Belgian law protects buyers against hidden defects (vices cachés): serious flaws that existed before the sale, were not visible on inspection, and make the property unfit for use. A private seller can limit liability with an “as is” clause if acting in good faith, but a professional seller cannot escape it. Act quickly if one appears.
A hidden defect (vice caché) is a specific legal idea, not any fault you happen to find later. To qualify, a defect must be serious enough to make the property unfit for its intended use or seriously reduce it, must have existed before the sale, and must have been hidden, meaning not detectable by a reasonably attentive buyer on a normal inspection. A crack you could have seen, or a fault disclosed before the sale, does not count.
The seller’s position depends heavily on who they are, which is the distinction that matters most. A private seller (a natural person selling their own home) usually inserts an “as is” clause in the compromis excluding liability for hidden defects, and Belgian law allows this provided the seller acted in good faith, meaning they were genuinely unaware of the defect. If the private seller knew and concealed it, that clause does not shield them. A professional seller (for example a developer or a company selling in the course of business) is treated as knowing the defects of what they sell and cannot validly exclude this liability. Source: Belgian Civil Code on hidden defects.
The counter-intuitive lesson is that timing can decide the case: the law expects a buyer to act within a short period after discovering the defect, so a slow reaction can weaken an otherwise valid claim. This is also why the pre-purchase checks matter, since a defect that was visible or disclosed is not “hidden” at all.
If you suspect a hidden defect, gather evidence, note the date of discovery, and take legal advice quickly; the compromis wording and the seller’s status will frame your options.
At a glance
| Aspect | Private seller | Professional seller |
|---|---|---|
| “As is” clause allowed? | Yes, if in good faith | No, cannot exclude liability |
| Assumed to know defects? | No (unless proven) | Yes, treated as knowing |
| Defect must be | Serious, prior, and hidden | Serious, prior, and hidden |
| Buyer must act | Quickly after discovery | Quickly after discovery |
| Clause fails if | Seller knew and concealed | N/A, liability stands |