Belgian construction law has traditionally developed through a combination of case law, sector-specific customs and extensive contractual arrangements, rather than through a comprehensive statutory framework. While this approach has allowed for a high degree of contractual flexibility, it has also resulted in an increased importance of negotiation and contractual arrangements, particularly in complex projects involving multiple actors and interfaces. Against this background, Book 7 aims to articulate general principles applicable to construction agreements, situating them within a broader legal framework while introducing specific rules tailored to immovable works.

In January 2026, we hosted a webinar addressing the key innovations proposed under Book 7 with respect to sale, lease and construction agreements relating to immovable property. This article reflects the part of that presentation devoted to construction agreements. This article outlines the key features of the draft legislation dated 20 February 2025, with particular attention to (i) the qualification of construction agreements as a subcategory of service agreements, (ii) the codification of the double acceptance mechanism in the Civil Code, (iii) the conformity defects, and (iv) the proposed regimes governing limitation periods, including the observations raised by the Council of State.

1. Construction agreements as a subcategory of service agreements

Book 7 introduces a general regime for service agreements, defined as contracts under which a service provider, acting without subordination, undertakes to perform a material or intellectual service for a client.

Construction agreements are expressly recognised as a specific subcategory of service agreements. In addition to the general regime on service agreements, Book 7 provides distinct provisions for services relating to immovable works, including in particular:

  • the construction, transformation, or demolition of immovable property or a part thereof; and
  • design or technical services, including architectural and engineering services.

By embedding construction agreements within the broader framework of service agreements, Book 7 promotes conceptual coherence within the Civil Code, while at the same time preserving rules that reflect the technical complexity and economic realities inherent in construction projects.

2. Codification of the double acceptance mechanism

One of the cornerstones of Belgian construction practice – the double acceptance mechanism – is now expressly codified in Book 7. This mechanism is long established in market practice and already reflected in existing legislation (notably the Breyne Act and public procurement law) and consists of:

  • Provisional acceptance (délivrance provisoire / voorlopige oplevering), involving the material and/or intellectual handover of the works (retirement / inontvangstname).
  • Final acceptance (délivrance définitive / definitieve oplevering), corresponding to the acceptance of the works (l’agréation / de aanvaarding), whereby the project owner confirms that the works were duly delivered within the agreed timeframe and are free from any conformity defects that a reasonable project owner could have detected.

Book 7 confirms the suppletive nature of this mechanism: parties remain free to adapt or exclude the double acceptance mechanism contractually. This codification is consistent with established case law, according to which, where a double acceptance mechanism is agreed, final acceptance constitutes the acceptance of the works and the discharge of the contractor for all visible defects.  

Book 7 further provides that, where an architect or another third party is entrusted both with the design of the works and with the control of their execution, acceptance of the works of the contractor also triggers acceptance of the architectural services.

This approach has been questioned by the Council of State, as it departs from general contract law by linking acceptance under one contract to performance under another. If maintained, this rule could affect the professional liability exposure for architects, design offices and other consultants.  

3. Conformity defects

Book 7 introduces a unified concept of conformity defects applicable to all service agreements including construction agreements.

Works are deemed to be in conformity where they comply with the contractual specifications and meet the legitimate expectations of the project owner, having regard to applicable law, customary practice, good faith, the nature of the property, the parties’ expertise and the circumstances of the case.

The contractor is liable for conformity defects that existed at least in germ at the time of material handover (délivrance / levering), provided that a fault can be established.

Book 7 draws a clear distinction between ordinary conformity defects and stability-threatening conformity defects.

Ordinary conformity defects are defects that do not affect, nor threaten, the structural stability of the building and are governed by the general provisions with respect to service agreements.

By contrast, stability-threatening defects concern conformity defects that affect or endanger the structural stability of a building, including defects relating to the soil. The liability with respect to stability-threatening defects  corresponds to the traditional decennial liability regime.

Book 7 confirms that the stability-threatening defects constitute mandatory public order law that applies to all service agreements with respect to immovable goods, irrespectively of any fixed price arrangement; provided that the stability-threatening defect manifests itself at the latest within ten years following acceptance of the works (agréation / aanvaarding).

As a consequence of this public order character, any contractual clause seeking to exclude or limit liability for stability-threatening conformity defects is therefore prohibited and void. Parties may, however, agree to extend or aggravate this liability in favour of the project owner.

4. Limitation periods: clarification tempered by the Council of State’s observations

Book 7 introduces differentiated limitation regimes depending on the nature of the defects. While this structure is intended to enhance legal certainty, it has given rise to concerns, notably in the Council of State’s advice of 28 April 2025.

For ordinary conformity defects, several time limits interact:

  • the contractor remains liable for conformity defects that appear within ten years following acceptance of the works (agréation / aanvaarding);
  • the project owner must notify the defect within a reasonable period after its discovery or after it should reasonably have been discovered and at the earliest upon delivery of the works (délivrance / levering);
  • legal proceedings must be initiated within two years following notification, provided that this period may in any event start no earlier than two years after delivery of the works (délivrance / levering).

In practice, this will at one hand give some legal security to what is meant with initiating legal proceedings within a reasonable time (bref délai / korte termijn) for hidden defects. At the other hand, the combined effect of these rules may allow claims to be brought up to twelve years after acceptance, particularly where defects are discovered at the end of the limitation period.

For stability-threatening conformity defects, a stricter regime applies:

  • liability is limited to defects that appear at the latest within ten years after acceptance of the works;
  • no prior notification requirement applies;
  • legal proceedings must be initiated within the same ten-year period, which serves both as the liability period and the limitation period.

The wording adopted with respect to the duration of liability aligns with the existing case law of the Belgian Court of Cassation and clarifies the scope of the decennial liability period. While acceptance of the works determines the end of the ten-year liability period, it does not constitute its starting point. Stability-threatening conformity defects may therefore give rise to liability even prior to acceptance, in particular where (final) delivery and acceptance have not taken place due to an ongoing dispute between the project owner and the contractor.

In its advice of 28 April 2025, the Council of State made several observations regarding the draft provisions of Book 7, in particular regarding the limitation periods outlined above.

First, the Council of State questioned the coherence of the proposed rules, in particular the choice to make delivery (délivrance / levering), rather than acceptance (agréation / aanvaarding), the starting point of the notification period for ordinary conformity defects. This is particularly problematic in construction practice, where delivery and acceptance often do not coincide and where inspections are carried out in the interim. In such situations, the project owner may be required to notify defects before the acceptance process, which constitutes in principle the decisive stage for assessing conformity, has been completed. The Council of State therefore called on the legislator to clarify and confirm its intention on this point.

Secondly, the Council of State questioned whether the differentiated treatment of ordinary conformity defects and stability-threatening conformity defects is sufficiently justified. In particular, it observed that defects of lesser severity may, in practice, benefit from a longer effective action period than defects threatening the structural stability of the building, raising potential issues in terms of equality and non-discrimination.

These observations confirm that the rules on limitations under Book 7 remain unsettled and that their final scope will depend on how the legislator addresses the Council of State’s remarks.

5. Conclusion: codification as a tool for smoother negotiations

The draft provisions of Book 7 reflect a clear intent to structure Belgian construction law by codifying established principles within a coherent statutory framework. By placing construction agreements under the general regime of service agreements and formalising mechanisms such as double acceptance and decennial liability, the legislator seeks to consolidate existing case law and market practice.

As highlighted by the Council of State, certain aspects of the draft raise practical and interpretative questions that may still evolve during the legislative process.

For practitioners, Book 7 brings greater clarity to the legal framework governing construction agreements, while largely preserving contractual freedom, as most of its provisions remain suppletive.

Careful contractual drafting will therefore continue to play a key role in structuring projects and allocating risk.

For further information or to discuss the impact of Book 7 on your future construction projects or transactions, do not hesitate to contact one of our lawyers below.