How do we guarantee the watertightness of your roof for 10 years?

Whether or not your roof is guaranteed watertight for ten years depends on a number of factors:

If the roof is in good condition, i.e. recent, with a roof covering in sufficiently good condition and an under-roof, we can guarantee watertightness. In this case, the initial condition of the roof is essential.
If the roof is in poor condition at the base, we cannot guarantee that it will be watertight. That's why we ask that the roof be sufficiently recent.
An old roof in very good condition can also be considered, but we also check whether the roof is insulated. Before installing solar panels, we recommend prioritizing insulation work. Although insulation isn't always mandatory for all structures (e.g., a barn), it's best to follow a logical order in the work.
We emphasize the importance of insulation before installing solar panels. If the roof is not insulated and watertight before the panels are installed, we cannot guarantee watertightness. It makes more sense to carry out the work in sequence, to avoid expense and potential delays. Installing solar panels and having to dismantle them in a few years' time to insulate them is a waste of time and money. In short, we guarantee waterproofing if the roof is in good condition, sufficiently recent, and if there is a good under-roof.