Reflex no. 1: tell your agent everything, from the moment the mandate is signed
This is one of the subjects I systematically raise with my seller clients as soon as I take on a property: tell me everything, right from the start. A garage converted into a living space, an extension built without planning notification, a garden shed put up by eye… these situations are very common, and rarely mentioned spontaneously by sellers — often because they don’t even realise it could be an issue.
The risk, if these matters are not anticipated: they come to light when the notaire reviews the file, once an offer has already been made — and that is the worst possible moment to discover them. I have handled a sale where the lack of a declaration for a garage conversion only surfaced at that stage: the result was a price renegotiation in the middle of the pre-sale agreement phase, after the buyer had already made their offer.
My recommendation, as an estate agent: together, from the moment the mandate is signed, we list the property’s complete history — works, extensions, insurance claims, current guarantees — and I inform the buyer from the very first viewings. A sale that is fully transparent from the start almost always runs smoothly through to signing at the notaire’s office.
A few useful benchmarks for assessing undeclared works (under French planning rules):
Under 5 m²: no planning formality is required (a simple garden shed, for example).
Between 5 and 20 m² (up to 40 m² in urban zones where the municipality has a local plan): a prior works declaration is required.
Above 20 m² (or 40 m² depending on the zone): a building permit is mandatory.
A change of use (a garage converted into a bedroom, for example), even without any extension, must also be declared.
With that point of vigilance established, here is the list of documents to prepare — and why each one matters.
The DAACT (declaration certifying completion and conformity of works)
This is the document owners most often have in their possession, since it must be filed with the town hall within 90 days of the end of the building work. The DAACT certifies that the works are finished and comply with the building permit that was granted.
Keep safe: the filing receipt, which serves as proof of the date it was submitted to the town hall.
The certificate of non-contestation of conformity: the document to anticipate
This is where it gets more complicated, and there are in fact two distinct time limits not to be confused.
- The inspection period: 3 months (5 months in some cases)
Once the DAACT has been filed, the town hall has 3 months — extended to 5 months in certain protected areas, near historic monuments or in risk zones — to inspect and, if necessary, contest the conformity of the works. Throughout this period, the town hall may carry out an on-site inspection to check that the construction matches what was authorised. Until this period has expired, the town hall cannot issue anything: it is still entitled to contest, so no certificate of “non-contestation” makes sense before the 3 (or 5) months are up.
- The issuance period on request: 15 days
Only once this inspection period has expired, with no contestation from the town hall, is conformity tacitly acquired. This non-contestation is never sent automatically, however: it must be expressly requested from the planning department (ideally by registered letter with acknowledgement of receipt, stating the DAACT filing date and the permit number). It is only from this request — made after the 3 or 5 months have expired — that the town hall is legally required to issue the certificate within 15 days.
To be clear: you cannot obtain this certificate within 15 days of filing the DAACT. The 15-day countdown only starts after the 3 (or 5) months of the inspection period, and only if the request has been made at that point. In practice, between filing the DAACT and actually obtaining the document, you should therefore allow an overall period of around 3 months — and many town halls, short of resources, do not strictly meet the 15-day deadline either.
Why anticipate it as soon as the property goes on the market? Because this document is increasingly demanded by notaires as a matter of course, and this overall 3-month period (or more) can delay the signing if you leave it too late. It is best to start the process as soon as you decide to sell — and ideally as soon as the 3-month inspection period comes to an end — without waiting for the pre-sale agreement.
The other documents to gather
The building permit and all its supporting documents (plans, decision).
The works acceptance report, signed with the builder or contractors: it is this document, not the DAACT, that marks the starting point of the ten-year structural guarantee.
The damage-to-works insurance certificate, if taken out (it greatly simplifies any claim during the guarantee period).
The ten-year guarantee certificates of the professionals who carried out the works, and the history of any declared claim (water damage, cracks, etc.), even if repaired.
The construction contract (CCMI) or the invoices from the various trades, depending on how the house was built.
The usual technical surveys (energy performance, electricity, gas where applicable, etc.), as for any sale.
This article is for information purposes and does not replace the advice of a notaire for the full review of your file.
