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The professional skills

For many activities in the construction sector, the contractor must have a specific professional qualification. The following activities require proof of sectoral professional competence:

  • Structural work

  • Plastering, cementing and screed work

  • Installation of tile, marble and natural stone

  • Roofing and waterproofing works

  • Joiner or glazier

  • General joinery

  • Final finish

  • Central heating, climate control, gas and plumbing

  • Electrical engineering activities

  • General contractor

  • Installer-frigorist

You can check in the registers of the Crossroads Bank for Enterprises whether the contractor has a certificate of professional competence for certain works.

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It is recommended to work only with contractors who have the required professional qualifications. A lack of evidence of appropriate professional competence may be an indication that the contractor is not competent enough to carry out the work in question.

If you have nevertheless engaged with a contractor who does not have the required professional qualifications, the contract with regard to these non-qualified activities may be wholly or partially declared null and void. This invalidity means that the agreement is deemed never to have existed: one thus returns to the situation before an agreement ever existed.

In principle, this means that the contractor must return the funds received to you as the client and he must be given possession of his materials and work carried out again. In concrete terms, it is often not possible to revindicate these as they are incorporated in a building. The nullity is therefore particularly detrimental to the contractor.

The court  could then “go back”   to the state before any agreement was ever made. In other words, the contractor ran the risk of having to return all monies he had received from the client. However, there were judges who lent, and  then awarded fair compensation on the basis of  "enrichment without cause" of the customer._cc781905-5cde-3194-bb3b-1586bad5c This always happened without allocating any “profit” for the contractor.

Attention! Since January 1, 2019, this arrangement whereby you can claim the annulment of the agreement on this ground has been abandoned in the Flemish region. Since 1 January 2019, this obligation has been dropped under pressure from Europe. Strictly speaking, possession of the certificate of professional competence is therefore no longer required.

However, this does not mean safe-conduct for construction contracts concluded before 1 January 2019. For those contracts, the prevailing view is that the nullity sanction can still be invoked.


However, according to the most followed view in legal doctrine, the moment of the conclusion of the agreement is decisive. This means that a building contract concluded before 1 January 2019, if the contractor does not have the required professional competence, could still be declared null and void. If the agreement has been concluded at a later date, this defense against the contractor can no longer lead to nullity.

It therefore remains  therefore important for building contracts concluded before 1 January 2019 to  to have the correct professional skills for the works you carry out or have carried out by a subcontractor.

Article: Construction lawyer

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