In the drawing area select the roof face.
How to extend wall to roof in revit.
Click modify tab geometry panel join unjoin roof.
Drag the shape handles to extend the roof face.
If necessary use the viewcube to spin the design to facilitate selecting the wall or roof edges.
Shape handles are available for all non horizontal side surfaces.
When you select the roof face roof shape handles display.
In the drawing area select the walls to detach.
When using the pick walls tool there is a setting on the options bar called extend into wall to core.
Click modify walls tab modify wall panel detach top base.
Select an edge of the roof that you want to join and then select the wall or roof to which you want to join the roof.
Select the individual elements from which to detach the walls.
Alternatively if you want to detach the selected walls from all other elements at.
If desired you can specify an offset using a positive or negative value.
On the view control bar for visual style select shaded.
Attach walls to other elements.