Such a

However, this is not enough, since it is necessary that under the roof there is not only heat, but also dry. And for this you need to take care of laying waterproofing — it is laid on rafter beams. Then the roof is sheathed with heat -insulating material (most often mineral wool), and also closed with vapor barrier film. Why do you need such a «pie»? In order to protect the attic from street moisture and dust blown by the wind. In addition, this warns the formation of condensate.