The French decennial warranty covers damage that compromises the solidity of the works or renders them unfit for their purpose, for ten years from acceptance. It operates as of right: the employer does not have to prove fault. The builder escapes it only by establishing an external cause.
Two criteria, and only two
Article 1792 of the Civil Code runs to two sentences, but those two sentences govern the whole of construction litigation. Every builder of works is liable as of right, to the employer or the purchaser of the works, for damage, even resulting from a defect in the ground, which compromises the solidity of the works or which, affecting them in one of their constituent parts or one of their items of equipment, renders them unfit for their purpose. And there is no liability if the builder proves that the damage arises from an external cause.
The first criterion, impairment of solidity, is easily grasped: foundations that move, a cracked frame, a sagging roof structure, a landslip beneath the works. The second, unfitness for purpose, is what fuels the arguments, because it requires the purpose of the works to be defined before saying whether they are unfit for it. A house is intended to be lived in: recurrent water ingress in the bedrooms, a dangerous electrical installation, sound insulation so poor that sleep is impossible, drainage that backs up, all of this affects the purpose without any wall threatening to fall.
The courts will even reason in terms of risk. An established risk of fire in a building roof makes the building unfit for its purpose in itself, the Third Civil Chamber held in a case on internal combustion of photovoltaic panel connection boxes, where no fire had actually started (Cass. 3e civ., 21 September 2022, no. 21-20.433, reported). There is therefore no need to wait for the loss before acting, which bears directly on strategy: a threatened defect is enough.
Who is liable, and for what
The list of debtors is wider than most employers think. Article 1792-1 treats three categories of person as builders. Any architect, contractor, technician or other person bound to the employer by a building contract. Any person who sells, after completion, works that he built or had built, which covers the developer but also the private individual who resells within ten years the house he had built. And any person who, although acting as agent of the owner, performs a role equivalent to that of a building contractor.
The manufacturer is not outside the net. Article 1792-4 makes him jointly and severally liable for the obligations imposed on the contractor where he designed and produced works, part of works or an item of equipment to meet, in working order, precise requirements determined in advance, and the installer put it in place without modification and in accordance with the manufacturer rules. The importer of a product made abroad, and anyone who presented it as his own by putting his name or mark on it, are treated as manufacturers. In defective materials cases this provision allows the chain to be traced back.
The subcontractor is not bound by the decennial warranty, for want of a contract with the employer, but he is not out of reach: article 1792-4-2 subjects claims against him to a ten year limitation from acceptance for damage falling under articles 1792 and 1792-2, and two years for damage affecting the equipment covered by article 1792-3. His liability remains tortious or contractual as the case may be, but the time window mirrors that of the decennial warranty.
As of right, and the only way out
Saying that liability arises as of right means the employer has nothing to prove beyond the defect, its seriousness and its connection to the works. No fault to establish, no negligence to demonstrate. That presumption is what radically distinguishes the decennial warranty from ordinary contractual liability, and it explains why defences concentrate on two grounds: the characterisation of the defect, and external cause.
External cause covers force majeure, the act of a third party and the act of the employer. The last is the most frequently argued: wrongful interference by a notoriously competent employer, a material imposed against the contractor advice, manifest failure to maintain equipment, a modification made after acceptance. The burden is on the builder, and the demonstration must be complete, a partial contribution by the employer exonerating him only in proportion.
Items of equipment, a minefield
The regime for equipment has become the main source of litigation, and it rests on four rules that sit together badly.
Article 1792 covers items of equipment where the defect renders the works unfit for their purpose. Article 1792-2 extends the presumption to damage affecting the solidity of items of equipment forming an indissociable whole with the works of servicing, foundation, framing, enclosure or roofing, indissociability being defined by the impossibility of removing, dismantling or replacing the item without damage or removal of material. Article 1792-3 subjects other items of equipment to a warranty of proper working order of at least two years. And article 1792-7 excludes from articles 1792, 1792-2, 1792-3 and 1792-4 items of equipment, accessories included, whose exclusive function is to allow a professional activity to be carried on in the works.
That last provision cuts sharply in photovoltaic cases. The Third Civil Chamber quashed a court of appeal decision that had applied the decennial warranty to a solar installation on the ground that it also formed the roof of the building, without establishing that the panels causing the damage, although fixed to steel trays forming the roof, were not items devoid of any enclosing or roofing function whose exclusive purpose was a professional activity of producing and selling energy (Cass. 3e civ., 19 February 2026, no. 24-10.702). In other words, an operator selling his electricity must expect article 1792-7 to be raised against his claim.
Two developments have further narrowed the field. First, damage affecting an item not intended to function, added to an existing building, falls exclusively under ordinary contractual liability, whatever its seriousness: floor tiling and plasterboard partitions are not intended to function (Cass. 3e civ., 13 July 2022, no. 19-20.231, reported). Second, and above all, the Court abandoned in 2024 its 2017 case law on equipment installed on existing buildings, a subject important enough to deserve separate treatment.
Ten years, and what exactly that period covers
The duration is set by article 1792-4-1: any person whose liability may be engaged under articles 1792 to 1792-4 is discharged after ten years from acceptance of the works, or on expiry of the two year period for the warranty of proper working order. This period is both a period of exposure and a period for suing: the defect must appear within the ten years, and proceedings must be brought within the same time.
An urgent application for the appointment of a court expert interrupts the period; a simple out of court claim does not. That is the main cause of time bars met in practice: an employer who has exchanged letters for two years with the company, then with the insurer, then with a private expert, and who applies to the court eleven years after acceptance, has no claim left, whatever the reality of the defect. The date of acceptance, once again, governs everything.
Beyond the statutory warranties, article 1792-4-3 confines other liability claims against builders and their subcontractors within ten years of acceptance. An employer who thinks he can fall back comfortably on the ordinary law therefore finds an identical time barrier.
Who pays: compulsory insurance and its blind spots
Article L. 241-1 of the Insurance Code requires every person whose decennial liability may be engaged to be covered by insurance, and to produce proof at the opening of any site that a policy is in place. The policy is deemed to contain a clause maintaining cover for the duration of decennial liability, which neutralises claims made clauses.
The trap is not the existence of the policy, it is the list of declared activities. A company insured for masonry that also builds the roof frame is not covered for the frame, and the insurer will decline on that ground. The Third Civil Chamber has nonetheless made clear that the reasoning cannot be purely proportional. In a case where the court of appeal had limited the insurer cover to 9.06 per cent of the loss, the share of the masonry works in the total contract price, although the defects required the house to be demolished and rebuilt, the Court quashed the decision under article L. 241-1: it had to be examined whether the covered defects on their own justified demolition and reconstruction (Cass. 3e civ., 12 March 2026, no. 24-10.927).
The lesson is directly operational. Faced with an insurer proposing an apportionment based on the price of the trade packages, the expert evidence must be directed at a precise question: would the remedial solution have been the same if only the covered defect had existed. If the answer is yes, there is no room for proportional reduction.
How to bring a decennial claim without knocking on the wrong door
The useful sequence has four steps. Assemble the documents first: the contract, the record of acceptance, each participant insurance certificate, correspondence, dated photographs. Then notify the loss to the damage to works insurer, who is required to respond within short periods and whose silence carries sanctions. In parallel, or failing that, apply urgently for a court expert, the only measure that interrupts limitation and that allows every participant to be joined. Finally bring the substantive claim, against the builders and their insurers, jointly and severally where several contributed to the damage.
Joining every participant from the outset is the point on which cases are most often lost. An employer who sues only the main contractor, then discovers during the expert process that the defect originates with a subcontractor or a manufacturer, finds himself having to start a second set of proceedings, sometimes out of time.
Frequently asked questions
Does the decennial warranty cover cosmetic defects?
In principle no. A defect of appearance affecting neither solidity nor purpose falls under the warranty of perfect completion if it was reserved or notified within the year, and under the ordinary law thereafter. The line shifts where the cosmetic defect reveals a technical problem, cracking for instance, or where the extent of the deterioration deprives the works of their use.
Are new build and renovation treated the same way?
No, and this is a constant source of misunderstanding. Renovation works fall under the statutory warranties only if they themselves constitute works, or if they are incorporated into the existing building to the point of becoming technically indivisible from it. A simple item of equipment fitted to an existing building follows a different regime.
Is the seller of a house less than ten years old liable?
If he built it or had it built, yes, as a builder within the meaning of article 1792-1. In the case of a sale of a building to be constructed, article 1646-1 makes him subject to the same obligations as building contractors, and those warranties benefit successive owners.
What if the company has disappeared or is in liquidation?
The disappearance of the company does not extinguish its insurer cover, which can be claimed on directly. That is precisely the function of compulsory insurance. The certificate must therefore be obtained, the insurer identified and joined to the proceedings, including where a liquidator has already been appointed.
Do the ten years run from the end of the site works?
No, from acceptance, which may come before or after physical completion and which may be tacit. The date the works finished, the date of the last invoice and the date of the completion declaration at the town hall are indications, not the starting point.
Can the decennial warranty and contractual liability be combined?
Not for the same defect falling under the decennial warranty: the statutory regime is exclusive. The ordinary law resumes for what falls outside the statutory warranties, in particular intermediate damage arising from proven fault, within the period of article 1792-4-3.