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,

Pros and Cons of popular roofing materials Composition shingles, wood shakes, clay roof tile, concrete roof tile, slate roofing, metal roofs, hot mop, failing roofs, fire protection, pros and cons Domestic roof construction Wikipedia, the free encyclopedia Domestic roof construction is the framing and roof covering

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