Real estate diagnosis: state of the gas interior installation
Verified 17 September 2026 - Public Service / (Prime Minister)
In which case must a condition of the internal gas installation, also called gas diagnosis ? The condition of the indoor gas installation is a diagnosis that assesses the risks that may endanger the safety of people. It must be provided by the landlord or the salesman and be given to the future tenant or purchaser when the gas plant is more than 15 years old. Here is the information you need to know.
Rental
The owner who rents a apartment or a detached house of which the gas installation has more than 15 years must provide a gas diagnosis to the future tenant.
Diagnosis should be made by a diagnoser responding to certain criteria, including certification.
It is possible to use a directory to search for a certified diagnoser:
Search for a certified real estate diagnoser or check the certificates of its diagnoser
The gas diagnosis is carried out in the private parts of the dwelling and its outbuildings.
It shall describe the following information:
- Condition of fixed appliances for heating and producing domestic hot water or using a heat engine, supplied with gas
- Condition of fixed gas supply pipes and their accessories
- Arrangement of the premises where the gas appliances operate, allowing the ventilation of these premises and the evacuation of combustion products.
The gas diagnosis must be carried out in accordance with a regulated model and method.
Please note
The gas diagnosis is carried out without dismantling elements of the installations.
The gas diagnosis must be integrated into the technical diagnostic record (DDT).
It must be given to the future tenant at the time of signing the lease.
The gas diagnosis must have been carried out since under 6 years old on the date of signature of the lease.
However, if the gas installation has already been modified or completed and has been the subject of a certificate of conformity, generally delivered by the installer, it is not necessary to have a gas diagnosis carried out. To be valid, the certificate of conformity must have under 3 years old on the date of signature of the lease. The certificate of conformity must come from one of the 3 organizations currently approved by the Minister responsible for housing: Qualigaz, Dekra, Copraudit.
FYI
If a gas diagnosis has already been carried out for the purposes of the sale of the housing, it can be attached to the lease in case of rental if it has been carried out for less than 6 years.
The penalties vary depending on the people involved.
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Lessor
The landlord may be held liable if he does not transmit the gas diagnosis or if he provides inaccurate information in the rental announcement, misleading the future tenant.
In addition, the lessor may also be fined €1,500 if using an uncertified diagnoser (€3,000 in case of recurrence).
Diagnostic
If the diagnoser commits a fault by not complying with the regulations to carry out the gas diagnosis (for example, erroneous diagnosis), the tenant can appeal to the judicial court of the location of the property to request damages and interest.
In addition, the diagnoser may be fined €1,500 if practicing without certification (€3,000 in case of recurrence).
Sale
The owner who puts a apartment or a detached house of which the gas installation has more than 15 years must provide a gas diagnosis to the future purchaser.
Diagnosis should be made by a diagnoser responding to certain criteria, including certification.
It is possible to use a directory to search for a certified diagnoser:
Search for a certified real estate diagnoser or check the certificates of its diagnoser
The gas diagnosis is carried out in the private parts of the dwelling and its outbuildings.
It shall describe the following information:
- Condition of fixed appliances for heating and producing domestic hot water or using a heat engine, supplied with gas
- Condition of fixed gas supply pipes and their accessories
- Arrangement of the premises where the gas appliances operate, allowing the ventilation of these premises and the evacuation of combustion products.
The gas diagnosis must be carried out in accordance with a regulated model and method.
Please note
The gas diagnosis is carried out without dismantling elements of the installations.
The gas diagnosis must be integrated into the technical diagnostic record (DDT).
It must be given to the future purchaser at the time of signature of the promise to sell or the authentic deed of sale.
The gas diagnosis must have been carried out since under 3 years old on the date of the promise to sell or the authentic deed of sale.
However, if the gas installation has already been modified or completed and has been the subject of a certificate of conformity, generally delivered by the installer, it is not necessary to have a gas diagnosis carried out. To be valid, the certificate of conformity must have under 3 years old on the date of the promise to sell or the authentic deed of sale. The certificate of conformity must come from 1 of the 3 organizations currently approved by the Minister responsible for housing: Qualigaz, Dekra, Copraudit.
The penalties vary depending on the people involved.
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Seller
The seller may incur liability if he does not transmit the gas diagnosis. In this case, it cannot be exempted from the guarantee of hidden defects (non-visible defects).
It may also be punished by a fine of €1,500 if using an uncertified diagnoser (€3,000 in case of recurrence).
Diagnostic
If the diagnoser commits a fault by not complying with the regulations to carry out the gas diagnosis (for example, erroneous diagnosis), the purchaser can appeal to the judicial court of the location of the property to request damages and interest.
In addition, the diagnoser may be fined €1,500 if practicing without certification (€3,000 in case of recurrence).
Search for a certified real estate diagnoser or check the certificates of its diagnoser
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For more information on this subject, you can contact Allô Service Public.
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