Aubagne: Clay Soil, Subsidence and Cracks – Official Data

The geological and climate context of Aubagne

Aubagne combines a well-documented clay exposure and a substantial Cat Nat record: the GASPAR database lists 13 drought decrees (full list below) and 15 flood decrees, i.e. 28 Cat Nat decrees. Same logic on the weather side: two dry years (2020, 2022), then 2024 back up to 730 mm (+21%) – precisely this alternation that puts foundations to work in Pagnol’s town and on the hills of the Garlaban. If your house is in this sector and shows cracks, the first thing to do is check whether their appearance matches one of these periods: that is what will guide your next steps.

Cassini Expertise, an independent building expert, handles drought-related cracks and damage in Aubagne and across the whole of the 13. This page brings together the commune’s official data, with no commercial angle – enough to prepare a file before calling an expert or a lawyer.

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

According to GASPAR (decrees published in the Official Gazette since 1982), Aubagne has recorded a total of 28 natural disaster decrees. Keep this list handy: it is what makes it possible to say whether your cracks can give rise to Cat Nat compensation.

• 13 drought decrees (differential ground movement linked to clay shrink-swell)
  • event of 01/09/1988 (decree of 18/08/1995)
  • event of 01/05/1989 (decree of 14/01/1992)
  • event of 01/01/1991 (decree of 03/03/1995)
  • event of 01/10/1993 (decree of 19/05/1999)
  • event of 01/01/2002 (decree of 25/08/2004)
  • event of 01/01/2005 (decree of 20/02/2008)
  • event of 01/01/2006 (decree of 18/04/2008)
  • event of 01/01/2016 (decree of 25/07/2017)
  • event of 01/04/2017 (decree of 23/10/2018)
  • event of 01/01/2018 (decree of 16/07/2019)
  • event of 01/07/2019 (decree of 29/04/2020)
  • event of 01/04/2022 (decree of 03/04/2023)
  • event of 01/04/2023 (decree of 18/06/2024)
• 15 flood and storm decrees

Each drought decree covers a precise window of time. What to do with it in practice: note the approximate date your cracks appeared and compare it with these periods. If it matches, Cat Nat compensation is conceivable – provided the claim was declared to your insurer within 30 days of the decree. If it does not match, or you bought the house afterwards without being informed, the route of a claim against the seller for hidden defect or fraudulent concealment remains (see below).

What the official clay mapping says

The GéoRisques platform (BRGM) classifies Aubagne at high exposure to clay shrink-swell, with some sectors at medium exposure. This is the benchmark level insurers and notaires consult before a sale – you can check the exact plot on georisques.gouv.fr before buying or doing foundation works. Another point not to overlook: the commune sits in radon potential class 2 (IRSN/GéoRisques data), which justifies a dosimeter if you spend time in a basement or poorly ventilated ground floor.

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 been through one or more dry summers, assume the risk of damage is not theoretical.

What characterises Aubagne from a building surveying perspective

In Aubagne, the same signatures of damage come up regularly on villas built between the 1970s and 90s, which occupy the plain of the Huveaune and the first rises around the Garlaban massif and the Sainte-Baume. The clayey-marly soil typical of this basin is particularly sensitive to moisture swings: during summer drought the clay contracts sharply, then swells again with the autumn rains, generating repeated soil movements under the foundations. Yet a large share of the Aubagne building stock – notably the estate bungalows built quickly during the property booms of the 1980s – rests on shallow, lightly reinforced foundations, undersized to absorb these shrink-swell cycles. We also see that the presence of large pines and oaks, often planted too close to the homes in these residential quarters, makes matters worse: their roots pump the residual moisture from the soil in summer, deepening the desiccation of the clay under part of the house only. This uneven drying produces characteristic differential settlement, with stair-step cracks on façade corners or around openings. The outlying bungalow quarters, built on the clayey piedmonts rather than on the older, better-settled historic centre, are the ones where we are most often called out for this type of pathology.

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: 2007, with 400 mm over the year, against a local average of 666 mm. 2022 ranks as the 5th driest year out of 35 (488 mm against an average of 666 mm); 2023 follows in 9th place (524 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.

Aubagne: 28 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 – Cyclones / Storms (decree of 18/11/1982)
• 🔵 11/1982 → 11/1982 – Floods (decree of 18/11/1982)
• 🔵 08/1986 → 08/1986 – Floods (decree of 11/12/1986)
• 🔴 09/1988 → 04/1989 – Drought (RGA – clay shrink-swell) (decree of 18/08/1995)
• 🔴 05/1989 → 12/1990 – Drought (RGA – clay shrink-swell) (decree of 14/01/1992)
• 🔵 09/1989 → 09/1989 – Floods (decree of 08/01/1990)
• 🔴 01/1991 → 09/1993 – Drought (RGA – clay shrink-swell) (decree of 03/03/1995)
• 🔵 10/1991 → 10/1991 – Floods (decree of 21/09/1992)
• 🔴 10/1993 → 12/1998 – Drought (RGA – clay shrink-swell) (decree of 19/05/1999)
• 🔵 01/1994 → 01/1994 – Floods (decree of 26/01/1994)
• 🔵 08/1996 – Floods (decree of 09/12/1996)
• 🔵 09/1998 – Floods (decree of 29/12/1998)
• 🔵 09/1999 – Floods (decree of 28/01/2000)
• 🔴 01/2002 → 06/2002 – Drought (RGA – clay shrink-swell) (decree of 25/08/2004)
• 🔵 12/2003 → 12/2003 – Floods (decree of 12/12/2003)
• 🔴 01/2005 → 03/2005 – Drought (RGA – clay shrink-swell) (decree of 20/02/2008)
• 🔴 01/2006 → 03/2006 – Drought (RGA – clay shrink-swell) (decree of 18/04/2008)
• 🔵 06/2008 – Floods (decree of 24/12/2008)
• 🔵 12/2008 → 12/2008 – Floods (decree of 17/04/2009)
• 🔴 01/2016 → 09/2016 – Drought (RGA – clay shrink-swell) (decree of 25/07/2017)
• 🔴 04/2017 → 09/2017 – Drought (RGA – clay shrink-swell) (decree of 23/10/2018)
• 🔴 01/2018 → 03/2018 – Drought (RGA – clay shrink-swell) (decree of 16/07/2019)
• 🔵 08/2018 – Floods (decree of 22/10/2018)
• 🔴 07/2019 → 09/2019 – Drought (RGA – clay shrink-swell) (decree of 29/04/2020)
• 🔵 10/2019 → 10/2019 – Floods (decree of 30/10/2019)
• 🔵 10/2021 → 10/2021 – Floods (decree of 15/10/2021)
• 🔴 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)

How an expert reads this: 13 droughts and 15 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 Aubagne

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 have a damp problem in Aubagne, and you may already have read online that resin injections are needed, or a ventilation system. My message: not so fast. Without a diagnosis, you risk paying for an ineffective treatment aimed at a cause that is not the right one.

The four causes and how to recognise them

• Rising damp: stains climbing from the ground over 1 to 1.5 m, often low on the wall, with saltpetre and crumbling render.
• Water ingress: localised halos near a roof, a cracked façade or a gutter, often correlated with rain.
• Condensation: mould in cold corners, on windows, in a poorly ventilated bathroom, with no link to the ground.
• Leak: a pinpoint stain near a pipe run, a bathroom or a kitchen, sometimes with a smell.

The trap of the diagnosis sold by the treatment contractor

In Aubagne as elsewhere, many companies selling resin injections offer a “free quotation” before selling their own treatment. The problem: they are rarely trained to distinguish the four causes, and their commercial interest is to conclude rising damp systematically, even when it is water ingress or condensation. The result: costly works – sometimes several thousand euros – that solve nothing because the real cause has not been treated.

The only way to secure your decision is to go through an independent diagnosis, carried out by an expert who has nothing to sell afterwards. If you are in Aubagne, contact us for an independent diagnosis: I identify the real cause before any recommendation of works. To dig deeper, see also our damp guide for the 06, 83 and 13.

Why do cracks appear several months after the drought?

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

• 2019: 686 mm · 2020: 496 mm · 2021: 695 mm · 2022: 488 mm · 2023: 524 mm · 2024: 730 mm
• Average over the period: 603 mm/year, driest year: 2022 (488 mm)
• Two markedly dry years: 496 mm in 2020, 488 mm in 2022
• Then 2024 bounces back to 730 mm, i.e. +21%

Clay shrink-swell plays out in two stages: the drought dries the clay at depth – hence the shrinkage and the first cracks – then the return of the rains abruptly rehydrates the soil, causing swelling and differential movements. If you own a house on shallow foundations – the case for most villas built between 1970 and 2000 – watch your walls 12 to 24 months after a dry summer: that is the typical delay before cracks appear, not the drought year itself.

Cracks in Aubagne: when to worry and act

• A stair-step crack, passing through the wall, open by more than 2 mm → to be watched closely
• A crack that is evolving: fit a plaster tell-tale over it and check it a few months later
• Associated signs not to be ignored: doors and windows that stick, floor tiles splitting diagonally, render that bulges
• Aggravating factors on your land: clay soil, trees close to the house, failing drainage

With 13 drought decrees on Aubagne’s record, as soon as several of these signals stack up in your home, do not repair at once: first have the damage recorded by an expert. A too-hasty repair can erase the evidence needed for compensation or a claim, whether you are selling or buying.

A cracked house in Aubagne: buying, selling, claiming against the seller

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

• Hidden defect (vice caché, Article 1641 of the French Civil Code): serious cracks, not detectable at a viewing, predating the sale → you can claim a price reduction or cancellation of the sale
• Fraudulent concealment (dol, Article 1137): the seller knew and said nothing → cancellation plus damages, within 5 years; the commune’s GASPAR decree then strengthens your file

In both cases, a survey that precisely dates the appearance of the cracks is what swings the file. On this legal aspect, instruct a French property lawyer.

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

• Technical visit: mapping and classification of each crack, width measurements, functional disorders (doors, windows, floor tiles)
• Context analysis: clay zoning, the commune’s Cat Nat history (13 drought decrees), local drought episodes cross-checked against the date the damage appeared
• Costing of repair works: underpinning, injections, drains – with several scenarios to suit your budget
• A written report directly usable by your insurer or your lawyer to build the file

Independent expert, with no ties to any works company – which means the diagnosis is never steered towards selling works. Request a visit in Aubagne – 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 Aubagne (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: Aubagne 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, counter-surveys. Request a consultation.

Frequently asked questions

Is Aubagne in a clay risk zone?

The Bouches-du-Rhône is very largely covered by the clay shrink-swell hazard (BRGM map, consultable on georisques.gouv.fr). For Aubagne, the 13 drought decrees recorded in GASPAR confirm the risk is real, not theoretical – if you are buying or building here, check the exact classification of your plot before signing.

Can a cracked house in Aubagne be covered under Cat Nat provisions?

Only if the damage can be tied to a period covered by a decree (recognised drought periods: 1992, 1995, 1999, 2004, 2008, 2017, 2018, 2019, 2020, 2023, 2024) and if the claim was declared within 30 days of the decree being published. Failing that, the action against the seller remains – and precisely dating the damage by survey then becomes the central issue of your file.

Can the figures cited on this page be verified?

Yes: the decrees come from the GASPAR database (Official Gazette, open data, 2025 update), the rainfall from the Open-Meteo weather archives for the Aubagne grid. Cassini Expertise reports this data exactly as it stands, without adjusting it – you can cross-check it yourself before making any decision to buy, sell or commission works.

What is the rainfall situation? (as at 04/10/2026)

In the commune: recent rain (3 days ago). Rainfall over the last 30 days: 29 mm, against roughly 55 mm expected at this time of year – a 47% 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.

Weekly drought update (as at 05/10/2026)

In the commune: recent rain (4 days ago). Rainfall over the last 30 days: 29 mm, against roughly 56 mm expected at this time of year – a 48% 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 today? (as at 12/10/2026)

In the commune: recent rain (5 days ago). Rainfall over the last 30 days: 57 mm, against roughly 61 mm expected at this time of year – a 7% 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.

Weekly drought update (as at 19/10/2026)

In the commune: recent rain (1 day ago). Rainfall over the last 30 days: 68 mm, against roughly 66 mm expected at this time of year – a surplus of 3%.

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.

The water table against its historical record: what 29 years of measurements show

The reference piezometric station for the sector (002JNGC) has been monitoring the water table since 1998 – 29 years of records. As at 02/10/2026, the mean level over the last thirty days is 211.61 m NGF. Across the whole record, the water table has spent only 15.1% of its time below this level: a very low level, rarely reached in the station’s record.

• Last comparable episode: 03/10/2024 – 2.0 years ago
• Frequency: 64 similar episodes recorded since 1998, i.e. a return every year on average – in hydrologists’ language, a rare event
• Historical minimum: 210.96 m NGF, reached on 05/08/2017

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.