Contractor liability
Investigation and warning obligation (NL)

Every contractor has certain obligations. These rules apply in The Netherlands.

Every contractor is by definition obliged to warn the client in a timely manner of inaccuracies in the assignment that he knows or should be aware of, and of defects or unsuitability of items originating from the client, including the surface for the work, also insofar as he knows or should know.

In other words, the contractor must recognise the risks that threaten the delivery of proper work. This also applies when the client himself is an expert (if only because people can make mistakes or overlook things). This rule is laid down in Article 7:754 of the Dutch Civil Code.

It is incorrect that if the contractor has violated his obligation to investigate and warn, there is no room for an appeal to the client's own fault. After all, Article 6:101 of the Dutch Civil Code provides for the possibility that both a third party and the injured party themselves have contributed to the damage. 'Client's own fault' can, for example, arise from failure to take damage-reducing measures.

This means that any “unknowing” customer who suspects damage due to “rising damp” requests a contractor to carry out injection works, each contractor is obliged to carry out the necessary preliminary investigations. If it turns out that if a contractor does the necessary preliminary investigations, he must always find a third cause. If it turns out that the house dries up completely after removing the identified third causes, without injecting, any contractor who injects walls is making a serious mistake by not carrying out necessary preliminary investigations or not carrying out them sufficiently.

This also means that no contractor can install interior insulation without serious measurable or visible consequential damage. If there is also a mold explosion behind the false wall, the contractor has indirectly caused very serious health damage by not carrying out sufficient preliminary investigations and not sufficiently informing the customer.

This also means that a cavity wall insulation contractor cannot insulate any cavity wall without hydrophobicising the walls or at least painting them or providing them with another waterproof finish. After all, the rainwater will run into the insulation material and even cause a negative lambda value with even more energy loss.