Fréjus: Clay Soil, Subsidence and Cracks – Official Data

Why every file in Fréjus has to be read through its local context

In Fréjus, we regularly work on houses stretching from the Esterel massif to the alluvial plain of the Argens, by way of the Caïs, Villeneuve and Capitou hills, and this diversity of relief alone explains the frequency of the damage we record. The built fabric is highly heterogeneous: Provençal villas from the 60s-70s built with no prior soil survey, housing estates that sprang up in the 80s-90s at the height of the tourist boom, and more recent constructions on sloping ground backfilled in haste. Many of these houses rest on shallow foundations – plain strip footings cast at shallow depth – which do not go below the zone of influence of the roots of the umbrella pines and evergreen oaks so prevalent in Fréjus gardens. Yet these trees, during prolonged summer drought – frequent in this due-south-facing area – pump water from the clay soil at depth and intensify its shrinkage, triggering differential settlement under building corners or extensions poorly tied into the original structure. We also observe that plots close to the hills, where the clay alternates with pockets of more compressible marl, are particularly sensitive to this movement, all the more so as many recent renovations or raised storeys have loaded down structures originally designed to the bare minimum.

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

The area’s weather archives cover 35 complete years (1991-2025). The driest ever recorded: 2007, with 398 mm over the year, against a local average of 828 mm. 2022 ranks as the 4th driest year out of 35 (580 mm against an average of 828 mm); 2023 follows in 10th place (649 mm).

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

Damp, water ingress and rising damp in Fréjus

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 noticed damp marks in Fréjus and are wondering what to do. You may already have read that resin injections are needed, or a mechanical ventilation system. Our advice: not so fast. Without knowing where the water comes from, these treatments can be pointless, or even make the problem worse.

The 4 causes and how to recognise them

• Rising damp: stains climbing from the base of the walls, often up to 1 metre, with efflorescent salts and blistering render. Common in the older houses of Fréjus with no damp-proof course.
• Water ingress: a localised mark, often on a façade or under a roof, that worsens after rain. Linked to a crack, a gutter or failed waterproofing.
• Condensation: misted windows, mould in cold corners, poorly ventilated rooms (bathroom, kitchen). An indoor-air problem, not a structural one.
• Leak: a pinpoint stain near a pipe, an upstairs bathroom or a sink. Can be intermittent and therefore hard to spot.

The trap of the diagnosis sold by the treatment contractor

Many companies selling damp treatments carry out the diagnosis themselves before invoicing you for their solution. The problem: they have an interest in concluding that a paid-for treatment is necessary, even where simply improving ventilation would be enough. In Fréjus we have seen houses where costly injections had been installed when the real problem was a blocked gutter.

Before commissioning any works, have an independent diagnosis carried out in Fréjus, with no commercial ties to a treatment contractor, to identify the true origin of the damp and avoid pointless spending. Contact us for an objective survey, or read the damp guide for 06, 83 and 13 to understand the diagnostic and treatment methods suited to each cause.

Fréjus: drought, clay and cracks – what the decrees say

Fréjus combines a very real clay exposure and a substantial Cat Nat track record: the GASPAR database records 5 drought natural disaster decrees (2003, 2021, 2023, 2024) and 22 flood decrees, i.e. 27 natural disaster declarations (Cat Nat). The rainfall figures confirm the scenario: four deficit years in a row (2020 to 2023), then an abrupt rebound in 2024 at 1,142 mm (+43%) – exactly the kind of alternation that cracks foundations, from the episcopal city down to the Argens plain.

Cassini Expertise, an independent building expert, diagnoses cracks and drought-related damage in Fréjus and throughout the Var. If you have a crack or a purchase project in this area, this page first gives you the official benchmarks to judge how serious it is, with no sales pitch.

Natural disaster declarations (Cat Nat) in Fréjus: the official record

According to the GASPAR database (decrees published in the Journal officiel since 1982), Fréjus totals 27 natural disaster declarations:

• 5 drought prefectoral decrees (differential ground movement linked to clay shrink-swell (RGA))
  • event of 01/02/1998 (prefectoral decree of 08/07/2003)
  • event of 01/01/2002 (prefectoral decree of 08/07/2003)
  • event of 01/04/2020 (prefectoral decree of 21/12/2021)
  • event of 01/04/2022 (prefectoral decree of 03/04/2023)
  • event of 01/04/2023 (prefectoral decree of 18/06/2024)
• 22 flood prefectoral decrees and storm

What to take from this in practical terms: if your cracks appeared during one of these periods (for example in spring 2020, 2022 or 2023), you have a basis for a natural disaster declaration (Cat Nat) claim with your insurer. If the date does not match a decree, or if the 30-day declaration deadline has passed, the remaining route is a claim against the seller for hidden defect (vice caché) or fraud (dol) – in that case keep every dated document (photos, quotes, letters) that pins down when the damage appeared.

What the official clay mapping says

The GéoRisques platform (BRGM) classifies Fréjus at high exposure to clay shrink-swell (RGA), with some sectors at medium exposure. This is the level your insurer and the notaire already look at when assessing a plot – you can check it yourself by entering your address on georisques.gouv.fr before any purchase. Another point not to neglect: the commune is classified at radon potential class 3 (IRSN/GéoRisques data), which justifies a measurement in the living rooms if you live in, or are buying in, the affected zone.

This classification completes the decree history above: the hazard rating says what can happen, the decrees say what has already happened. If your house is in a high-exposure area and has already come through one or more dry summers, take cracks seriously as soon as they go beyond simple surface micro-cracking.

Fréjus: 27 Cat Nat prefectoral decrees since 1982, in chronological order

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

• 🔴 02/1998 → 06/1999 – Drought – clay shrink-swell (RGA) (prefectoral decree of 08/07/2003)
• 🔴 01/2002 → 06/2002 – Drought – clay shrink-swell (RGA) (prefectoral decree of 08/07/2003)
• 🔴 04/2020 → 06/2020 – Drought – clay shrink-swell (RGA) (prefectoral decree of 21/12/2021)
• 🔴 04/2022 → 12/2022 – Drought – clay shrink-swell (RGA) (prefectoral decree of 03/04/2023)
• 🔴 04/2023 → 09/2023 – Drought – clay shrink-swell (RGA) (prefectoral decree of 18/06/2024)

Expert reading: 5 droughts and 22 floods. Clusters (several decrees close together) flag up 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 way forward is an action against the seller.

The complete chronology of the 27 natural disasters recognised in Fréjus

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

• 🔵 08/1983 → 08/1983 – Floods (prefectoral decree of 15/11/1983)
• 🔵 10/1987 → 10/1987 – Floods (prefectoral decree of 25/01/1988)
• 🔵 10/1990 – Floods (prefectoral decree of 25/01/1991)
• 🔵 09/1992 → 09/1992 – Floods (prefectoral decree of 23/06/1993)
• 🔵 10/1993 → 10/1993 – Floods (prefectoral decree of 14/12/1993)
• 🔵 01/1994 → 01/1994 – Floods (prefectoral decree of 27/05/1994)
• 🔵 06/1994 → 06/1994 – Floods (prefectoral decree of 08/09/1994)
• 🔵 01/1996 → 01/1996 – Floods (prefectoral decree of 02/02/1996)
• 🔴 02/1998 → 06/1999 – Drought – clay shrink-swell (RGA) (prefectoral decree of 08/07/2003)
• 🔴 01/2002 → 06/2002 – Drought – clay shrink-swell (RGA) (prefectoral decree of 08/07/2003)
• 🔵 08/2005 → 08/2005 – Floods (prefectoral decree of 02/03/2006)
• 🔵 12/2006 → 12/2006 – Floods (prefectoral decree of 23/03/2007)
• 🔵 09/2009 → 09/2009 – Floods (prefectoral decree of 16/10/2009)
• 🔵 06/2010 → 06/2010 – Floods (prefectoral decree of 21/06/2010)
• 🔵 11/2011 → 11/2011 – Floods (prefectoral decree of 18/11/2011)
• 🔵 01/2014 → 01/2014 – Floods (prefectoral decree of 31/01/2014)
• 🔵 11/2014 → 11/2014 – Floods (prefectoral decree of 03/12/2014)
• 🔵 10/2015 – Floods (prefectoral decree of 07/10/2015)
• 🔵 10/2018 – Floods (prefectoral decree of 28/04/2020)
• 🔵 11/2019 → 11/2019 – Floods (prefectoral decree of 28/11/2019)
• 🔵 12/2019 → 12/2019 – Floods (prefectoral decree of 12/12/2019)
• 🔴 04/2020 → 06/2020 – Drought – clay shrink-swell (RGA) (prefectoral decree of 21/12/2021)
• 🔴 04/2022 → 12/2022 – Drought – clay shrink-swell (RGA) (prefectoral decree of 03/04/2023)
• 🔴 04/2023 → 09/2023 – Drought – clay shrink-swell (RGA) (prefectoral decree of 18/06/2024)
• 🔵 03/2024 → 03/2024 – Floods (prefectoral decree of 15/04/2024)
• 🔵 09/2024 – Floods (prefectoral decree of 13/10/2024)
• 🔵 10/2024 → 10/2024 – Floods (prefectoral decree of 15/12/2024)

Expert reading: 5 droughts and 22 floods. Clusters (several decrees close together) flag up 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 way forward is an action against the seller.

The official clay classification (GéoRisques/BRGM)

The GéoRisques platform (BRGM) classifies Fréjus 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. Worth noting: radon potential class 3 across the commune (IRSN/GéoRisques data) – a health-and-building watch point in the affected zone.

This classification completes the decree history above: the hazard rating says what can happen, the decrees say what has already happened. A house rated “high exposure” that has come through one or more dry summers carries a risk of damage that is all the better documented.

What the official clay mapping says

The GéoRisques platform (BRGM) classifies Fréjus 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. Worth noting: radon potential class 3 across the commune (IRSN/GéoRisques data) – a health-and-building watch point in the affected zone.

This classification completes the decree history above: the hazard rating says what can happen, the decrees say what has already happened. A house rated “high exposure” that has come through one or more dry summers carries a risk of damage that is all the better documented.

Local rainfall: the trigger

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

• 2019: 1,126 mm · 2020: 629 mm · 2021: 670 mm · 2022: 580 mm · 2023: 649 mm · 2024: 1,142 mm
• Average over the period: 799 mm/year, driest year: 2022 (580 mm)
• Four consecutive deficit years (2020-2023): 629 mm, 670 mm, 580 mm, 649 mm
• Then 2024 rebounds to 1,142 mm, i.e. +43%

Why this alternation concerns you directly: shrink-swell plays out in two stages. First the drought dries out the clay at depth: the ground shrinks, first cracks appear. Then the return of the rain abruptly rehydrates the ground: swelling, differential movement. If your house sits on shallow foundations – the case for most villas built between 1970 and 2000 in Fréjus – expect cracks to appear with a 12 to 24-month lag after the dry spell, not immediately.

Cracks in Fréjus: the signs that should worry you

• A stair-step crack, passing through the wall, open by more than 2 mm
• A crack that evolves (fit a plaster or glass tell-tale and check it at intervals of a few months)
• Other signals: doors and windows sticking, tiles splitting diagonally, render bulging
• A house on clay soil, trees close by, a drain that no longer does its job

With 5 drought prefectoral decrees recognised in Fréjus, as soon as two or three of these signs build up at your property, call in an expert before any repair – and before any buying or selling decision. Filling an active crack without a diagnosis solves nothing: it comes back.

Buying or selling a cracked house in Fréjus: the legal side

Between the recent drought decrees and the number of transactions underway, quite a few properties are changing hands with damage kept quiet. If you are the buyer and discover cracks after signing, you have two levers:

• Hidden defect (article 1641 of the Code civil): serious cracks, invisible at the viewing, predating the sale → price reduction or cancellation of the sale, to be claimed within 2 years of discovery
• Fraud (dol) (article 1137): the seller knew and concealed the damage → cancellation and damages, within 5 years; the commune’s GASPAR decree then helps underpin your file

To launch either of these procedures, appoint a property-law solicitor (avocat) – and arm yourself with an expert report that dates and qualifies the damage: this is the piece that swings a file.

How a drought/clay survey unfolds in Fréjus

• Technical visit: crack survey and classification, crack-width measurements, functional damage
• Context analysis: clay zone, the commune’s natural disaster declaration (Cat Nat) history (5 drought decrees), local drought sequences
• Costing of works: underpinning, injections, drains – with several scenarios
• A written report, usable by the insurer or the solicitor

For an on-site survey: building expert in Fréjus.

Independent expert, with no ties to any building contractor. Request a visit in Fréjus – see also our complete RGA and Cat Nat guide for 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 obligation, stemming from ELAN law no. 2018-1021, article 68 (decree no. 2019-495 of 22 May 2019), applies particularly to Fréjus (high exposure in the BRGM classification).

• What it changes for building: the soil survey is no longer an option – the ELAN law makes it compulsory in an exposed zone for every sale of building land and every 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 soil 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 fraud (dol).
• The link with the data above: Fréjus combines high exposure with a well-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, damage surveys on clay ground, counter-expertise. Request a consultation.

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 obligation, stemming from ELAN law no. 2018-1021, article 68 (decree no. 2019-495 of 22 May 2019), applies particularly to Fréjus (high exposure in the BRGM classification).

• What it changes for building: the soil survey is no longer an option – the ELAN law makes it compulsory in an exposed zone for every sale of building land and every 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 soil 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 fraud (dol).
• The link with the data above: Fréjus combines high exposure with a well-documented history of drought decrees. Building or buying here without checking the nature of the ground means building on a known and measured risk.

Frequently asked questions

Is Fréjus in an at-risk clay zone?

Yes. The Alpes-Maritimes and the Var are very broadly covered by the clay shrink-swell (RGA) hazard (BRGM map, viewable on georisques.gouv.fr). In Fréjus, no drought prefectoral decree recognised to date: the BRGM exposure is real, but the Cat Nat route is not yet established there.

Can a cracked house in Fréjus be compensated under the natural disaster scheme?

Only if your damage dates from a period covered by a decree (the latest recognised: 2003, 2021, 2023, 2024) and if you declared the loss to your insurer within 30 days of the decree. If not, what remains is the action against the seller – and there, precisely dating the damage through a survey becomes the decisive factor.

Can the figures on this page be checked?

Yes, and you should: the decrees come from the GASPAR database (Journal officiel, open data sets, 2025 update), the rainfall from Open-Meteo weather archives for the Fréjus grid. Cassini Expertise merely reports them, without adjusting anything – cross-check them against your own situation before deciding.

This week’s drought watch (as at 04/10/2026)

In the commune: recent rain (3 days ago). Rainfall over the last 30 days: 8 mm, against roughly 57 mm expected at this time of year – an 86% deficit.

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

Where do the rains stand? (as at 05/10/2026)

In the commune: recent rain (4 days ago). Rainfall over the last 30 days: 8 mm, against roughly 59 mm expected at this time of year – an 86% deficit.

A sustained deficit over this window, especially in the growing season, often precedes by a few weeks the drop in the water table shown 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 (4 days ago). Rainfall over the last 30 days: 95 mm, against roughly 69 mm expected at this time of year – a 38% surplus.

A sustained deficit over this window, especially in the growing season, often precedes by a few weeks the drop in the water table shown 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: recent rain (2 days ago). Rainfall over the last 30 days: 98 mm, against roughly 80 mm expected at this time of year – a 22% surplus.

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

The aquifer against its historic record: what do 35 years of measurements say?

The reference piezometric station for the area (002LEHE) has been monitoring the aquifer since 1990 – 35 years of records. As at 02/10/2026, the average level over the last thirty days is 1.18 m NGF (French ordnance datum). Across the whole record, the aquifer has spent only 8.6% of its time below this level: a very low level, rarely reached in the station’s history.

• Last equivalent episode: 03/12/2023 – 2.8 years ago
• Frequency: 25 similar episodes recorded since 1990, i.e. an annual return on average – in hydrologists’ language, a rare event
• Historic minimum: 0.95 m NGF, reached on 26/09/1990

This long memory changes how the risk is read: a low level is not just a 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 fresh 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.