Construction and Mandate Contracts in Swiss Building Law
Real estate construction in Switzerland rests on two fundamental contractual pillars: the construction services contract and the mandate contract. These legal instruments determine the relationships between project owners, contractors, architects and engineers throughout construction projects. Swiss law draws a clear distinction between these two types of contracts, governed respectively by arts. 363 to 379 CO for the construction services contract and arts. 394 to 406 CO for the mandate. This distinction is fundamental as it determines the responsibilities, obligations and rights of all parties involved in any construction project. PBM Avocats assists stakeholders in the sector in negotiating, drafting and performing these contracts in Geneva and Lausanne.
Key Differences Between Construction Services Contract and Mandate
| Criterion | Construction Services Contract (art. 363 CO) | Mandate (art. 394 CO) |
|---|---|---|
| Nature of obligation | Obligation of result (compliant work) | Best efforts obligation (diligence) |
| Typical party | General contractor, subcontractor | Architect, engineer, project manager |
| Defect warranty | Yes — specific legal warranty (arts. 367-371 CO) | No specific warranty — contractual liability |
| Price | Lump sum or cost-plus | Fee (time-based or fixed) |
| Termination | Client right at any time with compensation (art. 377 CO) | Free revocability (art. 404 CO) |
The Architect's Mandate in Construction
The architect occupies a central role in the construction chain. Their relationship with the project owner is generally governed by a mandate contract. The architect's obligations include:
- Design phase: drafting of plans, permit application, technical studies
- Planning phase: coordination of specialist engineers, calls for tender
- Supervision phase: site supervision, coordination between contractors, compliance with plans
- Settlement phase: verification of invoices, final accounts
The architect's liability is a best efforts obligation: they must act with the care of a reasonably diligent professional. A professional liability insurance is essential and is generally required for registered architects.
The General Contractor's Contract
The general contractor takes on overall responsibility for the construction and coordinates all subcontractors. The general contract is a construction services contract where the result obligation is central: the general contractor guarantees delivery of a compliant building at the agreed price and time. They are responsible for the work of their subcontractors as if it were their own.
The SIA Norms (Société Suisse des Ingénieurs et des Architectes)
In practice, many construction contracts in Switzerland refer to SIA norms, particularly:
- SIA 118: general conditions for construction works
- SIA 102: service and fee regulations for architects
- SIA 103: service and fee regulations for civil engineers
These norms, while not legally binding, are frequently contractually incorporated and represent the standard practice of the profession. PBM Avocats has expertise in interpreting and applying these norms in disputes.