@Wouter The script you are showing will only create Area Boundary Lines for the room boundaries, since you are only collecting rooms. So if you want to also create lines for the wall centerlines, you will also have to collect the walls and obtain their centerlines. A quick forum search brought me to this: Automation of Area Boundary Lines
Also I am wondering what the purpose of the Element.Location node is because the Room Boundaries output node already outputs the curves. Additionally it looks like you are feeding a PolyCurve.ByJoinedCurves node into another PolyCurve.ByJoinedCurves which won’t work.