Entrepreneur's Duty to Advise: When the Quote Does Not Match the Planning Permission

You have just signed a quote for the construction of your house in Wasquehal. The work begins, everything is fine. But one day, you receive a letter from the town hall: your planning permission does not correspond to the work undertaken. Who is responsible? The entrepreneur who prepared the quote? Or you, the building owner, who should have checked? This is exactly the question the Court of Cassation had to decide in a case that is now a precedent.

Every year, hundreds of owners find themselves in this situation: an estimate that underestimates the necessary work, or that provides for structures not in conformity with the planning permission. The consequences can be serious: stop-work order, fine, obligation to demolish, even legal proceedings. What does the law say? Does the entrepreneur, as a professional, have an obligation to ensure that his quote is consistent with the planning authorisation?

The answer is yes, and it is unequivocal. In a judgment of 2 October 2002, the Court of Cassation ruled that an entrepreneur incurs liability if he does not verify that the estimate he provides is consistent with the planning permission. Even if he did not participate in obtaining that permission, he must, by virtue of his duty to advise, alert the client to any inconsistencies. Let us analyse this decision and see what it changes for you.

The Facts: A Story Like Those That Happen Every Day

Mr and Mrs X, owners in Tourcoing, wish to have an individual house built. They entrust the execution of the works to the company Deixonne, a construction firm. An estimate is drawn up, on the basis of which Mr and Mrs X sign a construction contract. The planning permission is obtained by the building owner, with the help of an architect. But very quickly, difficulties arise.

The work progresses, but the budget soars. Why? Because the quote provided for insufficient works to carry out the construction in accordance with the planning permission. For example, the authorised floor area was larger than that provided for in the quote, or technical elements had been underestimated. Mr and Mrs X then turn against the entrepreneur, accusing him of not having informed them that the quote was insufficient with regard to the planning permission.

The company Deixonne defends itself by asserting that it did not participate in obtaining the planning permission, and that it was not its responsibility to verify compliance. At first instance and on appeal, the judges rule in favour of the entrepreneur. But the Court of Cassation, seised by Mr and Mrs X, quashes the appeal judgment and refers the case back to another court. For the High Court, the entrepreneur failed in his duty to advise: he should have verified the consistency between the quote and the permission, even if he was not at the origin of the latter.

The Reasoning of the Court — Analysed

The Court of Cassation relies on the professional's duty to advise, which derives from Article 1240 of the Civil Code (formerly 1382). That article provides that "any act of a person which causes damage to another obliges the person by whose fault it occurred to repair it". In practice, a professional who commits a fault by not advising his client correctly must compensate the harm suffered.

What does this duty to advise entail in the field of construction? The entrepreneur, as a specialist, must ensure that the project he proposes is feasible and complies with planning rules. He cannot hide behind the fact that the permission was obtained by another (architect or building owner). The Court specifies that "the entrepreneur is bound, by virtue of his duty to advise, to ensure that the estimate is consistent with the construction authorised by the planning permission".

In this case, the court of appeal had held that the entrepreneur was not liable because he had not participated in obtaining the permission. But the Court of Cassation censures this reasoning: even without having participated, the entrepreneur must check the permission and alert the client in case of discrepancy. If the quote is insufficient to carry out the authorised construction, the entrepreneur must point this out before the contract is signed. Failing that, he incurs liability.

This decision confirms well-established case law: the professional is presumed to know the rules of his trade and must enlighten the lay client. It does not create a reversal, but it strengthens the duty to advise in the construction sector, where the financial stakes are often very high.

What This Changes for You — Practically

For owners having a house built, this decision is a protection. If the entrepreneur gives you a quote that is too low compared to the planning permission, he cannot claim an additional payment without having warned you. Concrete example: you obtain permission for a house of 150 m², but the quote only provides for 120 m². If the entrepreneur starts work without alerting you, he will have to bear the cost of the extra 30 m², or you can claim damages.

For landlords renovating a building in Tourcoing, be vigilant: if you entrust an extension to an entrepreneur without checking the permission, and he prepares a non-compliant quote, you could be ordered to demolish the unauthorised works. But you can then turn against the entrepreneur for breach of his duty to advise.

For tenants, even if you are not directly concerned by the permission, you can be affected if your landlord carries out works without authorisation. Check the quotes and permissions before giving your consent.

Finally, for professionals (entrepreneurs, architects), this decision imposes increased vigilance on you. A simple quote can incur your liability for considerable sums. For example, if the actual cost of the works turns out to be 30% higher than the quote due to non-compliance, you will have to compensate the client to the extent of that difference. That is several tens of thousands of euros.

Four Tips to Avoid This Type of Dispute

• Require a planning permission before signing a quote. As an owner, never sign a construction contract without having the permission in hand. Check that the areas, volumes and works of the quote correspond exactly to the permission.
• Have the quote checked by an independent professional. An architect or an engineering firm can compare the quote to the permission and alert you to inconsistencies. This is an investment (around €500 to €1,500) that can avoid much more costly disputes.
• Include a verification clause in the contract. Provide that the entrepreneur undertakes to verify the conformity of the quote to the permission and to notify you of any discrepancy within eight days. In case of failure, he must bear the additional costs.
• Keep all documents. Keep a copy of the permission, the quote, and exchanges with the entrepreneur. In case of dispute, these proofs will be essential. If you are in Wasquehal, do not hesitate to take photos of the site at each stage.

Further Reading: Related Case Law and Developments

This 2002 decision is part of a line of judgments that strengthen the duty to advise of construction professionals. For example, in a judgment of 20 March 2001 (No. 98-22.021), the Court of Cassation had already held that the entrepreneur must inform the building owner of the modifications necessary to comply with planning rules. More recently, the Commercial Chamber, in a judgment of 8 February 2017 (No. 15-16.234), extended this obligation to suppliers of materials: they must verify that the products offered comply with the authorisations.

The trend is therefore towards increased liability of professionals. The courts consider that the lay client cannot be forced to bear the consequences of technical incompetence. In the future, one can expect this obligation to be extended to other actors, such as project managers or inspection bodies.

Checklist Before Acting

• Before signing a quote: Do you have the planning permission in hand? Does the quote mention the number and date of the permission? Do the areas and volumes correspond? If not, ask the entrepreneur to rectify the quote before any signature.
• During the works: Monitor compliance. If the entrepreneur modifies the project without your consent, send a registered letter to contest. You have 5 years from the acceptance of works to take legal action (decennial liability).
• In case of dispute: Gather your evidence (quote, permission, correspondence). Consult a lawyer specialised in property law. Procedural deadlines can range from 6 months to 2 years, depending on complexity. The amounts at stake? Count several thousand euros for an expert appraisal, and potentially tens of thousands in compensation.

Are you in a similar situation? A first 30-minute consultation with Maître Zakine (€45) can save you months of proceedings — and often much more. Book an appointment →