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,

Cool Roofs Department of Energy If you live in a hot climate, a cool roof can Save you money on air conditioning; Make your home more comfortable in hot weather < Average Labour Cost/Price to Repair/Replace a Flat Roof Cost/Price For a Flat Roof/Asphalt/Torch On Felt

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