Cagnes-sur-Mer: Clay Soil, Subsidence and Cracks – Official Data

Forty years of decrees: the complete timeline of Cagnes-sur-Mer

Each line = an event recognised by a prefectoral decree published in the Journal officiel (GASPAR database):

• 🔵 11/1982 → 11/1982 – Cyclones / Storms (decree of 15/12/1982)
• 🔵 11/1982 → 11/1982 – Floods (decree of 04/02/1983)
• 🔵 08/1983 – Hail / snow (decree of 10/09/1983)
• 🔵 08/1983 – Cyclones / Storms (decree of 10/09/1983)
• 🔵 08/1983 – Floods (decree of 10/09/1983)
• 🔵 10/1987 → 10/1987 – Floods (decree of 02/12/1987)
• 🔵 10/1990 → 10/1990 – Floods (decree of 25/01/1991)
• 🔵 10/1992 – Floods (decree of 04/02/1993)
• 🔵 10/1993 → 10/1993 – Floods (decree of 19/10/1993)
• 🔵 01/1994 → 01/1994 – Floods (decree of 12/04/1994)
• 🔵 11/1994 → 11/1994 – Floods (decree of 21/11/1994)
• 🔵 01/1996 → 01/1996 – Floods (decree of 02/02/1996)
• 🔵 10/1998 – Floods (decree of 21/01/1999)
• 🔵 10/1999 → 10/1999 – Floods (decree of 03/03/2000)
• 🔵 10/2000 – Floods (decree of 19/12/2000)
• 🔵 11/2000 → 11/2000 – Floods (decree of 19/12/2000)
• 🔵 11/2000 → 11/2000 – Floods (decree of 29/05/2001)
• 🔴 07/2003 → 09/2003 – Drought (RGA – clay shrink-swell) (decree of 27/05/2005)
• 🔵 09/2005 → 09/2005 – Floods (decree of 10/10/2005)
• 🔵 12/2005 → 12/2005 – Floods (decree of 05/05/2006)
• 🔴 07/2007 → 09/2007 – Drought (RGA – clay shrink-swell) (decree of 07/08/2008)
• 🔵 10/2010 → 11/2010 – Floods (decree of 30/03/2011)
• 🔵 11/2011 → 11/2011 – Floods (decree of 21/12/2011)
• 🔵 09/2012 – Floods (decree of 10/01/2013)
• 🔵 11/2014 → 11/2014 – Floods (decree of 29/12/2014)
• 🔵 11/2014 → 11/2014 – Floods (decree of 17/02/2015)
• 🔵 09/2015 – Floods (decree of 28/10/2015)
• 🔵 10/2015 – Floods (decree of 07/10/2015)
• 🔴 01/2016 → 12/2016 – Drought (RGA – clay shrink-swell) (decree of 25/07/2017)
• 🔵 11/2019 – Floods (decree of 28/04/2020)
• 🔵 11/2019 → 11/2019 – Floods (decree of 28/11/2019)
• 🔵 12/2019 → 12/2019 – Floods (decree of 28/04/2020)
• 🔵 10/2020 → 10/2020 – Floods (decree of 07/10/2020)
• 🔴 04/2022 → 09/2022 – Drought (RGA – clay shrink-swell) (decree of 03/04/2023)
• 🔴 03/2023 → 06/2023 – Drought (RGA – clay shrink-swell) (decree of 23/09/2024)

How an expert reads this: 5 droughts and 30 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.

The official clay zoning (GéoRisques/BRGM)

The GéoRisques platform (BRGM) classifies Cagnes-sur-Mer as high exposure to clay shrink-swell (RGA – retrait-gonflement des argiles), with some sectors at medium exposure. This is the reference level used by insurers and notaires to assess the risk on a plot.

This zoning completes the decree record above: the hazard level 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.

The official clay shrink-swell exposure rating

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

This zoning completes the decree record above: the hazard level 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.

What 35 years of local rainfall tell us

Weather archives for the area cover 35 complete years (1991-2025). The driest ever recorded: 2007, with 451 mm of rain over the year, against a local average of 828 mm. 2022 ranks as the 3rd driest year out of 35 (534 mm vs an 828 mm average); 2023 follows in 7th place (611 mm).

This ranking gives the true measure of the recent sequence: when the years 2020-2023 all sit near the top of the dry-years table, the clay has had no time to rehydrate between episodes – the textbook scenario for delayed cracking. The reverse is just as telling: a very wet year following an exceptional drought triggers abrupt swelling of the ground.

Damp, water ingress and rising damp in Cagnes-sur-Mer

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 Cagnes-sur-Mer. You may already have read online that you need resin injections or a mechanical ventilation system. Our message: not so fast. Without knowing where the water really comes from, you risk spending several thousand euros on a useless treatment.

The 4 causes and how to recognise them

• Rising damp: ground water climbs into the walls by capillary action. Marks at the base of walls, up to 1 m high, often on older houses in Cagnes with no damp-proof course.
• Water ingress: water enters from outside (roof, façade, joinery). Localised marks, often rain-related, that can appear high up.
• Condensation: moisture in the air settles on cold surfaces. Mould in corners, bathrooms, poorly ventilated rooms, with no link to the ground.
• Leak: a defective pipe or drain. A stain that spreads gradually, often near a bathroom or kitchen, independent of the weather.

The trap of the diagnosis sold by the treatment contractor

In Cagnes-sur-Mer as elsewhere, many injection companies offer a “free quote” before selling their treatment. The problem: they have an interest in concluding it is rising damp, because that is what they know how to treat. As a result, owners pay for injections when the real problem was a blocked gutter or a missing ventilation system.

An independent diagnosis, carried out by an expert with no ties to a treatment company, identifies the true cause before any works are committed. If you are in Cagnes-sur-Mer and notice damp, request an independent survey before accepting any treatment quote. To go further, read our damp guide for the 06, 83 and 13.

Cagnes-sur-Mer: drought, clay and cracks – what the official figures say

Can your cracked house in Cagnes-sur-Mer be linked to drought? The commune’s clay soil is well documented and its Cat Nat record substantial: the GASPAR database lists 5 drought decrees (full list below) and 30 flood decrees, i.e. 35 natural disaster (Cat Nat) decrees. Local rainfall fits the picture: three dry years in a row (2021, 2022, 2023), then 2024 climbs back to 1,196 mm (+50%) – the very alternation that puts foundations to work in Le Racé and Cros-de-Cagnes.

Cassini Expertise, an independent building expert, handles cracks and drought-related damage in Cagnes-sur-Mer and throughout the 06. This page brings together the commune’s official data, point by point, to help you work out whether your case is affected and what to do – with no commercial angle.

Has my house already been covered by a drought natural disaster decree in Cagnes-sur-Mer?

The GASPAR database (decrees published in the Journal officiel since 1982) counts 35 natural disaster decrees for the commune. Compare the dates below with when your cracks appeared: if they coincide, keep this page carefully – it will serve as a supporting document for your file.

• 5 drought decrees (differential ground movement linked to clay shrink-swell)
  • event of 01/07/2003 (decree of 27/05/2005)
  • event of 01/07/2007 (decree of 07/08/2008)
  • event of 01/01/2016 (decree of 25/07/2017)
  • event of 01/04/2022 (decree of 03/04/2023)
  • event of 31/03/2023 (decree of 23/09/2024)
• 30 flood decrees and storm

Each drought decree covers a precise period: if your house’s damage dates from one of these recognised periods, Cat Nat compensation is on the cards – provided the declaration was made within 30 days. If that deadline has passed, or your cracks are more recent, what remains is the claim against the seller for hidden defect (vice caché) or fraudulent concealment (dol) (see below).

Is my plot in a clay risk zone?

The GéoRisques platform (BRGM) classifies Cagnes-sur-Mer as high exposure to clay shrink-swell, with some sectors at medium exposure. This is the reference level used by insurers and notaires to assess the risk on a plot: before buying, ask for the risk statement (ERNMT – état des risques), which must mention this zoning.

This zoning completes the decree record above: the hazard level 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 – the typical profile of the files we survey.

Why do my cracks appear after the rain, not during the drought?

Annual rainfall recorded on the Cagnes-sur-Mer weather grid (Open-Meteo data):

• 2019: 1,142 mm · 2020: 692 mm · 2021: 624 mm · 2022: 534 mm · 2023: 611 mm · 2024: 1,196 mm
• Average over the period: 799 mm/year, driest year: 2022 (534 mm)
• Three deficit years (2021, 2022, 2023): 624 mm, then 534 mm, then 611 mm
• And 2024 bouncing back to 1,196 mm (+50%)

Clay shrink-swell plays out in two phases: the drought dries the clay at depth (shrinkage, first cracks), then the return of the rain rehydrates the ground in one go (swelling, differential movement). If you live in a villa built between 1970 and 2000 on shallow foundations, yours is the house that takes the hit first – with a 12 to 24-month lag after the dry episode. Remember this window: it lets you link a recent crack to a past drought, which is useful for a Cat Nat declaration.

Are my cracks linked to drought or to something else?

Check these signs before any repair:

• A stair-step crack, passing through the wall, more than 2 mm wide
• A crack that evolves (fit a plaster or paper tell-tale over it, and check it again several months apart)
• Associated disorders: doors and windows that stick, floor tiles splitting diagonally, render that bulges
• A house on clay ground, a tree close by, defective drainage

With 5 drought decrees on Cagnes-sur-Mer’s record, a combination of several of these signs justifies a survey before any repair – and before any buying or selling decision. Do not fill in a crack without photographing and measuring it first: it is the only evidence that carries weight with an insurer.

How can I tell whether the ground really has moved under my house?

The piezometric station for the area (ADES/Hubeau network, regular measurements) tells the story of the drought better than any words. Average summer water table level, in metres NGF (the French ordnance datum):

• summer 2021: 71.86 m
• summer 2022: 69.74 m
• summer 2023: 70.35 m
• summer 2024: 71.93 m
• summer 2025: 72.16 m

The trend speaks for itself: the water table fell by almost 2.12 m between summer 2021 and summer 2022, then rose back above its starting level (72.16 m in the last known summer). This back-and-forth sums up clay shrink-swell: the clay ground shrinks when the water table drops, then swells again when it rises. Your foundations do not follow these movements at the same pace – hence cracks appearing 12 to 24 months after dry summers. If a crack appeared in 2023 or 2024, it is the 2022 drop you should be looking at.

Buying or selling a cracked house in Cagnes-sur-Mer: what are your options?

Between the recent drought decrees and the number of transactions under way, many properties change hands with damage passed over in silence. If you discover cracks after buying, you have two levers:

• Hidden defect (vice caché, Article 1641 of the French Civil Code): serious cracks, not visible at the viewing, that predate the sale → price reduction or cancellation, within 2 years of discovery
• Fraudulent concealment (dol, Article 1137): the seller knew and concealed the damage → cancellation and damages, within 5 years; the commune’s GASPAR decree record then supports the file

Before starting proceedings, have the cracks dated and characterised by an independent expert – it is this piece that will allow your French property lawyer to choose between the two routes.

What actually happens during a drought/clay survey?

• Technical visit: crack mapping and classification, width measurements, functional disorders
• Context: clay zoning, the commune’s Cat Nat history (5 drought decrees), local drought periods
• Costing of works: underpinning, injections, drains – with several scenarios
• A written report usable by the insurer or the lawyer

For an on-site survey: building expert in Cagnes-sur-Mer.

Independent expert, with no ties to any repair company. Request a visit in Cagnes-sur-Mer – see also 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 preliminary 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 particularly to Cagnes-sur-Mer (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: Cagnes-sur-Mer 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 Cagnes-sur-Mer among the clay risk zones?

The Alpes-Maritimes is largely affected by the clay shrink-swell hazard (BRGM mapping, consultable on georisques.gouv.fr). In Cagnes-sur-Mer, the 5 drought decrees recorded in GASPAR show that this risk is anything but theoretical.

Can a cracked house in Cagnes-sur-Mer be compensated under natural disaster provisions?

Only if the damage falls within a period covered by a decree (the last recognised periods: 2005, 2008, 2017, 2023, 2024) and if the declaration was filed within 30 days. Failing that, the action against the seller remains – and there, it is the expert dating of the damage that tips the file one way or the other.

Can the figures on this page be checked independently?

Yes: the decrees come from the GASPAR database (Journal officiel, open data sets, updated 2025), and the rainfall figures from the Open-Meteo weather archives for the Cagnes-sur-Mer grid. Cassini Expertise reproduces this data as it stands, without altering it.

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

In the commune: not a drop of rain for over a month. Rainfall over the last 30 days: 1 mm, against roughly 57 mm expected at this time of year – a 98% deficit.

A sustained deficit over this window, especially during 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 05/10/2026)

In the commune: not a drop of rain for over a month. Rainfall over the last 30 days: 1 mm, against roughly 59 mm expected at this time of year – a 98% deficit.

A sustained deficit over this window, especially during 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: 29 mm, against roughly 69 mm expected at this time of year – a 58% deficit.

A sustained deficit over this window, especially during 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 significant rain for 12 days. Rainfall over the last 30 days: 29 mm, against roughly 80 mm expected at this time of year – a 64% deficit.

A sustained deficit over this window, especially during 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.

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

The reference piezometric station for the area (002FFSZ) has been monitoring the water table since 1997 – 30 years of records. As at 26/09/2026, the average level over the last thirty days is 70.81 m NGF. Across the entire 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 period of once every 2 years on average – in hydrologists’ terms, an intermediate episode
• Historical minimum: 65.58 m NGF, reached on 24/10/2022

This long memory changes how the risk should be read: a low level is not just a passing weather episode, it is an event whose frequency is known. For a house on clay, it is this frequency that tells you the probability of further settlement – and therefore how urgent the precautions are.

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.