Hello Eric,
 
	 
 
	thanks for your advice, I activated my signature:-)
 
	 
 
	I read this post
 
	 
 
	 
 
	But I don't think that this solution fit my needs, because of the additional attic/room walls.
 
	When I make a room and raise the ceiling, I have room walls inside the second floor, that I don't want.
 
	What I need is an empty second floor with a "dormer" without any walls inside.