What damage is really covered by ten-year (décennale) liability?

"What exactly does my ten-year cover protect me for?" It's the question every tradesperson ends up asking, often the moment a client reports a defect. This article is aimed at construction professionals who want to understand precisely what their ten-year (décennale) liability covers — and where that cover stops.

The principle: "serious" and "hidden" damage

For damage to be covered by ten-year liability, it must meet several criteria at once:

It must appear after the works are handed over
It must be sufficiently serious within the meaning of article 1792 of the French Civil Code (Code civil)
It must not have been visible and accepted at handover (otherwise it falls under the guarantee of perfect completion / garantie de parfait achèvement)
It must concern a structural work or a piece of equipment inseparable from the structure

The purpose of this logic is to protect the client against major defects that only emerge over time: cracks that worsen, damp that appears after two winters, a built-in boiler that fails after five years.

Category 1: harm to the structural soundness of the works

These are the most emblematic cases. They involve defects that threaten the physical durability of the building or one of its essential parts. Typical examples:

Structural cracks running through a load-bearing wall
Foundation subsidence caused by a faulty soil survey or formwork
Partial collapse of a roof frame or a slab
Major deformation of a load-bearing floor
Detaching render affecting the waterproofing or the stability of a façade

The decisive criterion is that the structural soundness is called into question, even progressively. A superficial, cosmetic shrinkage crack does not fall under ten-year liability; a progressive crack running through the masonry does.

Category 2: unfitness for intended purpose

This is the broadest category — and the most debated in case law. A structure is "unfit for its intended purpose" when it no longer performs the function for which it was designed, even if it is still physically standing.

Common cases recognised by the courts:

Seepage making a roof no longer watertight or a cellar unusable
Chronic damp making a home unhealthy to live in
Major thermal insulation defect (a home impossible to heat under normal conditions)
Failure of built-in central heating making the home uninhabitable in winter
Acoustic nuisances exceeding regulatory thresholds
Subsiding floor tiles making a floor dangerous to walk on

The judge assesses the seriousness of the defect case by case. Mere discomfort is not enough; the normal use of the property must be compromised.

Category 3: inseparable equipment

Article 1792-2 of the French Civil Code (Code civil) extends ten-year liability to equipment that is integral to the works. The criterion: removing it would damage or require the removal of a constituent part of the building.

Examples of equipment considered inseparable:

A boiler sealed into a masonry boiler room
Underfloor heating embedded in the slab
Pipework built into the walls
A lift integrated into a masonry shaft
A mechanical ventilation unit (VMC) whose ducts are embedded in the structure

Conversely, a wall-mounted radiator, a motorised roller shutter or a standalone hot water tank are removable equipment: they fall under the two-year guarantee (garantie biennale), not ten-year liability.

A few common real-world cases

To help you place your own projects, here are real situations decided by the courts:

Roof re-done, seepage 3 years later → ten-year liability (unfitness for intended purpose)
Tiles detaching heavily after 18 months → ten-year liability if there is a laying defect linked to the substrate; two-year guarantee if purely cosmetic
Heat pump failure, integrated into the heating system → ten-year liability if it is inseparable
Paint flaking on the surface → neither ten-year nor two-year: the manufacturer's commercial warranty
Roller shutter that no longer goes down → two-year guarantee (garantie biennale)
Load-bearing wall cracking after a structural alteration → ten-year liability (harm to structural soundness)

What ten-year liability does not cover

As a reminder, ten-year liability does not cover:

Purely cosmetic defects (paintwork, jointing, alignment)
Normal wear over time
Damage caused by a lack of maintenance or abnormal use by the client
Removable equipment (covered by the two-year guarantee)
Claims resulting from an event of force majeure

For a detailed list, read our article on the exclusions of ten-year (décennale) liability.

How does a claim proceed?

When a client reports a potential ten-year claim, the typical procedure is as follows:

Filing by the client with their Dommage Ouvrage insurer (if they have one) and with your insurer
Adversarial expert assessment to qualify the defect
Decision to cover the claim: whether or not it qualifies as a ten-year defect
Compensation or carrying out the remedial works
Any recourse between insurers if several firms are involved

Your role is to cooperate with the expert, to provide the project documents (quotes, plans, handover report) and never to work on the structure without your insurer's prior agreement.

In summary

Ten-year liability covers three families: structural soundness, unfitness for intended purpose, inseparable equipment
The damage must be serious and appear after handover
Cosmetic defects, normal wear and removable equipment are not covered
Where there is doubt over how to qualify the damage, the adversarial assessment decides

Need support?

A reported claim, a doubt over the extent of your cover, or a complex project ahead? Our team of brokers supports you in choosing your ten-year (décennale) insurance and analysing your cover. Request a personalised quote or get in touch with an adviser.