The main factor that may weaken the stability of the roof structure is dampness. On its negative impact it is particularly exposed rafter framing, which deform under impact of water. Therefore is important roof protection against getting in  water into its internal structure.

Typically, investors during the construction of the roof attach great importance both for building materials, as well as careful execution. Unfortunately, later very often they forget about the survey, and any minor defects  commission outsource cheaper and often non-professional roofing companies. This is a big mistake,

Chrysler sued over defective leaking sunroofs Got a. I have ajeep liberty I bought from carmax inmy sun roof leaks also my roof is now stained yes we could blame the but if they would of put a better gasket on. Blog The Roof Cleaning Institute

A very important element that must be considered when the roof is projected, is ventilation, allowing drainage of excess dampness from under the roofing.