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,

GYPSUM BOARD ROOF UNDERLAYMENT SYSTEMS GA27605 PagePARTIAL ROOF UNDERLAYMENT Install 5/in. 15.9 mm type X gypsum board under the combustible roof sheathing on both sides of the party wall for gypsum roof Structural engineering other technical. thank you all for your responces. one more question on

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