Abstract: A protective peripheral cornice of a building which cornice is an equal angle broad flanged beam inserted between the top of the wall and the end section of the ceiling. Such beam is made of light material which is totally enveloped in a metal sheet except for two interruptions in each of which the sheet is replaced by bridgelike means of insulating plastic material which extend for about 1/2 the panel thickness; one of said interruptions being located across the horizontal median plane of the roof panel while the other is located across the vertical median plane of the wall panel. Such interruptions having thus the function of thermal insulations or thermal barriers.