 🔴 01/2018 → 03/2018 – Drought (RGA – clay shrink-swell) (decree of 19/11/2019)
• 🔵 10/2019 – Floods (decree of 18/11/2019)
• 🔴 04/2022 → 09/2022 – Drought (RGA – clay shrink-swell) (decree of 03/04/2023)
• 🔴 04/2023 → 06/2023 – Drought (RGA – clay shrink-swell) (decree of 18/06/2024)
• 🔴 10/2023 → 12/2023 – Drought (RGA – clay shrink-swell) (decree of 18/06/2024)

How an expert reads this: 5 droughts and 18 floods. Clusters (several decrees close together) mark crisis periods – the summer sequence 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 a claim against the seller.

Damp, water ingress and rising damp in Arles

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.

You live in Arles and damp marks are appearing on your walls? Before jumping on a solution found online – injections or a ventilation system – you first need to understand where the problem comes from. The Arles building stock, often old and built of stone or traditional masonry, is particularly sensitive to these disorders, especially near the Rhône.

The four causes and how to recognise them

• Rising damp: groundwater climbs into the walls by capillary action. A stain rising from the base, often with saltpetre and render that crumbles, usually capped around one metre.
• Water ingress: water penetrates from outside (roof, cracked façade, failing gutter). The stain appears higher up or follows a precise path, and worsens after rain.
• Condensation: linked to poor ventilation and temperature differences. It mainly affects cold corners, bathrooms and kitchens, with surface mould.
• Leak: defective pipe or drain. The stain is localised, often near a kitchen, bathroom or service duct, and can worsen steadily.

The trap of the diagnosis sold by the treatment contractor

Many damp-treatment companies offer a “free quotation” which, by an amazing coincidence, always concludes that rising damp is present and requires their resin injections. The problem: that diagnosis is made by whoever then sells the solution, with no independence whatsoever. A frequent outcome in Arles: owners pay for costly injections when the real problem was a blocked gutter or a missing ventilation system – and the damp returns a few months later.

An independent damp diagnosis identifies the true cause before any works, and saves you paying twice. If you are in Arles, we can carry out this diagnosis with no ties to any treatment company: contact us here. To go further on diagnostic and treatment methods, see our damp guide for the 06, 83 and 13.

Why do cracks appear several months after the drought?

Annual rainfall measured on the Arles weather grid (Open-Meteo data):

• 2019: 629 mm · 2020: 491 mm · 2021: 741 mm · 2022: 561 mm · 2023: 420 mm · 2024: 887 mm
• Average over the period: 621 mm/year, driest year: 2023 (420 mm)
• Two markedly dry years: 491 mm in 2020, 420 mm in 2023
• Then a clear rebound in 2024, at 887 mm (+43%)

Clay shrink-swell plays out in two stages: the drought dries the clay at depth, causing shrinkage and the first cracks, then the return of the rains abruptly rehydrates the ground and generates a swelling that deepens the differential movements. If your house was built between 1970 and 2000 on shallow foundations – the case for most villas in the region – it absorbs the first damage, often with a lag of 12 to 24 months after the dry episode. In practical terms: cracks that appeared in 2024 or 2025 may well trace back to the drought of 2022-2023.

Are my cracks serious? The signs that should push you to act

• A stair-step crack, passing through the wall, open by more than 2 mm
• A crack that is evolving (fit a plaster tell-tale or a dated marker and monitor it over several months)
• Associated signs: doors and windows that stick, floor tiles splitting diagonally, render that bulges
• A house built on clay, a tree close by, failing drainage

With 5 drought decrees already recognised for the commune, the presence of several of these indicators warrants a survey before any repair – filling an active crack without a diagnosis only masks the problem – and before any signature, whether buying or selling.

Buying or selling a cracked house in Arles: what recourse do you have?

With the recent drought decrees and the volume of transactions under way, a fair number of properties change hands with damage passed over in silence. If you discover cracks after buying, two levers exist:

• Hidden defect (vice caché, Article 1641 of the French Civil Code): serious cracks, not detectable at a viewing, predating the sale → price reduction or cancellation of the sale
• Fraudulent concealment (dol, Article 1137): the seller knew about the claim and hid it → cancellation of the sale plus damages, within 5 years

In both cases, a survey serves to date the damage and establish whether it was visible or concealed at the time of the sale – that is often what tips the file one way or the other. On the legal side, instruct a French property lawyer.

What actually happens during a drought/clay survey in Arles?

• On-site visit: mapping and classification of your cracks, width measurements, functional disorders recorded
• Context analysis: clay zoning, the commune’s Cat Nat history (5 drought decrees), local drought episodes
• Works estimate: underpinning, injections, drainage – several costed scenarios, so you can compare contractors’ quotations
• A written report passed to your insurer or your lawyer to support your file

Independent expert, with no ties to any works company – the opinion given steers you towards no particular contractor. Request a visit in Arles – see also our complete guide to RGA and Cat Nat in the 06, 83 and 13.

Soil surveys on clay ground: what the regulations say

The requirement for a prior geotechnical survey has applied since 1 October 2020 (ELAN law, art. 68); the new exposure map of 1 July 2026 widens its scope. This requirement, introduced by the ELAN law no. 2018-1021, article 68 (decree no. 2019-495 of 22 May 2019), applies to Arles (high exposure under the BRGM classification).

• What it changes for building: a soil survey is no longer optional – the ELAN law makes it compulsory in exposed zones for any sale of unbuilt 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 following the geotechnical recommendations on clay ground is a medium-term cracking risk.
• What it changes for sellers: the absence of a survey on a property built before the requirement is not a defect in itself – but if damage appears, a seller who knew about it and concealed it exposes themselves to a claim for fraudulent concealment (dol).
• The link with the data above: Arles combines high exposure with a documented record 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 what was actually built, damage surveys on clay ground, second-opinion expert assessments. Request a consultation.

Frequently asked questions

Is Arles in a clay risk zone?

The Bouches-du-Rhône is very largely covered by the clay shrink-swell hazard (BRGM mapping, consultable on georisques.gouv.fr). For Arles, the GASPAR history with its 5 recognised drought decrees leaves no doubt: the exposure is real, not theoretical. If you are buying or own a property here, assume the risk applies to you.

Is my cracked house in Arles eligible for natural disaster compensation?

Only if your damage falls within a period covered by a decree (the last recognised: 2008, 2019, 2023, 2024) and you declared the claim to your insurer within 30 days of the decree being published. Failing that, the action against the seller remains – and the precise dating of the damage by survey then becomes decisive for your file.

Can the figures on this page be verified?

Yes: the decrees come from the GASPAR database (Official Gazette, open data sets, 2025 update), the rainfall from the Open-Meteo weather archives for the Arles grid. Cassini Expertise merely reports them, without adjusting them – you can cross-check them before making a decision.

Drought right now (as at 04/10/2026)

In the commune: recent rain (3 days ago). Rainfall over the last 30 days: 44 mm, against roughly 57 mm expected at this time of year – a 23% deficit.

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

What is the rainfall situation? (as at 05/10/2026)

In the commune: recent rain (4 days ago). Rainfall over the last 30 days: 44 mm, against roughly 58 mm expected at this time of year – a 24% deficit.

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

Drought right now (as at 12/10/2026)

In the commune: recent rain (5 days ago). Rainfall over the last 30 days: 57 mm, against roughly 63 mm expected at this time of year – a 10% deficit.

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

Drought right now (as at 19/10/2026)

In the commune: no notable rain for 12 days. Rainfall over the last 30 days: 58 mm, against roughly 69 mm expected at this time of year – a 16% deficit.

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

How long since the water table was last this low?

The reference piezometric station for the sector (002JHMX) has been monitoring the water table since 2012 – 15 years of records. As at 21/09/2026, the mean level over the last thirty days is 1.65 m NGF. Across the whole record, the water table has spent only 75.0% of its time below this level: a sustained level for the season.

• Last comparable episode: 03/10/2024 – 2.0 years ago
• Frequency: 69 similar episodes recorded since 2012, i.e. a return every year on average – in hydrologists’ language, an intermediate episode
• Historical minimum: 1.17 m NGF, reached on 07/04/2021

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.

Find out more: Article 1641 of the Civil Code and the hidden defects warranty (garantie des vices cachés), explained.

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

📅 Last updated 06/11/2026 - Cassini Expertise, independent building expert – departments 06, 83 and 13.