Add a Roof
Add the roof to the drawing-model pair reserved for the purpose. Use the floor plan to whose walls you wish to bind the roof as the reference drawing. Define the roof parameters and add the roof to approximately the correct location. Bind the roof in place with geometric constraints, see Designing the Roof of a Parametric Building Model.
Do not use eave lines when adding a roof to a parametric building model. If the roof is difficult to add without an eave line, delete the eave line before defining geometric constraints between the roof and the reference drawing walls.
If you are not designing a parametric building model, you can first add an eave line in the floor plan, which you can use when indicating the roof points.