By Garen Ajderhanyan · 9 August 2026 · 6 min read
In brief
To sell a property in France, the vendor provides the purchaser with a dossier de diagnostics techniques (DDT), annexed to the promesse and then to the acte de vente. Its composition depends on the age and location of the property: DPE, asbestos, lead, electricity, gas, risk assessment, termites in areas concerned, sanitation where applicable, and loi Carrez measurement in copropriété. The DPE is mandatory from the publication of the advertisement. The diagnostics are prepared by a certified diagnostiqueur, in principle at the vendor's expense.
Which diagnostics are required to sell?
The dossier de diagnostics techniques, the DDT, as notaires call it, brings together all the assessments and reports that the vendor must provide to the purchaser. Depending on the property, it includes the DPE, the asbestos report, the lead exposure risk assessment (CREP), the condition report for the internal electrical installation, the gas installation report, the risk and pollution assessment (ERP), the termite report in areas declared by prefectoral order, the non-mains sanitation inspection where applicable, and the loi Carrez measurement for a lot in copropriété.
Not all these documents concern all properties. Asbestos applies to buildings of a certain age, lead to the oldest buildings, termites only to areas defined by order, electricity and gas to installations that have exceeded a certain age. The exact composition of the dossier must be verified on a case-by-case basis, on Service-public.fr or with a certified diagnostiqueur, this is the first step I recommend before any sale.
Is the DPE mandatory?
Yes, and it is the only diagnostic required from the advertisement. The DPE classifies the dwelling from A to G according to its energy consumption and greenhouse gas emissions; the rating must appear on every sale advertisement, in agency windows as well as online. At La Gazette, we still see advertisements published with the mention 'DPE en cours': this is a sale that starts poorly.
The DPE is moreover opposable: the purchaser may rely on the information it contains. It is prepared by a certified diagnostiqueur, never by the vendor himself. The rule is the same for a seafront flat and for a house in the hills.
What is the loi Carrez?
The loi Carrez requires the private floor area of the lot to be stated in any preliminary contract and deed of sale for a property in copropriété. It defines a precise measurement method, which excludes in particular areas under low ceilings, balconies and cellars.
If the actual floor area proves to be less than that stated beyond the margin permitted by law, the purchaser has recourse to a price reduction. The vendor may measure himself, but entrusting the operation to a professional remains the prudent course: a measurement error is paid for after the sale.
Who carries out the diagnostics?
Most diagnostics, DPE, asbestos, lead, electricity, gas, termites, must be prepared by a diagnostiqueur certified by an accredited body, covered by professional indemnity insurance and independent of the vendor as well as the agency. An official directory of certified diagnostiqueurs may be consulted online.
Two notable exceptions: the risk assessment (ERP) may be completed by the vendor from prefectoral information available online, and loi Carrez measurement does not require certification. The costs of the dossier are in principle borne by the vendor.
When to arrange them?
The DPE first, even before drafting the advertisement, since the rating must appear on it. The rest of the dossier is best assembled before signing the promesse or the compromis: it is at this stage that the purchaser becomes aware of it and that his cooling-off period runs.
Each diagnostic has its own period of validity, which varies according to its nature and sometimes according to its result. Rather than remembering figures that change with legislation, check the periods in force on Service-public.fr or ask your diagnostiqueur for a validity schedule: a document expired on the day of completion will have to be redone.
Frequently asked questions
- Who pays for property diagnostics?
- In principle, the vendor. It is he who must provide a complete dossier de diagnostics techniques to the purchaser; diagnostiqueurs' fees are freely set, so it is useful to compare several quotations.
- What does the vendor risk if a diagnostic is missing?
- The absence of a mandatory diagnostic deprives the vendor of the exemption from the guarantee against hidden defects on the point concerned. Depending on the case, the purchaser may request a price reduction, or even rescission of the sale. In practice, the notaire does not execute the deed without a complete dossier.
- Must the DPE appear in the advertisement?
- Yes. The energy and climate ratings of the DPE must appear on every sale advertisement, whatever the medium. It is the only diagnostic required from the marketing stage.
- Are the diagnostics the same for all dwellings?
- No. The composition of the dossier depends on the age of the building, its location and its status: the loi Carrez concerns only copropriété, termites only areas covered by order, non-mains sanitation properties not connected to the public network.
- How long does a diagnostic remain valid?
- The period varies according to the diagnostic and sometimes according to its result. The periods in force are summarised on Service-public.fr; a certified diagnostiqueur will tell you which of your documents need to be redone before the sale.
References
The author
Garen AjderhanyanEditor of La Gazette de la Promenade
Editor of La Gazette de la Promenade. He writes on Riviera property and the art of living, from Nice.