As you know, there are input and interior doors, and their functions are slightly different. The entrance doors must reliably protect the whole house, so for their manufacture they always choose strong material. For a long time they were made from the best wood species, and for greater reliability they were broken by iron. Currently, the entrance doors are made completely, from metal, since it is much more reliable from all sides. In addition to breaking them much more difficult, such doors are good fire protection, not letting the fire inside the room.
