Warranties are used as evidence of a primary contract under which an agreement must be concluded with a third party outside the primary contract. Sometimes an architect, contractor or subcontractor must guarantee to a lessor, tenant or buyer that he has fulfilled his obligations under a construction contract. With regard to best practices, it would be preferable, from a commercial point of view, to specify in the tender dossier before the contract that guarantees are necessary as a condition of the contract or subcontract, and to submit a draft form of guarantee so that the requirements are known from the outset.