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,

Home Butler Manufacturing Producer of metal building systems and architectural products for the nonresidential construction market. Includes an industry glossary and literature, company. Slate Wikipedia, the free encyclopedia Slate roof tiles are usually fixed either with nails, or with hooks as is common with Spanish slate.

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