This should get you going:
public void CreateRoomAndSeperators() { Document doc = this.ActiveUIDocument.Document; View activeView = doc.ActiveView; //You should make sure you're in a Plan View XYZ pt1 = new XYZ(0, 0, 0); XYZ pt2 = new XYZ(0, 10, 0); XYZ pt3 = new XYZ(10, 10, 0); XYZ pt4 = new XYZ(10, 0, 0); UV pt5 = new UV(5, 5); CurveArray curveArray = new CurveArray(); curveArray.Append(Line.CreateBound(pt1, pt2)); curveArray.Append(Line.CreateBound(pt2, pt3)); curveArray.Append(Line.CreateBound(pt3, pt4)); curveArray.Append(Line.CreateBound(pt4, pt1)); using (Transaction trans = new Transaction(doc)) { trans.Start("Create Room and Boundaries"); ModelCurveArray lines = doc.Create.NewRoomBoundaryLines(activeView.SketchPlane, curveArray, activeView); Room room = doc.Create.NewRoom(activeView.GenLevel, pt5); //now modify the "room" Element's Name, Number, etc. trans.Commit(); } }