A person that specializes in roof construction is called a roofer.
A more recent design is the installation of a roof deck with foil-backed foam along with a second deck that is air-gapped away from the foil-backed foam to allow air to flow vertically to a ventilation outlet at the peak of the roof—it is a double deck design with an air gap. This design improves efficiency.
The durability of a roof is a matter of concern because the roof is often the least accessible part of a building for purposes of repair and renewal, while its damage or destruction can have serious effects.
When the warm, moist air from below rises into the cold roof space; condensation begins as the air temperature drops to the 'dew point' or as the warm air comes into contact with any of the cold surfaces in the roof.