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Discovering defects while the site is still under construction is a stressful situation, but it is also an opportunity: unlike hidden defects that only appear after handover, you can still act to have the work corrected before it is finished. Here is what to do.
First reaction: don’t let the work continue
As soon as you discover a serious non-conformity (poorly poured foundations, masonry that fails to meet building standards, a defective frame), stop the affected work. Continuing construction on a structure that is already flawed worsens the damage and makes it harder to establish liability. Notify the contractor immediately, in writing.
The joint inspection report: the key piece of evidence
Arrange a joint inspection report: summon the contractor to the site (by registered letter with acknowledgement of receipt) and, whether they attend or their absence is duly recorded, have an official record of the defects drawn up. Calling in a bailiff gives it maximum evidentiary weight. Dated photos, measurements, samples – everything must be documented. This record will form the basis for the formal notice and for any future expert assessment.
Formal notice to redo the work to professional standards
Send a formal notice by registered letter requiring the contractor to redo the non-compliant work within a reasonable timeframe. Reference the contractual documents (quote, plans, applicable DTU standards). If the contractor disputes this, the disagreement centres on compliance with building standards – and this is where technical expertise becomes essential.
Preventive court-supervised expert assessment (Article 145 summary proceedings)
If the disagreement persists, you can ask the summary proceedings judge for a preventive court-supervised expert assessment (Article 145 of the French Code of Civil Procedure). The court expert, independent and sworn in, records the defects, determines whether they comply with building standards, and assesses the remedial work required. Carried out before handover, this assessment permanently secures the evidence and guides the next steps of the project or dispute.
Suspend payments
As long as the defects have not been corrected, suspend payments for the affected work. Payment is the counterpart of compliant work; paying despite a non-conformity weakens your position. Place disputed amounts in escrow if necessary. Conversely, don’t withhold the entire contract if other parts of the work are compliant, or you risk being held liable for termination of the contract.
The role of the independent building expert
An independent building expert gives you an immediate technical assessment: identifying the nature of the defect (workmanship error, non-compliant materials, failure to meet a DTU standard), assessing its severity, and listing remedial solutions. Their report, drawn up as the project progresses, lets you make your case to the contractor and prepare for a possible court-supervised expert assessment. They are your best ally in regaining control of a project that is going off track.
Learn more
- Contractor abandoning the site: the procedure to protect yourself and resume works
- Ten-year structural warranty and dommages-ouvrage (DO) insurance: the compensation mechanism for construction defects
- Earthworks and landslides: common defects on sloped land (Alpes-Maritimes and Var)
📅 Updated on 25/07/2026 – By Cassini Expertise, independent building expert for the Alpes-Maritimes (06) & Var (83). Free quote: 04 22 46 06 04.
Learn more:
Frequently asked questions
What should I do if I find a defect while construction is underway?
Stop the affected work immediately to avoid making things worse. Then have the defects recorded by a bailiff or an expert, and notify the builder or project manager in writing, asking them to correct the faults. Finally, if no amicable solution is found, you can take legal action – but it is essential to respect the statutory deadlines.
How do I document a construction defect on site?
Call in a bailiff to draw up a precise, dated record, or ask a building expert to assess the extent of the defects. Take photos and videos, and keep all documents relating to the works. This record will serve as evidence in the event of a dispute.
What recourse do I have for defects that occur during construction?
You can first send a formal notice to the contractor requiring them to correct the defects within a reasonable time. If nothing is done, you can bring the matter before the courts – but be mindful of the statutory warranties: the one-year completion warranty, the two-year biennial warranty on equipment, and the ten-year structural warranty, depending on the nature of the defects.
Survey carried out by Frédéric Faucouneau, independent building expert – Antibes, Alpes-Maritimes (06), Var (83), Bouches-du-Rhône (13). Find out more
📅 Last updated 02/11/2026 - Cassini Expertise, independent building expert – departments 06, 83 and 13.