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,

TLock Shingles Roofing Material and Products. I have heard there are only three manufacturers of TLock in the US and they have a patent on the product and they won t sell to distributors or individual companies. Flat lock roof & wall panels. Copper, Steel, Aluminum

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