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See a real case. Facade cracks and rainwater drainage – Cannes : 16 cracks catalogued, drainage review, clay shrink-swell context.
Overview of the Court Ruling
In a ruling dated 14 September 2023 (appeal no. 21-22.429), the Third Civil Chamber of the French Supreme Court (Cour de cassation) clarified the conditions for triggering the ten-year builder’s warranty for cracks that appeared after a period of drought. In this case, homeowners had sued their builder after significant cracks appeared in the walls of their house, several years after handover. The the court expert had concluded that the damage stemmed from clay shrink-swell (RGA), worsened by insufficiently deep foundations. The Court of Appeal had dismissed the claim, ruling that the causal link with the clay soil had not been established. The Cour de cassation overturned that ruling, holding that lower courts must examine whether the damage, by its nature and severity, compromises the structural soundness of the building or renders it unfit for its intended purpose, and that the expert report had sufficiently demonstrated the link between the RGA and the cracks.
Technical Analysis
Clay shrink-swell is a natural phenomenon: clay soils shrink during periods of drought (loss of water) and swell during rainfall. This differential movement can cause settlement and heave, generating cracks in structures. To establish causation, the expert must:
- Analyse the soil composition (laboratory testing, water content, Atterberg limits);
- Study rainfall records and drought indices;
- Examine the foundations (depth, type, presence of expansion joints);
- Characterise the cracks (orientation, width, progression over time).
Shallow foundations on clay soil, without adaptation (sufficient depth, raft foundation, etc.), are a common cause of damage.
Case Study: Cassini Expertise Steps In
Mr and Mrs Dupont, owners of a detached house built in 2018, noticed vertical and diagonal cracks in the load-bearing walls in 2022, which kept widening. Their insurer refused to cover the damage, claiming a lack of maintenance. They hired Cassini Expertise for an amicable assessment, followed by a court-ordered expert report.
Observed damage: The expert recorded cracks 2 to 5 mm wide, running through the render and facing, with a 3 mm offset. Doors and windows showed signs of misalignment and difficulty opening.
Measurements and analysis: The expert carried out soil surveys (pressuremeter tests, water content), topographic surveys (foundation levelling), and analysed weather data (2019-2022 drought). Foundations were found to be shallow (0.60 m) despite the site being classified as a high-risk RGA zone under official mapping.
Expert report: The expert concluded that the cracks were a direct consequence of clay shrink-swell, worsened by insufficient foundation depth. Repair costs (underpinning, micropiles) were estimated at €45,000.
Court outcome: Based on the report, the court held the builder liable under the ten-year warranty (damage compromising structural soundness). The Court of Appeal upheld the ruling, and the Cour de cassation dismissed the builder’s final appeal.
Key Takeaways
- For homeowners: in clay-prone areas, require a preliminary soil survey (G1, G2) and appropriately adapted foundations (depth > 0.80 m, raft foundation, expansion joints).
- For builders: comply with industry standards (DTU 13.11, NF P 94-261) and inform clients of the risks.
- Forensic expertise is essential to establish the causal link between the natural phenomenon and the construction defect.
Are you a lawyer or a party to a court-ordered expert assessment? Cassini Expertise supports you in drafting expert submissions, attending adversarial meetings, and making the most of the expert report. Discover our support services →
Frequently Asked Questions
What are the conditions for triggering the ten-year builder’s warranty for RGA-related cracks?
You must show that the cracks compromise the structural soundness of the building or render it unfit for its intended purpose, and that they stem from a construction defect (e.g. inadequate foundations) rather than an act of force majeure.
How does the expert prove the link between the cracks and clay shrink-swell?
Through soil testing (identification, water content), analysis of climate data, examination of the foundations, and characterisation of the cracks (orientation, progression).
What is the time limit for taking legal action after cracks appear?
The ten-year warranty runs from the date the works are handed over. Legal action must be brought within 10 years of handover, but it is advisable to act as soon as the damage appears.
Can I get compensation without a court-ordered expert report?
An amicable expert assessment may be enough for a negotiation, but in a dispute, a court-ordered expert report is often necessary to obtain a favourable ruling.
📅 Updated on 14/08/2026 – By Cassini Expertise, independent building expert serving 06, 83 & 13. Free quote: 04 22 46 06 04.
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Survey carried out by Frédéric Faucouneau, independent building expert – Antibes, Alpes-Maritimes (06), Var (83), Bouches-du-Rhône (13). Find out more
📅 Last updated 02/11/2026 - Cassini Expertise, independent building expert – departments 06, 83 and 13.