Responsibility design
A limiting factor with multi-purpose roofs is often the load-bearing capacity of a roof. In existing construction, the existing structure will often need to be reinforced. A structural engineer can calculate whether it is necessary and what modifications are required. When people also enter the roof, safety is also a major concern. The roof must therefore be given the necessary modifications, such as a sufficiently high parapet. This often requires a design.
It is important to know who is responsible for the design. For example, consider the situation where too little load carrying capacity was calculated. Design responsibility depends on how parties have contracted. In general, three different situations can be distinguished:
- Roofing contractor executes design: In a traditional contracting arrangement, where the client hires a structural engineer and architect to create a design, the roofer only performs the design. In this situation, the client is responsible for the design and any errors in it.
- Roofing contractor creates and executes design: If the roofer not only constructs the roof but also makes the design and calculations, the design responsibility shifts to the roofer.
- Roofing contractor works in construction team: If there is a construction team for the realization of the roof, the client, consultants and contractor are jointly responsible for the correctness of their own designs and recommendations.
Although this distinction seems clear at first glance, in practice it is not always easy to determine who is responsible for the design. A common example is when the roofer creates working drawings based on the client's design. This does not automatically mean that the design responsibility falls to the roofer. The responsibility for the design often remains with the client.
Alert duty
The duty to warn also comes into play, especially when the design comes from the client. Despite having agreed that the design responsibility rests with the client, a roofer may still be liable. Namely, if he violates his duty to warn.
The roofer has a duty to notify the client if obvious errors in the design are discovered. If the roofer fails to warn in writing and as specifically as possible when he should have done so, he may be liable for the resulting damage. Should the design originate from the client and it contains an error, this may be grounds to lay (part of) the damage on the client. After all, in that case it is the client's "own fault". Even if the client is expert and nevertheless failed to notice the error in his design, this may be a reason to lay part of the damage on the client.
Tips for practice
In short, it is important to clarify in advance who is responsible for the design and to document this in the contracting agreement. It is also essential to record in writing any deviations from the design during the execution of the work, including the reasons and initiative for them. Furthermore, careful consideration should be given to the importance of the duty to warn.
