What rules of good practice cover
Rules of good practice denote the body of technical practices a normally competent and diligent professional is expected to know and apply. They are assessed at the time the work is carried out.
They have no official list but draw on several sources. Standards are the most accessible of them.
Belgian standards, approved or registered, which are legally regarded as rules of good practice.
Industry technical publications, information notes and guides, widely followed in practice without holding the status of standards.
Established professional practices, including unwritten ones, where generally accepted.
Manufacturers' instructions, whose disregard is regularly treated as fault.
It is an evolving body, not a fixed framework. What complied with good practice twenty years ago may no longer do so, and assessment is made at the time of execution.
Why standards form part of them
This is the link that gives everything else its meaning. Compliance with a standard supports the proof of diligence.
Belgian standards enjoy a presumption of technical quality. Having followed them creates a presumption that the work complies with good practice.
Departing from them requires technical justification, on the basis of tests or other agreed evidence. The alternative solution is not prohibited; it must be demonstrated.
That mechanism is developed in the article on when a standard becomes binding. The two routes are compared there.
Ten-year liability
The heaviest regime in Belgian construction law, and the one that makes rules of good practice operative. It concerns ten-year liability.
The principle. Architects and contractors answer for ten years for defects of construction, including defects of the ground, affecting the soundness or stability of the works.
The starting point is acceptance of the works.
The regime is of public policy. It can be neither excluded nor limited by contract, and the Court of Cassation has held that a clause limiting the architect's liability to their share of the damage was, to that extent, contrary to public policy.
The period is one of forfeiture, which can be neither suspended nor interrupted, save by proceedings on the merits or express acknowledgment of liability. An action merely seeking appointment of an expert does not interrupt it.
What ten-year liability covers and excludes
The distinction is decisive and often misunderstood. Compliance is not an automatic exoneration.
| Within ten-year liability | Outside it |
|---|---|
| structural works of immovable construction | finishing works |
| substantial immovable works | maintenance or decoration works |
| defects affecting soundness or stability | very localised repairs |
Minor latent defects fall outside ten-year liability. These are defects that do not compromise soundness and that could not be discovered on careful and thorough examination by a normally prudent person in the same situation.
But they do not escape all liability. The majority case law holds that contractor and architect remain liable for them after acceptance, on a contractual basis. Unlike ten-year liability, that regime can be adjusted by contract.
The burden of proof
A technical point with important practical consequences. It concerns the burden of proof.
Ten-year liability is not an automatic guarantee but a fault-based liability. The client must in principle prove a construction defect attributable to the architect or contractor.
A notable exception applies to defects of ground and materials, where it is accepted that architect and contractor owe an obligation of result, with a presumption of fault where damage occurs.
It is precisely here that compliance with standards plays its role: it is the simplest evidence to produce in showing that the work complied with good practice. The documented reference supports the defence.
Compulsory insurance
Since the Act of 31 May 2017, contractors and architects must insure their ten-year liability for works relating to housing. The certificate of insurance is checked before the works begin.
Two clarifications.
The obligation covers ten-year liability alone, that is soundness and stability, and weathertightness where it endangers stability. It does not cover the whole range of professional liabilities.
Absence of insurance does not exonerate. An uninsured professional remains liable, from their own resources.
What this means for a professional
Four rules.
Following standards, even voluntary ones, is the least costly protection. It converts an uncertain technical discussion into a favourable presumption.
Document departures. A non-standardised solution should be accompanied by its technical justification at the moment it is decided, not ten years later.
Do not rely on a limitation clause for ten-year liability. It will be set aside.
Distinguish the regimes. A weathertightness defect engages ten-year liability only if it endangers soundness, which the courts assess strictly.
This article reflects rules and case law at the date of checking and serves professional orientation. It does not constitute legal advice and does not replace assessment of the individual case.