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,

GAF to Relocate Corporate Headquarters to Parsippany WAYNE, NJ 11/19/13 — GAF, North America’s largest roofing manufacturer, plans to relocate its corporate headquarters to Parsippany, N.J. once renovations are. Building Materials Corporation of America, Inc. Private. Building Materials Corporation of America, Inc., doing business as GAF

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